Diagram sections — 16 (85 total)
COMPUTER DATA LINES CRUISE CONTROL ENGINE PERFORMANCE GROUND DISTRIBUTION HEADLIGHTS HORN INSTRUMENT CLUSTER INTERIOR LIGHTS POWER DISTRIBUTION POWER DOOR LOCKS POWER WINDOWS SHIFT INTERLOCKS STARTING/CHARGING TRANSMISSION WARNING SYSTEMS WIPER/WASHER
COMPUTER DATA LINES
4.3L 4.3L (VIN Z), Data Link Connector Wiring Diagram, Commercial Chassis with A/T for GMC Forward Control P1994 3500 List of elements for 4.3L (VIN Z), Data Link Connector Wiring Diagram, Commercial Chassis with A/T for GMC Forward Control P1994 3500: 10 (4.3l) (5.7l & 7.4l) (behind left side of shipping panel) (front of engine) A14 diagnostic test c250 C201 Data link connector F9 serial data c251 G125 Powertrain control module (behind left side of shipping panel) 4.3L (VIN Z), Data Link Connector Wiring Diagram, Commercial Chassis with M/T for GMC Forward Control P1994 3500 List of elements for 4.3L (VIN Z), Data Link Connector Wiring Diagram, Commercial Chassis with M/T for GMC Forward Control P1994 3500: 8 (behind left side of shipping panel) (front of engine) A8 serial data A9 diagnostic test c251 C201 Data link connector G125 Powertrain control module (behind left side of shipping panel) 4.3L (VIN Z), Data Link Connector Wiring Diagram, Cutaway for GMC Forward Control P1994 3500 List of elements for 4.3L (VIN Z), Data Link Connector Wiring Diagram, Cutaway for GMC Forward Control P1994 3500: 8 (behind left side of i/p, below steering column) (top right front of engine) A14 diagnostic test c303 C224 Data link connector F9 serial data c304 G119 Powertrain control module (mounted under driver's seat)
5.7L 5.7L (VIN K), Data Link Connector Wiring Diagram, Commercial Chassis with A/T for GMC Forward Control P1994 3500 List of elements for 5.7L (VIN K), Data Link Connector Wiring Diagram, Commercial Chassis with A/T for GMC Forward Control P1994 3500: 10 (4.3l) (5.7l & 7.4l) (behind left side of shipping panel) (front of engine) A14 diagnostic test c250 C201 Data link connector F9 serial data c251 G125 Powertrain control module (behind left side of shipping panel) 5.7L (VIN K), Data Link Connector Wiring Diagram, Commercial Chassis with M/T for GMC Forward Control P1994 3500 List of elements for 5.7L (VIN K), Data Link Connector Wiring Diagram, Commercial Chassis with M/T for GMC Forward Control P1994 3500: 8 (behind left side of shipping panel) (front of engine) A8 serial data A9 diagnostic test c251 C201 Data link connector G125 Powertrain control module (behind left side of shipping panel) 5.7L (VIN K), Data Link Connector Wiring Diagram, Cutaway for GMC Forward Control P1994 3500 List of elements for 5.7L (VIN K), Data Link Connector Wiring Diagram, Cutaway for GMC Forward Control P1994 3500: 8 (behind left side of i/p, below steering column) (top right front of engine) A14 diagnostic test c303 C224 Data link connector F9 serial data c304 G119 Powertrain control module (mounted under driver's seat)
6.5L 6.5L (VIN F), Data Link Connector Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500 List of elements for 6.5L (VIN F), Data Link Connector Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500: 8 (behind left side of shipping panel) (top center front of engine) A8 diagnostic test c253 B10 serial data C201 Data link connector G125 Transmission control module (behind left side of shipping panel) 6.5L (VIN Y), Data Link Connector Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500 List of elements for 6.5L (VIN Y), Data Link Connector Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500: 8 (behind left side of shipping panel) (top center front of engine) A8 diagnostic test c253 B10 serial data C201 Data link connector G125 Transmission control module (behind left side of shipping panel)
7.4L 7.4L (VIN N), Data Link Connector Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500 List of elements for 7.4L (VIN N), Data Link Connector Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500: 10 (4.3l) (5.7l & 7.4l) (behind left side of shipping panel) (front of engine) A14 diagnostic test c250 C201 Data link connector F9 serial data c251 G125 Powertrain control module (behind left side of shipping panel) 7.4L (VIN N), Data Link Connector Wiring Diagram, Cutaway for GMC Forward Control P1994 3500 List of elements for 7.4L (VIN N), Data Link Connector Wiring Diagram, Cutaway for GMC Forward Control P1994 3500: 8 (behind left side of i/p, below steering column) (top right front of engine) A14 diagnostic test c303 C224 Data link connector F9 serial data c304 G119 Powertrain control module (mounted under driver's seat) 7.4L (VIN N), Data Link Connector Wiring Diagram, Motorhome Chassis for GMC Forward Control P1994 3500 List of elements for 7.4L (VIN N), Data Link Connector Wiring Diagram, Motorhome Chassis for GMC Forward Control P1994 3500: 8 (inside center of shipping panel) (top right front of engine) A14 diagnostic test c250 C204 Data link connector F9 serial data c251 G125 Powertrain control module (inside left side of shipping panel)
CRUISE CONTROL Cruise Control Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500 List of elements for Cruise Control Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500: 19 Brk sw input C r/a input Cruise control activator Cruise control brake switch (on brake pedal support) Cruise control module (behind left side of shipping panel) Fuse block G202 (at bus bar ground) Gages fuse 20a Ground Hot in run or start Ign Nca On/ off On/off input R/a S/c S/c input Vehicle speed sensor buffer (left side of shipping panel) Vss input Cruise Control Wiring Diagram, Motor Home Chassis for GMC Forward Control P1994 3500 List of elements for Cruise Control Wiring Diagram, Motor Home Chassis for GMC Forward Control P1994 3500: 19 Alt fuse 20a Brk sw input Cruise control activator Cruise control brake switch (on brake pedal support) Cruise control module (behind left side of shipping panel) Fuse block G114 (left rear of engine) Ground Hot in run or start Ign On/ off On/off input R/a R/a input S/c S/c input Tan Vehicle speed sensor buffer (left side of shipping panel) Vss input
ENGINE PERFORMANCE
4.3L 4.3L (VIN Z), Engine Performance Wiring Diagrams, A/T Commercial Chassis (2 of 3) for GMC Forward Control P1994 3500 List of elements for 4.3L (VIN Z), Engine Performance Wiring Diagrams, A/T Commercial Chassis (2 of 3) for GMC Forward Control P1994 3500: 33 (center rear 4.3l and 7.4l 5.7l Accy Alt fuse 20a Bulb test Distributor Engine coolant temperature sensor (top front of engine) Fuse block G125 (at generator bracket) Hot at all times Hot in run, bulb test, or start Ignition coil (top right rear of engine) Ignition switch Instrument cluster Knock sensor (left rear of engine, near oil pressure sender) Knock sensor module (top right side of engine) Lock Malfunction (service engine soon) indicator Manifold absolute pressure sensor (above valve cover) Nca Of engine) Off Pnk Pnk b Pnk/ Provisions for tachometer Red Run Start Tcc/brake switch (on brake pedal support bracket) Throttle position sensor (on throttle body) Trans fuse 10a 4.3L (VIN Z), Engine Performance Wiring Diagrams, A/T Commercial Chassis (3 of 3) for GMC Forward Control P1994 3500 List of elements for 4.3L (VIN Z), Engine Performance Wiring Diagrams, A/T Commercial Chassis (3 of 3) for GMC Forward Control P1994 3500: 28 1-2 shift soleniod 2-3 shift soleniod 4.3l 5.7l and 7.4l Bh conn pin h2 Data link connector (behind left side of shipping panel) Ecm-bat fuse 10a Electronic 4-speed automatic overdrive transmission Fuel pump and sender (in fuel tank) Fuel pump oil pressure switch (top rear of engine) Fuel pump prime connector (no location available) Fuel pump relay (lower left side of shipping panel) Fuse block G125 (at generator bracket) G125 (front of engine near thermostat) G402 (left frame rail near fuel tank) Heated oxygen sensor (in exhaust manifold) Hot at all times Nca Oxygen sensor (in exhaust manifold) Pnk Pressure control solenoid Range mode selector Red Torque converter clutch solenoid Trans- mission temp sensor Vehicle speed sensor (left rear of transmission) Vehicle speed sensor buffer (behind right side of i/p) 4.3L (VIN Z), Engine Performance Wiring Diagrams, M/T Commercial Chassis (1 of 2) for GMC Forward Control P1994 3500 List of elements for 4.3L (VIN Z), Engine Performance Wiring Diagrams, M/T Commercial Chassis (1 of 2) for GMC Forward Control P1994 3500: 73 5 volt ref A/c signal A10 A11 A12 Air conditioning system B10 B11 B12 Battery feed C10 C11 C12 C13 C14 C15 C16 C250 C251 Crank signal Crnk fuse 10a D10 D11 D12 D13 D14 D15 D16 Data link connector (behind left side of shipping panel) Diagnostic test terminal Ecm bat fuse 10a Ecm-crnk fuse 10a Ect signal Egr control Engine coolant temperature sensor (top front of engine) Fuel pump relay Fuel pump signal Fuse block G125 (front of engine) Hot at all times Hot in run, bulb test, or start Hot in start Iac a high Iac a low Iac b high Iac b low Ic bypass Ic control Ic reference high Ic reference low Idle air control actuator (top rear of engine) Ign ecm fused Inj fuse 7.5a Injector 1 control Injector 2 control Knock signal Malfunction indicator lamp Manifold absolute pressure sensor (top rear of engine) Map sensor ground Map signal Oxygen sensor ground Oxygen sensor signal Powertrain control module (left side of shipping panel) Red Sensor ground Serial data System ground Tan Throttle body fuel injector #1 (top of throttle body unit) Throttle body fuel injector #2 (top of throttle body unit) Throttle position sensor (top right side of engine) Tp signal Vss signal 4.3L (VIN Z), Engine Performance Wiring Diagrams, M/T Commercial Chassis (2 of 2) for GMC Forward Control P1994 3500 List of elements for 4.3L (VIN Z), Engine Performance Wiring Diagrams, M/T Commercial Chassis (2 of 2) for GMC Forward Control P1994 3500: 42 (top rear 4.3l 5.7l Accy Alt fuse 20a Bulb test Distributor Egr electronic vacuum regulator solenoid valve (top right front of engine) Egr solenoid (top right side of engine) For tachometer Fuel pump and sender (in fuel tank) Fuel pump oil pressure switch (top rear of engine) Fuel pump prime connector Fuel pump relay (lower left side of shipping panel) Fuse block G125 (at generator bracket) G125 (front of engine G125 (front of engine) G402 (along left frame rail near fuel tank) G402 (left frame rail near fuel tank) Heated oxygen sensor (in exhaust manifold) Hot at all times Hot in run, bulb test, or start Ignition coil (top of engine near distributor) Ignition switch Instrument cluster Knock sensor (right side of engine) Knock sensor module (top right side of engine) Lock Malfunction (service engine soon) indicator Nca Of engine) Off Oxygen sensor (in exhaust manifold) Pnk Pnk b Provisions Red Run Start Vehicle speed sensor (left rear of transmission) Vehicle speed sensor buffer (behind right side of i/p)
5.7L 5.7L (VIN K), Engine Performance Wiring Diagrams, A/T Commercial Chassis and Motorhome (2 of 3) for GMC Forward Control P1994 3500 List of elements for 5.7L (VIN K), Engine Performance Wiring Diagrams, A/T Commercial Chassis and Motorhome (2 of 3) for GMC Forward Control P1994 3500: 33 (center rear 4.3l and 7.4l 5.7l Accy Alt fuse 20a Bulb test Distributor Engine coolant temperature sensor (top front of engine) Fuse block G125 (at generator bracket) Hot at all times Hot in run, bulb test, or start Ignition coil (top right rear of engine) Ignition switch Instrument cluster Knock sensor (left rear of engine, near oil pressure sender) Knock sensor module (top right side of engine) Lock Malfunction (service engine soon) indicator Manifold absolute pressure sensor (above valve cover) Nca Of engine) Off Pnk Pnk b Pnk/ Provisions for tachometer Red Run Start Tcc/brake switch (on brake pedal support bracket) Throttle position sensor (on throttle body) Trans fuse 10a 5.7L (VIN K), Engine Performance Wiring Diagrams, A/T Commercial Chassis and Motorhome (3 of 3) for GMC Forward Control P1994 3500 List of elements for 5.7L (VIN K), Engine Performance Wiring Diagrams, A/T Commercial Chassis and Motorhome (3 of 3) for GMC Forward Control P1994 3500: 28 1-2 shift soleniod 2-3 shift soleniod 4.3l 5.7l and 7.4l Bh conn pin h2 Data link connector (behind left side of shipping panel) Ecm-bat fuse 10a Electronic 4-speed automatic overdrive transmission Fuel pump and sender (in fuel tank) Fuel pump oil pressure switch (top rear of engine) Fuel pump prime connector (no location available) Fuel pump relay (lower left side of shipping panel) Fuse block G125 (at generator bracket) G125 (front of engine near thermostat) G402 (left frame rail near fuel tank) Heated oxygen sensor (in exhaust manifold) Hot at all times Nca Oxygen sensor (in exhaust manifold) Pnk Pressure control solenoid Range mode selector Red Torque converter clutch solenoid Trans- mission temp sensor Vehicle speed sensor (left rear of transmission) Vehicle speed sensor buffer (behind right side of i/p) 5.7L (VIN K), Engine Performance Wiring Diagrams, A/T P/G Cutaway (2 of 3) for GMC Forward Control P1994 3500 List of elements for 5.7L (VIN K), Engine Performance Wiring Diagrams, A/T P/G Cutaway (2 of 3) for GMC Forward Control P1994 3500: 29 (center rear Accy Bulb test Distributor Engine coolant temperature sensor (top front of engine) Fuse block Gages fuse 20a Hot at all times Hot in run, bulb test, or start Ignition coil (top right rear of engine) Ignition switch Instrument cluster Knock sensor (left rear of engine, near oil pressure sender) Lock Malfunction (service engine soon) indicator Manifold absolute pressure sensor (above valve cover) Nca Of engine) Off Pnk Pnk b Pnk/ Provisions for tachometer Red Run Start Tcc/brake switch (on brake pedal support bracket) Throttle position sensor (on throttle body) Trans fuse 10a 5.7L (VIN K), Engine Performance Wiring Diagrams, A/T P/G Cutaway (3 of 3) for GMC Forward Control P1994 3500 List of elements for 5.7L (VIN K), Engine Performance Wiring Diagrams, A/T P/G Cutaway (3 of 3) for GMC Forward Control P1994 3500: 24 1-2 shift soleniod 2-3 shift soleniod Bh conn pin h2 Data link connector (behind left side of shipping panel) Electronic 4-speed automatic overdrive transmission Fuel pump and sender (in fuel tank) Fuel pump fuse 20a Fuel pump oil pressure switch (top rear of engine) Fuel pump prime connector (top of cowl) Fuel pump relay (lower left side of shipping panel) Fuse block G125 (at generator bracket) G125 (front of engine near thermostat) G402 (left frame rail near fuel tank) Hot at all times Nca Pnk Pressure control solenoid Range mode selector Red Torque converter clutch solenoid Trans- mission temp sensor Vehicle speed sensor (left rear of transmission) Vehicle speed sensor buffer (behind right side of i/p) 5.7L (VIN K), Engine Performance Wiring Diagrams, M/T Commercial Chassis (1 of 2) for GMC Forward Control P1994 3500 List of elements for 5.7L (VIN K), Engine Performance Wiring Diagrams, M/T Commercial Chassis (1 of 2) for GMC Forward Control P1994 3500: 73 5 volt ref A/c signal A10 A11 A12 Air conditioning system B10 B11 B12 Battery feed C10 C11 C12 C13 C14 C15 C16 C250 C251 Crank signal Crnk fuse 10a D10 D11 D12 D13 D14 D15 D16 Data link connector (behind left side of shipping panel) Diagnostic test terminal Ecm bat fuse 10a Ecm-crnk fuse 10a Ect signal Egr control Engine coolant temperature sensor (top front of engine) Fuel pump relay Fuel pump signal Fuse block G125 (front of engine) Hot at all times Hot in run, bulb test, or start Hot in start Iac a high Iac a low Iac b high Iac b low Ic bypass Ic control Ic reference high Ic reference low Idle air control actuator (top rear of engine) Ign ecm fused Inj fuse 7.5a Injector 1 control Injector 2 control Knock signal Malfunction indicator lamp Manifold absolute pressure sensor (top rear of engine) Map sensor ground Map signal Oxygen sensor ground Oxygen sensor signal Powertrain control module (left side of shipping panel) Red Sensor ground Serial data System ground Tan Throttle body fuel injector #1 (top of throttle body unit) Throttle body fuel injector #2 (top of throttle body unit) Throttle position sensor (top right side of engine) Tp signal Vss signal 5.7L (VIN K), Engine Performance Wiring Diagrams, M/T Commercial Chassis (2 of 2) for GMC Forward Control P1994 3500 List of elements for 5.7L (VIN K), Engine Performance Wiring Diagrams, M/T Commercial Chassis (2 of 2) for GMC Forward Control P1994 3500: 42 (top rear 4.3l 5.7l Accy Alt fuse 20a Bulb test Distributor Egr electronic vacuum regulator solenoid valve (top right front of engine) Egr solenoid (top right side of engine) For tachometer Fuel pump and sender (in fuel tank) Fuel pump oil pressure switch (top rear of engine) Fuel pump prime connector Fuel pump relay (lower left side of shipping panel) Fuse block G125 (at generator bracket) G125 (front of engine G125 (front of engine) G402 (along left frame rail near fuel tank) G402 (left frame rail near fuel tank) Heated oxygen sensor (in exhaust manifold) Hot at all times Hot in run, bulb test, or start Ignition coil (top of engine near distributor) Ignition switch Instrument cluster Knock sensor (right side of engine) Knock sensor module (top right side of engine) Lock Malfunction (service engine soon) indicator Nca Of engine) Off Oxygen sensor (in exhaust manifold) Pnk Pnk b Provisions Red Run Start Vehicle speed sensor (left rear of transmission) Vehicle speed sensor buffer (behind right side of i/p)
6.5L 6.5L (VIN F), Engine Performance Wiring Diagrams (2 of 2) for GMC Forward Control P1994 3500 List of elements for 6.5L (VIN F), Engine Performance Wiring Diagrams (2 of 2) for GMC Forward Control P1994 3500: 67 "service engine soon" lamp "service throttle" lamp (no location available) (on brake (upper rear of engine) A/c sig A10 A11 A12 Air conditioning system All times Alt fuse 20a App 2 sens 5v ref App 3 sens sig B10 B11 B12 Baro sensor (no location available) C red Crankshaft position sensor (top front of engine, inside Cruise ctrl brake sig Diagnostic request Ecm-crnk fuse 10a Fuel heater (no location available) Fuel pump (no location available) Fuel pump oil pressure switch Fuel pump relay (no location available) Fuel temp sig Fuse block Fusible link Fusible links Glow plug control relay (right rear top of engine) Glow plug sig Ground Ground (no location available) Hot at Hot at all times Hot in run, bulb test or start Hot in start or run Iat sig Ignition feed Injection pump) Injection timing stepper (its) motor (top front of engine) Instrument cluster Instrument clusters system Intake air temperature (iat) sensor (at front of engine) Its coil 1 hi Its coil 1 lo Its coil 2 hi Its coil 2 lo Left bank glow plugs Manifold absolute pressure sensor (no location available) Pedal Pnk Powertrain control module (pcm) (no location available) Red Right bank glow plugs Starting/ charging system Stop fuse 15a Stop lamp/ cruise control brake switch (on brake pedal support) Support) Switch Tan Tcc brake Wait lamp Wastegate sol ctrl Wastegate solenoid (left rear top of engine) 6.5L (VIN Y), Engine Performance Wiring Diagrams, M/T for GMC Forward Control P1994 3500 List of elements for 6.5L (VIN Y), Engine Performance Wiring Diagrams, M/T for GMC Forward Control P1994 3500: 35 (18 ga-rust) (no location available) (on starter motor) Accy Alt fuse 20a Bulb test Cold advance fast idle temperature switch (right rear of engine) Cold advance solenoid (top front of engine) Fast idle solenoid (top left side of engine) Fuel heater (top rear of engine) Fuel shut- off solenoid (top front of engine) Fuse block Fusible link (12 ga- Fusible link (20 ga- Fusible links G125 (front of engine) Glow plug controller (left side of engine) Glow plug wait lamp Ground (no location available) Hot at all times Hot in run or start Hot in start Instrument cluster Left bank glow plugs Lock Nca Off Pnk Red Right bank glow plugs Run Rust) Start Water- in-fuel indicator Water-in fuel sensor (top rear of engine)
7.4L 7.4L (VIN N), Engine Performance Wiring Diagrams, A/T Commercial Chassis and Motorhome (2 of 3) for GMC Forward Control P1994 3500 List of elements for 7.4L (VIN N), Engine Performance Wiring Diagrams, A/T Commercial Chassis and Motorhome (2 of 3) for GMC Forward Control P1994 3500: 33 (center rear 4.3l and 7.4l 5.7l Accy Alt fuse 20a Bulb test Distributor Engine coolant temperature sensor (top front of engine) Fuse block G125 (at generator bracket) Hot at all times Hot in run, bulb test, or start Ignition coil (top right rear of engine) Ignition switch Instrument cluster Knock sensor (left rear of engine, near oil pressure sender) Knock sensor module (top right side of engine) Lock Malfunction (service engine soon) indicator Manifold absolute pressure sensor (above valve cover) Nca Of engine) Off Pnk Pnk b Pnk/ Provisions for tachometer Red Run Start Tcc/brake switch (on brake pedal support bracket) Throttle position sensor (on throttle body) Trans fuse 10a 7.4L (VIN N), Engine Performance Wiring Diagrams, A/T Commercial Chassis and Motorhome (3 of 3) for GMC Forward Control P1994 3500 List of elements for 7.4L (VIN N), Engine Performance Wiring Diagrams, A/T Commercial Chassis and Motorhome (3 of 3) for GMC Forward Control P1994 3500: 28 1-2 shift soleniod 2-3 shift soleniod 4.3l 5.7l and 7.4l Bh conn pin h2 Data link connector (behind left side of shipping panel) Ecm-bat fuse 10a Electronic 4-speed automatic overdrive transmission Fuel pump and sender (in fuel tank) Fuel pump oil pressure switch (top rear of engine) Fuel pump prime connector (no location available) Fuel pump relay (lower left side of shipping panel) Fuse block G125 (at generator bracket) G125 (front of engine near thermostat) G402 (left frame rail near fuel tank) Heated oxygen sensor (in exhaust manifold) Hot at all times Nca Oxygen sensor (in exhaust manifold) Pnk Pressure control solenoid Range mode selector Red Torque converter clutch solenoid Trans- mission temp sensor Vehicle speed sensor (left rear of transmission) Vehicle speed sensor buffer (behind right side of i/p) 7.4L (VIN N), Engine Performance Wiring Diagrams, A/T P/G Cutaway (2 of 3) for GMC Forward Control P1994 3500 List of elements for 7.4L (VIN N), Engine Performance Wiring Diagrams, A/T P/G Cutaway (2 of 3) for GMC Forward Control P1994 3500: 29 (center rear Accy Bulb test Distributor Engine coolant temperature sensor (top front of engine) Fuse block Gages fuse 20a Hot at all times Hot in run, bulb test, or start Ignition coil (top right rear of engine) Ignition switch Instrument cluster Knock sensor (left rear of engine, near oil pressure sender) Lock Malfunction (service engine soon) indicator Manifold absolute pressure sensor (above valve cover) Nca Of engine) Off Pnk Pnk b Pnk/ Provisions for tachometer Red Run Start Tcc/brake switch (on brake pedal support bracket) Throttle position sensor (on throttle body) Trans fuse 10a 7.4L (VIN N), Engine Performance Wiring Diagrams, A/T P/G Cutaway (3 of 3) for GMC Forward Control P1994 3500 List of elements for 7.4L (VIN N), Engine Performance Wiring Diagrams, A/T P/G Cutaway (3 of 3) for GMC Forward Control P1994 3500: 24 1-2 shift soleniod 2-3 shift soleniod Bh conn pin h2 Data link connector (behind left side of shipping panel) Electronic 4-speed automatic overdrive transmission Fuel pump and sender (in fuel tank) Fuel pump fuse 20a Fuel pump oil pressure switch (top rear of engine) Fuel pump prime connector (top of cowl) Fuel pump relay (lower left side of shipping panel) Fuse block G125 (at generator bracket) G125 (front of engine near thermostat) G402 (left frame rail near fuel tank) Hot at all times Nca Pnk Pressure control solenoid Range mode selector Red Torque converter clutch solenoid Trans- mission temp sensor Vehicle speed sensor (left rear of transmission) Vehicle speed sensor buffer (behind right side of i/p)
GROUND DISTRIBUTION Ground Distribution Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500 List of elements for Ground Distribution Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500: 71 manual transmission (at generator bracket) (rear of cylinder head) (right frame rail, near battery) (right rear of engine) ** with schoolbus equipment A12 Battery (gasoline engines) Brake/ transmission shift interlock relay Brake/ transmission shift interlock solenoid C212 C250 C251 C252 Convenience center Data link conn- ector Data link connector Daytime running lamp module Daytime running lamp relay Egr electronic vacuum regulator solenoid valve Engine coolant level sensor For left side marker For right side marker Fuel cycle module Fuel heater Fuel pump Fuel pump relay G# n/a (in i/p harness) G# n/a (in forward lamps harness) G# n/a (in i/p harness) G# n/a (in rear lamps harness) G#s n/a (in forward lamps harness) G105 G109 (right side of radiator support) G110 (front of left cylinder head) G117 G119 (front of right cylinder head) G125 G125 (at generator bracket) G125 (front of engine) G125 (front of engine) G402 (along left frame rail, near fuel tank) Glow plug controller Heated oxygen sensor I/p cluster Knock sensor system module Left (or rear ) battery Left high/ low headlamp Not used Panel dimmer switch Park brake switch Powertrain control module (pcm) Provisions provisions Right (or front ) battery Right high/ low headlamp Starter relay Tan Transmission control module Transmission range indicator lamp Vehicle speed sensor buffer W/ automatic transmission W/ automatic transmissions W/ daytime running lights W/ diesel engine W/ diesel engines W/ gasoline engines W/ l05 engine W/ schoolbus equipment Washer pump Water- in-fuel sensor Wiper motor Ground Distribution Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500 List of elements for Ground Distribution Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500: 61 (canada only) A/c compressor A/c compressor pressure cycling switch A12 Audio alarm module Battery Blower motor Blower relay Brake/ shift interlock relay Brake/ transmission shift interlock solenoid Bus bar ground C228 C236a C250 Cigarette lighter Cruise control module Data link conn- ector Daytime running lamps module Daytime running lamps relay Egr electronic vacuum regulator valve solenoid Flow switch (brakes) Fuel pump Fuel pump relay G110 (left lower front of engine) G111 (engine compartment behind battery) G111 (engine compartment, behind battery) G114 (at rear of left cylinder head) G123 (engine compartment, above right headlamp) G125 (top right front of engine at thermostat housing) G202 (at bus bar ground) G402 (along left frame rail, on rear crossmember) Heater control lamp In-line diode Instrument cluster Left high beam headlamp Left horn Left low beam headlamp Left park and turn lamp Left park lamp Left power window switch Left side marker lamp Left tail stop and turn lamp License lamp ground (from body builder) Light switch Power door lock relay Powertrain control module (pcm) Provisions for clearance lamps Provisions for rear marker lamps Radio Right high beam headlamp Right horn Right low beam headlamp Right park and turn lamp Right park lamp Right side marker lamp Right tail stop and turn lamp Safety belt retractor switch Tan Vehicle speed sensor buffer Windshield washer pump Windshield wiper motor module Ground Distribution Wiring Diagram, Motorhome Chassis for GMC Forward Control P1994 3500 List of elements for Ground Distribution Wiring Diagram, Motorhome Chassis for GMC Forward Control P1994 3500: 38 (right frame rail near battery) A/c compressor clutch A12 Audio alarm module Auxilliary cooling fan Auxilliary cooling fan coolant pressure switch Battery Brake/ transmission shift interlock relay Brake/ transmission shift interlock solenoid C212 C250 Cruise control module Data link conn- ector Daytime running lamps module Daytime running lamps relay Fuel pump Fuel pump relay G# n/a (at left shipping panel) G# n/a (at left rear frame rail) G#s n/a (in forward lamps harness) G105 G117 (right rear of engine) G125 (top right front of engine) G402 (at left rear frame rail) Headlamp dimmer switch I/p cluster Left high beam headlamp Left high/low beam headlamp Powertrain control module (pcm) Provisions for left side marker lamp Provisions for right side marker lamp Right high beam headlamp Right high/low beam headlamp Tan Transmission range indicator lamp Vehicle speed sensor buffer W/ daytime running lights Wiper washer switch
HEADLIGHTS Headlamps Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500 List of elements for Headlamps Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500: 15 (in forward lamps harness) (in i/p harness) Head Headlamp dimmer switch Hi beam indicator Hot at all times Instrument cluster Left hi headlamp assembly Light switch Off Park Right hi headlamp assembly Tan Tan b Tan c Headlamps Wiring Diagram, Commercial Chassis with DRL for GMC Forward Control P1994 3500 List of elements for Headlamps Wiring Diagram, Commercial Chassis with DRL for GMC Forward Control P1994 3500: 30 (at park brake, under left side of i/p) (in forward lamps harness) (in i/p harness) Bulb check Daytime running lamp indicator Daytime running lamps module (in i/p harness) Daytime running lamps relay (in i/p harness) Fog lamps Fuse block Ground Head Headlamp dimmer switch Headlight switch assembly Hi beam feed Hi beam indicator Horn/dm fuse 15a Hot at all times Hot in run Htr fuse 25a Ignition Instrument cluster Lamp feed Left headlamp assembly Off Output to relay Park Park brake warning switch Provisions for fog lamps Right headlamp assembly Tan Headlamps Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500 List of elements for Headlamps Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500: 18 (at bus Bar ground) G111 (engine compartment, behind battery) G202 Head Headlamp dimmer switch Hi beam indicator Hot at all times Instrument cluster Left high beam headlamp assembly Left low beam headlamp assembly Light switch Off Park Right high beam headlamp assembly Right low beam headlamp assembly Tan Tan a Headlamps Wiring Diagram, Cutaway Chassis with DRL for GMC Forward Control P1994 3500 List of elements for Headlamps Wiring Diagram, Cutaway Chassis with DRL for GMC Forward Control P1994 3500: 32 (on park brake support bracket) Bulb check C12 C17 Daytime running lamp indicator Daytime running lamps module (behind left side of i/p) Daytime running lamps relay (behind left side of i/p, above steering column) Drl fuse 10a Fuse block G111 (engine compartment, behind battery) G202 (at bus bar ground) Gauges fuse 20a Ground Head Headlamp dimmer switch Headlight switch assembly Hi beam feed Hi beam indicator Hot at all times Hot in run or start Ignition Instrument cluster Lamp feed Left high beam headlamp Left low beam headlamp Off Output to relay Park Park brake warning switch Right high beam headlamp Right low beam headlamp Tan Headlamps Wiring Diagram, Motor Home Chassis for GMC Forward Control P1994 3500 List of elements for Headlamps Wiring Diagram, Motor Home Chassis for GMC Forward Control P1994 3500: 16 (at left shipping panel) (forward lamps harness) Head Headlamp dimmer switch Hi beam indicator Hot at all times Instrument cluster Left hi headlamp assembly Left lower head- lamp (w/ hpr) Light switch Off Park Right hi headlamp assembly Right lower head- lamp (w/ hpr) Tan Tan c Headlamps Wiring Diagram, Motor Home Chassis with DRL for GMC Forward Control P1994 3500 List of elements for Headlamps Wiring Diagram, Motor Home Chassis with DRL for GMC Forward Control P1994 3500: 34 (at left shipping panel) (at park brake, under left side of i/p) (in forward lamps harness) Bulb check Daytime running lamp cutoff relay (w/ hpr) (location not available) Daytime running lamp indicator Daytime running lamps module (in i/p harness) Daytime running lamps relay (in i/p harness) Fog lamps Fuse block G114 (left rear of engine) Ground Head Headlamp dimmer switch Headlight switch assembly Hi beam feed Hi beam indicator Horn/dm fuse 15a Hot at all times Hot in run or start Htr fuse 25a Ignition Instrument cluster Lamp feed Left headlamp assembly Left lower headlamp (w/ hpr) Off Output to relay Park Park brake warning switch Provisions for fog lamps Right headlamp assembly Right lower headlamp (w/ hpr) Tan
HORN Horn Wiring Diagram for GMC Forward Control P1994 3500 List of elements for Horn Wiring Diagram for GMC Forward Control P1994 3500: 8 (in i/p harness) Fuse block Horn (in forward lamps harness) Horn relay Horn switch Horn/dm fuse 15a Hot at all times Steering wheel (commercial chassis) turn signal switch (motorhome chassis) Horn Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500 List of elements for Horn Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500: 10 (in i/p harness) A-note horn (on left radiator support) F-note horn (on left radiator support) Fuse block G111 (left front of engine compartment, behind battery) Horn relay Horn switch Horn/dm fuse 15a Hot at all times Turn signal switch
INSTRUMENT CLUSTER Instrument Cluster Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500 List of elements for Instrument Cluster Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500: 78 (in i/p harness) *a5-4.3l(m/t) & 5.7l(m/t) e6-4.3l(a/t), 5.7l(a/t) & 7.4l Accy Alarm (in hydro- boost warning harness) Alt fuse 20a Audio alarm module (convenience center) Brake fluid level switch (rear of engine compt) Bulb test C251 C253 C292 C299 Coolant temp. Coolant temp. gauge Daytime running lamps module Daytime running lamps module (in i/p harness) Daytime running lamps relay Daytime running lights ind. (w/ drl) Diesel only Engine coolant level indicator module (in i/p harness) Engine coolant level indicator probe (in radiator) Engine coolant temperature sender (left side of engine) Exterior lights system Fasten belts ind. Flasher unit (in hydro- boost warning harness) Flow switch (at power brake booster module) Fuel gauge Fuel level Fuel pump & sender (top rear of engine) Fuel pump/ oil pressure switch & sender (left side of engine) Fuse block G125 (front of engine) Gauges fuse 20a Glow plug controller (rear of engine) Glow plugs ind. (diesel) Gnd Headlights system Hi beam ind. Hot in run Hot in run, bulb test or start Hot w/ lamp switch in park or head Hydro- boost pressure warning switch (in hydro- boost warning harness) I/p ground (in i/p harness) Ign Ignition switch Illum. Illum. lamps Instr-lps fuse 5a Instrument cluster Left turn ind. Lock Low coolant ind. (diesel) Mal- function ind. Off Oil press. gauge Oil press. signal Park brake ind. Park brake switch Pnk Powertrain control module (left side of shipping panel) Right turn ind. Run Service brakes ind. Service trans- mission ind. (diesel) Solid state Speed- ometer Start Tan Tan/ Transmission control module (left side of shipping panel) Vehicle speed Vehicle speed sensor (left rear of transmission) Vehicle speed sensor buffer module (right side of i/p) Volt- meter W/ drl W/o drl Water in fuel ind. (diesel) Water-in-fuel sensor (rear of engine) Instrument Cluster Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500 List of elements for Instrument Cluster Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500: 64 (7.4l-top right front of engine) (along left frame rail, on rear crossmember) (at bus bar ground) (in fuel tank) Audio alarm module (convenience Brake ind. Brake pressure warning switch (on left frame rail) Brake warning alarm buzzer (behind left side of i/p, near fuse block) C208 C301 Center) Coolant temp. Coolant temp. gauge Daytime running lamps ind. (w/ drl) Daytime running lamps module (behind left side of i/p, above steering column) Daytime running lamps relay (behind left side of i/p, above steering column) Electronic delay module (behind left side of i/p, Engine coolant temperature sensor (5.7l-lower left side of engine) Exterior lights system Flow switch (near power steering pump) Fuel gauge Fuel level Fuel pump & sender Fuel pump oil pressure switch & sender (5.7l-top rear of engine) (7.4l-lower left side of engine) Fuse block G202 G409 Gages fuse 20a Gnd Headlights system Hi beam ind. Hot in run, bulb test or start Hot w/ lamp switch in park or head Hydro-boost pressure warning switch (near master cylinder) Ign Ignition switch Illum. Illum. lamp Illum. lamps In-line diode (behind left side of i/p, above fuse block) In-line diode (behind left side of i/p, above steering column) Instr lps fuse 5a Instrument cluster Left turn ind. Low coolant ind. (not used) Mal- function ind. Oil press. gauge Oil press. signal On park brake support bracket) Output speed sensor (left rear of transmission) Park brake warning switch Pnk/ Powertrain control module (under driver's seat) Resistor (1.5k ohms, 0.5 watt) Right turn ind. Safety belt ind. Sheet metal ground Speed- ometer Tan Vehicle speed Vehicle speed sensor buffer (behind left side of i/p) Volt- meter W/ drl W/o drl Instrument Cluster Wiring Diagram, Motorhome Chassis for GMC Forward Control P1994 3500 List of elements for Instrument Cluster Wiring Diagram, Motorhome Chassis for GMC Forward Control P1994 3500: 64 (at left shipping panel) (in fuel tank) (left front of engine) (left rear frame rail) (right frame rail, near battery) (top right side of Accy Alt fuse 20a Audio alarm module (convenience center) Brake ind. Brake pressure warning switch (near master cylinder) Bulb test C205 C251 Coolant temp. Coolant temp. gauge Daytime running lamps module Daytime running lamps module (top right side of Daytime running lamps relay Daytime running lights ind. (w/ drl) Engine coolant temperature sender Exterior lights system Fuel gauge Fuel level Fuel pump & sender Fuse block G101 G409 Gnd Headlights system Hi beam ind. Hot in run, bulb test or start Hot w/ lamp switch in park or head I/p ground Ign Ignition switch Illum. Illum. lamps Instr-lps fuse 5a Instrument cluster Left turn ind. Lock Mal- function ind. Off Oil press. gauge Oil press. signal Oil pressure switch & sender (top rear of engine) Park brake ind. Park brake warning switch Powertrain control module (left side of i/p, behind shipping panel) Right turn ind. Run Safety belt ind. Shipping harness) Speed- ometer Start Tan Tan/ Vehicle speed Vehicle speed sensor (on output shaft of transmission) Vehicle speed sensor buffer (inside left side of shipping panel) Volt- meter W/ drl W/o drl
INTERIOR LIGHTS Interior Light Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500 List of elements for Interior Light Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500: 21 (5) bulbs C17 C261 Dim Exterior lights system Fuse block G200 (left side of i/p) Head Headlight switch assembly Heater & a/c control illumination lamps High Horn/dm fuse 15a Hot at all times I/p lps fuse 5a Instrument cluster Light switch Off Panel dimmer switch assembly Park Provisions for dome lamps Tail lps fuse 20a Interior Light Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500 List of elements for Interior Light Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500: 27 (6) bulbs Audio alarm module C17 C261 Dim Dome switch Front dome lamp Fuse block G200 (left side of i/p) Head Headlight switch assembly High Horn/dm fuse 20a Hot at all times I/p lps fuse 5a Instrument cluster Left door jamb switch Light switch Lights on input Off Panel dimmer switch assembly Park Provisions for rear dome lamp Radio Solid state Tail lps fuse 20a Trans- mission range indicator lamp Interior Light Wiring Diagram, Motorhome Chassis for GMC Forward Control P1994 3500 List of elements for Interior Light Wiring Diagram, Motorhome Chassis for GMC Forward Control P1994 3500: 22 (6) bulbs C218 Dim Dome lamp Dome switch Exterior lights system Fuse block G114 (left rear of engine) G200 (left side of i/p) Head Headlight switch assembly High Horn/dm fuse 15a Hot at all times I/p lps fuse 5a Instrument cluster Light switch Off Panel dimmer switch assembly Park Tail lps fuse 20a Transmission range indicator lamp
POWER DISTRIBUTION Power Distribution Wiring Diagram, Commercial Chassis (Diesel) (1 of 2) for GMC Forward Control P1994 3500 List of elements for Power Distribution Wiring Diagram, Commercial Chassis (Diesel) (1 of 2) for GMC Forward Control P1994 3500: 68 (warning systems) Acc-radio fuse 10a Accy Battery junction block Body builder's Brake warning system Bulb test C16 C298 C299 Clutch start switch Daytime running lamps Daytime running lamps relay Ecm-bat fuse 10a Engine coolant level indicator module From panel dimmer switch From park brake warning switch Fuel pump oil pressure switch Fuel pump relay Fuse block Fuse block & glow plug controller Fusible link e Fusible link f Gages fuse 20a Generator Hazard flasher Headlight switch assembly Horn relay Horn/dm fuse 15a Htr fuse 25a I/p cluster Ignition switch Instr-lps fuse 5a Instrument cluster printed circuit Junction block Left rear battery Link a fusible Link b fusible Link c fusible Link d fusible Lock Module Off Pnk Powertrain control module (pcm) Provisions for dome lamps Red Relay Right front battery Rst 10ga Rst 12ga Rst 14ga Rst 16ga Run Shunt Start Starter relay Starter solenoid Stop- hz fuse 15a Stoplamp switch Tail lps fuse 20a To glow plug controller Transmission range indicator lamp W/ auto transmission W/ manual transmission only Wiper fuse 25a Wiper motor Wiper switch Power Distribution Wiring Diagram, Commercial Chassis (Diesel) (2 of 2) for GMC Forward Control P1994 3500 List of elements for Power Distribution Wiring Diagram, Commercial Chassis (Diesel) (2 of 2) for GMC Forward Control P1994 3500: 30 Alt fuse 20a Audio alarms Backup lamp switch (auto trans) Backup lamp switch (manual trans) C128 C16 C190 Cold advance fast idle temperature switch Ecm-crank fuse 10a From fusible link a From ignition switch Fuel heater Fuse block Generator Glow plug controller I/p cluster Pnk Red Tcc/ brake switch Tcm Trans fuse 10a Transmission Transmission only Turn signal flasher Turn-b/u fuse 15a Vehicle speed sensor buffer Water-in-fuel sensor With automatic * With automatic transmission only With manual transmission only Power Distribution Wiring Diagram, Commercial Chassis (Gasoline) (1 of 2) for GMC Forward Control P1994 3500 List of elements for Power Distribution Wiring Diagram, Commercial Chassis (Gasoline) (1 of 2) for GMC Forward Control P1994 3500: 69 (warning systems) 15a Acc bus Acc-radio fuse 10a Accy Alt, ecm-crank, turn-b/u, injector fuses Alt, ecm-crank, turn-b/u, trans, injector fuses Automatic transmission B batt bus Battery Battery junction block Body builder's Brake warning system Bulb test C16 C298 C299 Clutch pedal switch Crank fuse 10a Daytime running lamps Daytime running lamps relay Ecm-bat fuse 10a Fuel cycle module Fuel pump oil pressure switch Fuel pump relay Fuse block Fusible Fusible link c rst 10ga Gages fuse 20a Generator Hazard flasher Headlight switch assembly Horn relay Horn/dm fuse Htr bus Htr fuse 25a I/p cluster Ignition switch Instr-lps fuse 5a Junction block Lock Manual transmission Module Off Panel dimmer switch (interior lights system) Park brake warning switch Pnk Powertrain control module (pcm) Powertrain control module (pcm) (with manual transmission only) Provisions for dome lamps Red Relay Rst 14ga link b Rst 16ga fusible link d Rst 16ga link a fusible Run Shunt Start Starter solenoid Stop-hz fuse 15a Stoplamp switch Tail lps fuse 20a Trans Transmission range indicator lamp W/ auto Wiper fuse 25a Wiper motor Wiper switch With manual transmission only Power Distribution Wiring Diagram, Commercial Chassis (Gasoline) (2 of 2) for GMC Forward Control P1994 3500 List of elements for Power Distribution Wiring Diagram, Commercial Chassis (Gasoline) (2 of 2) for GMC Forward Control P1994 3500: 38 (auto trans) (except vin k w/ manual transmission) (manual trans) All others Alt fuse 20a Audio alarm module Backup lamp switch Convenience center E15 Ecm-crank fuse 10a Egr electronic vacuum Egr solenoid Evaporative canister purge solenoid Fuse block Generator Heated oxygen sensor (vin z w/ manual transmission) I/p cluster Idle speed control actuator Ignition coil Ignition switch Inj fuse 7.5a Injector #1 Injector #2 Knock sensor system (w/ manual transmission) Pcm Pnk Red Regulator solenoid valve (vin k only) Tcc/ brake switch Trans fuse 10a Transmission Turn signal flasher Turn-b/u fuse 15a Vehicle speed sensor buffer Vehicle speed sensor buffer (vin k w/ manual transmission) Vin k with heavy duty automatic transmission Vin n w/ automatic transmission W/ automatic transmission Power Distribution Wiring Diagram, Cutaway Chassis (1 of 2) for GMC Forward Control P1994 3500 List of elements for Power Distribution Wiring Diagram, Cutaway Chassis (1 of 2) for GMC Forward Control P1994 3500: 67 20a 30a Accy Audio alarm module Backup lamp switch Battery Battery junction block Bulb test C112 C214 C215 Cigarette lighter Daytime running lamps relay Dome lamp Door lock relay Drl fuse 10a E16 Fuel pump Fuel pump fuse 20a Fuel pump oil pressure switch Fuse block Fusible Fusible link G202 (at bus bar ground) Generator Hazard flasher Heater blower switch Heater control lamps Horn relay Horn/dm fuse Htr a/c fuse 25a Ignition switch Instr-lps fuse 5a Instrument cluster printed circuit Left door lock switch Left power window switch Light switch Link Lock Off Pnk Powertrain control module (pcm) Pwr acc circuit breaker Pwr wdo circuit breaker 30a Radio Radio fuse 10a Red Right door lock switch Right power window switch Rst 10ga Rst 14ga Rst 16ga Rst 18ga Run Shunt Start Starter solenoid Stop-hz fuse 20a Stoplamp switch Tail lps fuse To emci, gages & trans fuses and ignition coil Transmission range indicator lamp Turn signal flasher Turn-b/u fuse 20a Windshield wiper motor module Windshield wiper/ washer switch Wiper fuse 25a Power Distribution Wiring Diagram, Cutaway Chassis (2 of 2) for GMC Forward Control P1994 3500 List of elements for Power Distribution Wiring Diagram, Cutaway Chassis (2 of 2) for GMC Forward Control P1994 3500: 30 Audio alarm module Brake warning alarm buzzer C118 C304 Daytime running lamps module Daytime running lamps relay E15 Ecmi fuse 20a Egr electronic vacuum regulator solenoid valve Evaporative emissions canister purge valve F15 Fuse block Gages fuse 10a Generator Idle speed control actuator Ignition coil Ignition switch Injector #1 Injector #2 Instrument cluster Mt1 transmission Pnk Powertrain control module (pcm) Powertrain control module (pcm) (vin k only) Red Shunt Tcc/ brake switch Trans fuse 10a Vehicle speed sensor buffer Vin n only Power Distribution Wiring Diagram, Motorhome Chassis (1 of 2) for GMC Forward Control P1994 3500 List of elements for Power Distribution Wiring Diagram, Motorhome Chassis (1 of 2) for GMC Forward Control P1994 3500: 64 15a Acc-radio fuse 10a Accy Audio alarm Audio alarm module Aux Aux circuit breaker 30a Auxiliary cooling Auxiliary cooling fan relay Battery Battery junction block Brake pressure warning switch Bulb test C201 C277 Daytime running lamps Daytime running lamps relay Dome lamp E16 Ecm-bat fuse 10a Fan relay From panel dimmer switch assembly (interior lights system) Fuel pump oil pressure switch Fuel pump relay Fuse block Fusible Fusible link Gages fuse 20a Generator Hazard flasher Headlight switch assembly Horn relay Horn/dm fuse Htr fuse 25a I/p cluster Ignition switch Instr-lps fuse 5a Instrument cluster Link Lock Lps bus Module Off Park brake warning switch Pnk Powertrain control module (pcm) Pwr circuit breaker 30a Red Relay Rst 10ga Rst 14ga Rst 16ga Rst 18ga Run Shunt Start Starter motor Stop-hz fuse 15a Stoplamp switch Tail lps fuse 20a To alt, ecm-crank, turn-b/u, trans & injector fuses and ignition coil Transmission position indicator lamp Wiper fuse 25a Wiper switch Power Distribution Wiring Diagram, Motorhome Chassis (2 of 2) for GMC Forward Control P1994 3500 List of elements for Power Distribution Wiring Diagram, Motorhome Chassis (2 of 2) for GMC Forward Control P1994 3500: 29 Alt fuse 20a Audio alarm module Backup lamp switch Cruise control brake switch Cruise control module Cruise control switch E15 Ecm-crank fuse 10a Evaporative emissions canister purge solenoid F15 Fuse block Generator Idle speed control actuator Ignition coil Ignition switch Inj fuse 7.5a Injector #1 Injector #2 Instrument cluster printed circuit Linear egr solenoid valve Pnk Powertrain control module (pcm) Red Tcc/ stoplamp switch Trans fuse 10a Transmission Turn signal flasher Turn-b/u fuse 15a Vehicle speed sensor buffer
POWER DOOR LOCKS Power Door Lock Wiring Diagram for GMC Forward Control P1994 3500 List of elements for Power Door Lock Wiring Diagram for GMC Forward Control P1994 3500: 12 Bus bar ground (near fuse block) Door lock relay (behind left side of i/p) Fuse block Hot at all times Left door lock motor Left door lock switch Lock Pwr acc circuit breaker 30a Right door lock motor Right door lock switch Tan Unlock
POWER WINDOWS Power Window Wiring Diagram for GMC Forward Control P1994 3500 List of elements for Power Window Wiring Diagram for GMC Forward Control P1994 3500: 14 1994 vftc c Fuse block G202 (at bus bar ground Hot in run Left front switch Left front window motor Left power window master switch Pnk Pnk a Pwr wdo circuit breaker 30a Right front switch Right front window motor Right front window switch Tan
SHIFT INTERLOCKS Shift Interlock Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500 List of elements for Shift Interlock Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500: 14 (closed in park) (on steering Backup lamp switch Brake shift interlock relay (on steering column) Brake/transmission shift interlock solenoid (on steering column) Column) E13 Fuse block G200 (at bus bar ground) Hot in acc or run Hot in start or run Powertrain contol module (left side of vehicle, behind shipping panel) Tcc/ brake switch (on brake pedal support bracket) Trans fuse 10a Turn b/u fuse 15a Shift Interlock Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500 List of elements for Shift Interlock Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500: 15 (closed in park) (on steering Backup lamp switch Brake shift interlock relay (on steering column) Brake/transmission shift interlock solenoid (on steering column) Column) E13 Fuse block G200 (at bus bar ground) Hot in acc or run Hot in start or run Powertrain control module (left side of vehicle, behind shipping panel) Tcc/ brake switch (on brake pedal support bracket) Trans fuse 10a Turn b/u fuse 15a Turn signal flasher (on fuse block) Shift Interlock Wiring Diagram, Motorhome Chassis for GMC Forward Control P1994 3500 List of elements for Shift Interlock Wiring Diagram, Motorhome Chassis for GMC Forward Control P1994 3500: 15 (closed in park) (on steering Backup lamp switch Brake shift interlock relay (on steering column) Brake/transmission shift interlock solenoid (on steering column) Column) E13 Fuse block G200 (at bus bar ground) Hot in acc or run Hot in start or run Powertrain control module (left side of vehicle, behind shipping panel) Tcc/ brake switch (on brake pedal support bracket) Trans fuse 10a Turn b/u fuse 15a Turn signal flasher (on fuse block)
STARTING/CHARGING Charging Wiring Diagram, Commercial Chassis (Diesel) for GMC Forward Control P1994 3500 List of elements for Charging Wiring Diagram, Commercial Chassis (Diesel) for GMC Forward Control P1994 3500: 30 (closes with low or high voltage; gen fault) (in i/p harness) (left side of shipping panel) (not (not used) (right front cylinder head) (right side of radiator support) Alt fuse 20a Bat Battery Battery junction block C205 Field (rotor) Fuse block G109 G119 G201 Generator (right front of engine) Hot in run, bulb test or start Instrument cluster Power distribution Rectifier bridge Red Regulator solid-state Stator Sw bat Turn on input Used) Volt sense input Volt- meter Charging Wiring Diagram, Commercial Chassis (Gasoline) for GMC Forward Control P1994 3500 List of elements for Charging Wiring Diagram, Commercial Chassis (Gasoline) for GMC Forward Control P1994 3500: 32 (at generator bracket) g114 (on right frame rail rear of engine (school bus ground) (closes with low or high voltage; gen fault) (in i/p harness) (left side of shipping panel) (not (not used) (rear of cylinder head) (school bus ground) (right side of radiator support) Alt fuse 20a Bat Battery Battery junction block C205 Field (rotor) Fuse block G101 G109 G115 G201 Generator (right front of engine) Hot in run, bulb test or start Instrument cluster Power distribution Rectifier bridge Red Regulator solid-state Stator Sw bat Turn on input Used) Volt sense input Volt- meter Charging Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500 List of elements for Charging Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500: 33 (at bus bar ground) (closes with low or high voltage; gen fault) (engine compartment, behind battery (left lower (left side of shipping panel) (not (not used) Bat Battery Battery junction block C17 Engine) Field (rotor) Front of Fuse block Fusible link (10 ga-rust) G110 G111 G202 Gages fuse 20a Generator (right front of engine) Hot in run or start Instrument cluster Rectifier bridge Red Regulator solid-state Starter circuit Stator Sw bat Turn on input Used) Volt sense input Volt- meter Charging Wiring Diagram, Motor Home Chassis for GMC Forward Control P1994 3500 List of elements for Charging Wiring Diagram, Motor Home Chassis for GMC Forward Control P1994 3500: 25 (at left shipping panel) (closes with low or high voltage; gen fault) (left side of shipping panel) (not (not used) Aalt fuse 20a Bat Battery Battery junction block Field (rotor) Fuse block G111 (engine compartment behind battery Generator (right front of engine) Hot in run or start Instrument cluster Rectifier bridge Red Regulator solid-state Starter circuit Stator Sw bat Turn on input Used) Volt sense input Volt- meter Starting Wiring Diagram, Commercial Chassis (Diesel) for GMC Forward Control P1994 3500 List of elements for Starting Wiring Diagram, Commercial Chassis (Diesel) for GMC Forward Control P1994 3500: 39 (at generator bracket) g114 (lower right side of engine) (on clutch pedal (on right frame rail rear of engine) (school bus ground) (right side of radiator support) A/t Accy Bat Battery Battery junction block (left side of Bulb test C298 C299 Clutch start switch Fusible link (20 ga. rust) Fusible link c (16 ga. rust) Fusible link e (20 ga. rust) G100 G101 G115 (rear of cylinder head) (school bus G125 (front of engine) Generator (front of engine) Glow plug controller (top rear of engine) Ground) Hold-in winding Ignition switch Lock M/t Off Pull-in winding Red Run Shipping panel) Solenoid contacts Start Starter motor Starter relay (lower left side of engine) Starter solenoid Support bracket) Starting Wiring Diagram, Commercial Chassis (Gasoline) for GMC Forward Control P1994 3500 List of elements for Starting Wiring Diagram, Commercial Chassis (Gasoline) for GMC Forward Control P1994 3500: 36 (at generator bracket) g114 (lower right side of engine) (on clutch pedal (on right frame rail rear of engine) (school bus ground) (right side of radiator support) A/t Accy Bat Battery Battery junction block (left side of Bulb test C298 C299 Clutch start switch Fusible link b (14 ga. rust) Fusible link e (20 ga. rust) G100 G101 G115 (rear of cylinder head) (school bus Generator (front of engine) Ground) Hold-in winding Ignition switch Lock M/t Off Power distribution (fuse block) Pull-in winding Red Run Shipping panel) Solenoid contacts Start Starter motor Starter solenoid Support bracket) Starting Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500 List of elements for Starting Wiring Diagram, Cutaway Chassis for GMC Forward Control P1994 3500: 24 (left lower front of engine) (lower right side of engine) Accy Battery Battery junction block (left side of Bulb test C214 C215 Distribution Fusible link (16 ga rust) G110 G111 (engine compartment behind battery) Hold-in winding Ignition switch Lock Off Power red Pull-in winding Red Run Solenoid contacts Start Starter motor Starter solenoid Starting Wiring Diagram, Motor Home Chassis for GMC Forward Control P1994 3500 List of elements for Starting Wiring Diagram, Motor Home Chassis for GMC Forward Control P1994 3500: 24 (lower right side of engine) (right frame rail near battery) Accy Bat Battery Battery junction block (left side of Bulb test C201 C277 Fusible link b (14 ga. rust) Fusible link e (20 ga. rust) G105 Generator (front of engine) Hold-in winding Ignition switch Lock Off Pull-in winding Red Run Solenoid contacts Start Starter motor Starter solenoid
TRANSMISSION
4.3L 4.3L (VIN Z), Transmission Wiring Diagram, 4L80-E for GMC Forward Control P1994 3500 List of elements for 4.3L (VIN Z), Transmission Wiring Diagram, 4L80-E for GMC Forward Control P1994 3500: 63 (behind left side of shipping panel) data link connector 1-2 shift sol 1-2 shift sol ctrl 2-3 shift sol 2-3 shift sol ctrl A14 A15 All times Battery Brake signal C11 C12 C13 C250 C251 Diagnostic test E11 E13 E15 E16 Ecm bat fuse 10a Ecm-crnk fuse 10a Ect signal Electronic 4-speed automatic overdrive transmission Engine coolant temp sens (top right side of eng) F10 F12 F13 F14 F15 Fuse block G125 (front of engine) Ground Hot at Hot in run, bulb test or start Ignition Pcs hi Pcs lo Pnk Powertrain control module (left side of shipping panel) Pressure control solenoid Range mode selector Range signal a Range signal b Range signal c Red Sensor ground Serial data Tcc sol Tcc sol ctrl Tcc/brake switch (on brake pedal support arm) Tft signal Throttle position sensor (top right side of eng) Tp reference Tp signal Trans fuse 10a Trans output speed Trans speed sens input Trans- mission input speed sensor (left frnt of trans) Trans- mission temp Vehicle speed sensor (rear of transmission) Vehicle speed sensor buffer (behind right side of i/p) Vss signal
5.7L 5.7L (VIN K), Transmission Wiring Diagram, 4L80-E for GMC Forward Control P1994 3500 List of elements for 5.7L (VIN K), Transmission Wiring Diagram, 4L80-E for GMC Forward Control P1994 3500: 63 (behind left side of shipping panel) data link connector 1-2 shift sol 1-2 shift sol ctrl 2-3 shift sol 2-3 shift sol ctrl A14 A15 All times Battery Brake signal C11 C12 C13 C250 C251 Diagnostic test E11 E13 E15 E16 Ecm bat fuse 10a Ecm-crnk fuse 10a Ect signal Electronic 4-speed automatic overdrive transmission Engine coolant temp sens (top right side of eng) F10 F12 F13 F14 F15 Fuse block G125 (front of engine) Ground Hot at Hot in run, bulb test or start Ignition Pcs hi Pcs lo Pnk Powertrain control module (left side of shipping panel) Pressure control solenoid Range mode selector Range signal a Range signal b Range signal c Red Sensor ground Serial data Tcc sol Tcc sol ctrl Tcc/brake switch (on brake pedal support arm) Tft signal Throttle position sensor (top right side of eng) Tp reference Tp signal Trans fuse 10a Trans output speed Trans speed sens input Trans- mission input speed sensor (left frnt of trans) Trans- mission temp Vehicle speed sensor (rear of transmission) Vehicle speed sensor buffer (behind right side of i/p) Vss signal
6.5L 6.5L (VIN F), Transmission Wiring Diagram, 4L80-E for GMC Forward Control P1994 3500 List of elements for 6.5L (VIN F), Transmission Wiring Diagram, 4L80-E for GMC Forward Control P1994 3500: 75 (tft) (under right end of i/p) 1-2 shift sol 1-2 shift sol ctrl 2-3 shift sol 2-3 shift sol ctrl 4 wheel drive low sig A12 Accelerator pedal position (app) module (top of acce- lerator bracket) Alt fuse 20a App #1 App #1 sensor 5v ref App #1 sensor ground App #1 sensor sig App #2 App #2 sensor 5v ref App #2 sensor sig App #3 App #3 sensor 5v ref App #3 sensor ground App #3 sensor sig B10 Battery feed Bracket) C11 C12 C13 C14 C15 D11 Data link connector (below left side of i/p) Diagnostic request E10 E11 E13 Ecm-bat fuse 10a Ecm-crank fuse 10a Ect sig Electronic 4-speed automatic overdrive transmission Engine coolant temperature (ect) sensor (right side of engine) Fuse block G117 (right rear of engine) Hot at all times Hot in run, bulb Hot in start or run Ignition feed Pnk Powertrain control module Pressure control solenoid Pressure ctrl sol hi Pressure ctrl sol lo Range mode selector Range signal "a" Range signal "b" Range signal "c" Red Sensor Sensor ground Serial data Speed sensor (left rear side of transmission) System ground Tan Tan d Tcc sol Tcc sol ctrl Tcc/ brake switch (on brake pedal support Tcc/brake sw Test or start Trans fluid temp Trans fluid temp sig Trans fuse 10a Trans output spd sig Transfer case switch Vehicle speed sensor buffer module (under right end of i/p) Vehicle speed sig 6.5L (VIN Y), Transmission Wiring Diagram, 4L80-E for GMC Forward Control P1994 3500 List of elements for 6.5L (VIN Y), Transmission Wiring Diagram, 4L80-E for GMC Forward Control P1994 3500: 80 1-2 shift sol 1-2 shift sol ctrl 2-3 shift sol 2-3 shift sol ctrl 5 volts ref A10 A11 A12 Alt fuse 20a B10 B11 B12 Baro press sens Barometric pressure (1993 only) (left side of shipping panel) Battery feed Brake signal C10 C11 C12 C13 C14 C15 C16 C205 C276 C277 D10 D11 D12 D13 D14 D15 D16 Data link conn (under left side of i/p) Diagnostic test Ecm bat fuse 10a Ecm-crnk fuse 10a Electronic 4-speed automatic overdrive transmission Engine speed sensor (center rear top of engine) Engine speed signal Fuse block G125 Hot at all times Hot in run bulb test or start Ignition Input speed sens hi Input speed sens lo Instrument cluster Pcs hi Pcs lo Pnk Pnk d Pressure control solenoid Range mode selector Range signal a Range signal b Range signal c Red Red f Sensor Sensor ground Serial data Service trans output Service transmission indicator System ground Tcc control Tcc sol Tcc/brake switch (below left side of i/p, above brake pedal) Throttle position sensor (right side of throttle body) Tp sensor input Trans fluid temp sig Trans fuse 10a Trans- mission temp Transmission control module (tcm) (right side of i/p) Transmission input speed sensor (left front side of transmission) Vehicle spd output Vehicle speed input Vehicle speed sensor (rear of transmission) Vehicle speed sensor buffer (under right side of i/p) Vss inputs
7.4L 7.4L (VIN N), Transmission Wiring Diagram, 4L80-E for GMC Forward Control P1994 3500 List of elements for 7.4L (VIN N), Transmission Wiring Diagram, 4L80-E for GMC Forward Control P1994 3500: 63 (behind left side of shipping panel) data link connector 1-2 shift sol 1-2 shift sol ctrl 2-3 shift sol 2-3 shift sol ctrl A14 A15 All times Battery Brake signal C11 C12 C13 C250 C251 Diagnostic test E11 E13 E15 E16 Ecm bat fuse 10a Ecm-crnk fuse 10a Ect signal Electronic 4-speed automatic overdrive transmission Engine coolant temp sens (top right side of eng) F10 F12 F13 F14 F15 Fuse block G125 (front of engine) Ground Hot at Hot in run, bulb test or start Ignition Pcs hi Pcs lo Pnk Powertrain control module (left side of shipping panel) Pressure control solenoid Range mode selector Range signal a Range signal b Range signal c Red Sensor ground Serial data Tcc sol Tcc sol ctrl Tcc/brake switch (on brake pedal support arm) Tft signal Throttle position sensor (top right side of eng) Tp reference Tp signal Trans fuse 10a Trans output speed Trans speed sens input Trans- mission input speed sensor (left frnt of trans) Trans- mission temp Vehicle speed sensor (rear of transmission) Vehicle speed sensor buffer (behind right side of i/p) Vss signal
WARNING SYSTEMS Warning System Wiring Diagrams, Commercial Chassis for GMC Forward Control P1994 3500 List of elements for Warning System Wiring Diagrams, Commercial Chassis for GMC Forward Control P1994 3500: 10 (in i/p harness) Alt fuse 20a Audio alarm module (below fuse block) Fasten belts indicator Fasten belts output Fuse block Ground Hot in run or start Ignition on input Instrument cluster Warning System Wiring Diagrams, Cutaway Chassis for GMC Forward Control P1994 3500 List of elements for Warning System Wiring Diagrams, Cutaway Chassis for GMC Forward Control P1994 3500: 24 Audio alarm module (below fuse block) C16 C17 Fasten belts indicator Fasten belts output Fuse block G202 (at bus bar ground) Gages fuse 20a Ground Hot at all times Hot in run or start Hot with headlight switch in park or head Ignition on input Inst lps fuse 5a Instrument cluster Key-in warning Key-in warning buzzer switch (in left side of steering column) Left door jamb switch Lights on input Power input Safety belt input Safety belt retractor switch (in driver's safety belt buckle) Stop-hz fuse 20a Tan Warning System Wiring Diagrams, Motorhome Chassis for GMC Forward Control P1994 3500 List of elements for Warning System Wiring Diagrams, Motorhome Chassis for GMC Forward Control P1994 3500: 18 (at left shipping panel) Audio alarm module (below fuse block) Fasten belts indicator Fasten belts output Fuse block Gauges fuse 20a Ground Horn/dm fuse 15a Hot at all times Hot in run or start Hot with headlight switch in park or head Ignition on input Instr-lps fuse 5a Instrument cluster Key-in warning Lights on input Power input Safety belt input
WIPER/WASHER Front Washer/Wiper Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500 List of elements for Front Washer/Wiper Wiring Diagram, Commercial Chassis for GMC Forward Control P1994 3500: 18 Control area Delay/ speed/ wash control Fuse block Fusible link Hot in accy or run I/p ground (in i/p harness) Ign Low Mist Off Park switch Pnk Pulse Wash pulse switch Windshield washer pump Windshield wiper motor module Windshield wiper/ washer switch Wiper fuse 25a Front Washer/Wiper Wiring Diagram, Cutaway for GMC Forward Control P1994 3500 List of elements for Front Washer/Wiper Wiring Diagram, Cutaway for GMC Forward Control P1994 3500: 18 Control area Delay/ speed/ wash control Fuse block Fusible link G202 (left side of i/p) Hot in accy or run Ign Low Mist Off Park switch Pnk Pulse Wash pulse switch Windshield washer pump (left kick panel) Windshield wiper motor module (center of i/p) Windshield wiper/ washer switch Wiper fuse 25a Wiper/Washer Provisions Wiring Diagram, Motorhome Chassis for GMC Forward Control P1994 3500 List of elements for Wiper/Washer Provisions Wiring Diagram, Motorhome Chassis for GMC Forward Control P1994 3500: 12 Fuse block G114 (left rear of engine) Hot in accy or run Mist Off Pnk Provisions for wiper/washer module Pulse Pulse wiper/ washer switch Wash pulse Wiper fuse 25a Wiper motor connector
