GMC Vandura G2500 1991 - ELECTRICAL COMPONENT LOCATOR 1991 GENERAL MOTORS TRUCKS ELECTRONIC COMPONENT LOCATOR

GMC Vandura G2500 1991 - BUZZERS, RELAYS & TIMERS

GMC Vandura G2500 1991 BUZZERS, RELAYS & TIMERS LOCATION

Component	Location
A/C Compressor Clutch Relay	On right side of engine compartment firewall.
A/C-Heater Blower Relay	On evaporator case, in engine compartment.
Auxiliary Cooling Fan Relay	On radiator support panel. See Fig. 1.
Downshift Relay (4L80E)
View of Relays	On right side of firewall. See Fig. 1.
7.4L VIN N	On right side of firewall. See Fig. 2.
Fuel Pump Relay
View of Relays	At center of firewall. See Fig. 1.
4.3L VIN Z	At center of firewall. See Fig. 3.
5.0L VIN H & 5.7L VIN K	At center of firewall. See Fig. 4.
7.4L VIN N	At center of firewall. See Fig. 2.
Glow Plug Inhibit Relay	On right side of firewall.
Hazard Flasher Relay	Under left side of dash.
Horn Relay	Behind left side of dash, on harness near fuse block.
Power Door Lock Delay Relay	Behind left side of dash, above kick panel.
Power Door Lock Relay	Behind left side of dash, above kick panel.
Turn Signal Flasher Relay	On fuse block.

GMC Vandura G2500 1991 - CIRCUIT PROTECTION DEVICES

GMC Vandura G2500 1991 CIRCUIT PROTECTION DEVICES LOCATION

Component	Location
Circuit Breakers
Headlight/Parking Light	In headlight switch.
Power Door Lock	On fuse block.
Power Window	On fuse block.
Rear A/C	On firewall.
Fuse Block
4.3L VIN Z	Under left side of dash, above kick panel. See Fig. 3.
5.0L VIN H & 5.7L VIN K	Under left side of dash, above kick panel. See Fig. 4.
7.4L VIN N	Under left side of dash, above kick panel. See Fig. 2.
Fusible Links
A/C-Heater (Red)	At battery junction block (rear unit).
Alternator (Rust)	At battery junction block.
Auxiliary Cooling Fan Relay (Rust)	At battery junction block.
Glow Plug Controller (Rust)	At starter solenoid (diesel).
Ignition Switch (Rust)	At battery junction block (2 links).
Power Accessories (Rust)	At battery junction block.

GMC Vandura G2500 1991 - CONTROL UNITS

GMC Vandura G2500 1991 CONTROL UNITS LOCATION

Component	Location
ABS Control Module	On left side of engine compartment.
Audio Alarm Module	Behind dash, below fuse block.
Cruise Control Module	Behind instrument panel, near steering column.
Digital Ratio Adaptor Controller (DRAC)	On parking brake lever assembly.
Electronic Control Module (ECM)
4.3L VIN Z	Under driver's seat. See Fig. 3.
5.0L VIN H & 5.7L VIN K	Under driver's seat. See Fig. 4.
7.4L VIN N	Under driver's seat. See Fig. 2.
Elec. Spark Control (ESC) Module
4.3L VIN Z	Under driver's seat. See Fig. 3.
5.0L VIN H & 5.7L VIN K	Under driver's seat. See Fig. 4.
7.4L VIN N	Under driver's seat. See Fig. 2.
Glow Plug Controller (Diesel)
Controls & Relays	On left rear of intake manifold. See Fig. 5.
6.2L Diesel	On left rear of intake manifold. See Fig. 6.
Hot Fuel Module
5.0L VIN H & 5.7L VIN K	Under driver's seat. See Fig. 4.
7.4L VIN N	Under driver's seat. See Fig. 2.
Hydro-Boost Elec. Delay Module	Behind left side of instrument panel.
Light Driver Module (Diesel)	Under right side of dash.
Power Door Lock Delay Module	Behind dash, to right of steering column.
Pulse Wiper Control Module	Taped to harness, at left side of steering column.

GMC Vandura G2500 1991 - SENDING UNITS & SENSORS

GMC Vandura G2500 1991 SENDING UNITS & SENSORS LOCATION

Component	Location
Coolant Level Sensor	In radiator.
Coolant Temp. Sending Unit/Switch	On left cylinder head. See Fig. 6.
Coolant Temperature Sensor
6.2L Diesel	On intake manifold. See Fig. 6.
4.3L VIN Z	On intake manifold. See Fig. 3.
5.0L VIN H & 5.7L VIN K	On intake manifold. See Fig. 4.
7.4L VIN N	On intake manifold. See Fig. 2.
Engine Speed Sensor (Diesel)	On right rear of engine.
Fuel Pressure Sensor (Diesel)	On rear of intake manifold, in fuel filter assembly. See Fig. 6.
Knock Sensor
4.3L	On left side of engine, under exhaust manifold. See Fig. 3.
5.0L & 5.7L	On lower right side of engine block, above starter. See Fig. 4.
7.4L VIN N	On left side of engine block, above starter. See Fig. 2.
Low Coolant Sensor (Diesel)	On right side of radiator.
Manifold Abs. Press (MAP) Sensor
Diesel	On right side of firewall.
Gas
4.3L VIN Z	On bracket, at center of right valve cover. See Fig. 3.
5.0L VIN H & 5.8L VIN K	On bracket, at center of right valve cover. See Fig. 4.
7.4L VIN N	On bracket, at center of right valve cover. See Fig. 2.
Oil Pressure Sending Unit/Switch
Diesel	On engine block, behind left cylinder head. See Fig. 6.
Gas
4.3L VIN Z	On left side of engine block, above oil filter. See Fig. 3.
5.0L VIN H & 5.8L VIN K	On left side of engine block, above oil filter. See Fig. 4.
7.4L VIN N	On left side of engine block, above oil filter. See Fig. 2.
Throttle Position Sensor (TPS)
4.3L VIN Z	On throttle body (gas), or on injection pump (diesel). See Fig. 3.
5.0L VIN H & 5.8L VIN K
Gas	On throttle body See Fig. 4.
Diesel	On injection pump. See Fig. 4.
7.4L VIN N
Gas	On throttle body. See Fig. 2.
Diesel	On injection pump. See Fig. 2.
Vehicle Speed Sensor (VSS)
4.3L VIN Z	In speedometer cable adapter housing, in trans. tailshaft. See Fig. 3.
5.0L VIN H & 5.8L VIN K	In speedometer cable adapter housing, in trans. tailshaft. See Fig. 4.
7.4L VIN N	In speedometer cable adapter housing, in trans. tailshaft. See Fig. 2.
Water-In-Fuel Sensor (Diesel)	In fuel filter assembly. See Fig. 6.

GMC Vandura G2500 1991 - MOTORS

GMC Vandura G2500 1991 MOTORS LOCATION

Component	Location
A/C-Heater Blower Motor	On right side of firewall.
Idle Air Control (IAC) Motor
4.3L VIN Z	On throttle body (gas). See Fig. 3.
5.0L VIN H & 5.7L VIN K	On throttle body (gas). See Fig. 4.
7.4L VIN N	On throttle body (gas). See Fig. 2.
Power Door Lock Motor	At rear, in each door.
Power Window Motor	At center, in each door.
Windshield Washer Motor	On windshield washer reservoir.
Windshield Wiper Motor	On firewall.

GMC Vandura G2500 1991 - SOLENOIDS & SOLENOID VALVES

GMC Vandura G2500 1991 SOLENOIDS & SOLENOID VALVES LOCATION

Component	Location
Canister Purge Solenoid Valve	On vapor canister, or in vapor hose.
Cold Advance Solenoid (Diesel)	On injection pump.
Elec. Air Control (EAC) Solenoid	Behind air pump, on right rear of engine. See Fig. 3.
EGR Dump Solenoid (Diesel)	On top left rear of engine. See Fig. 5.
EGR/EPR Solenoids (Diesel)	On top left rear of engine. See Fig. 5.
EGR Vacuum Solenoid (Gas)
4.3L VIN Z	At right top of engine. See Fig. 3.
5.0L VIN H & 5.8L VIN K	At right top of engine. See Fig. 4.
7.4L VIN N	At right top of engine. See Fig. 2.
Fast Idle Solenoid (Diesel)	On injection pump.
Fuel Shutoff Solenoid (Diesel)	At top center of engine, near intake plenum.
Torque Conv. Clutch (TCC) Solenoid
5.0L VIN H & 5.8L VIN K	In automatic transmission. See Fig. 4.
7.4L VIN N	In automatic transmission. See Fig. 2.

GMC Vandura G2500 1991 - SWITCHES

GMC Vandura G2500 1991 SWITCHES LOCATION

Component	Location
A/C Coolant Temp. Cut-Out Switch	On thermostat housing.
A/C Press. Cycling Switch	On rear of accumulator.
Aux. Cooling Fan Switch (7.4L)	On right side of engine block, above starter.
Back-Up Light Switch (A/T)	At base of steering column.
Brake Pressure Warning Switch	On proportioning valve, at left frame rail.
Coolant Temperature Switch	In left cylinder head.
Fuel Pump/Oil Press. Switch
7.4L	On front of left cylinder head.
Except 7.4L	On rear of intake manifold.
Glow Plug Inhibit Switch (Diesel)	On front of engine.
Hydro-Boost Flow Switch	In pressure line, at power steering pump.
Hydro-Boost Press. Warning Switch	In pressure line, behind master cylinder.
Stoplight Switch	On brake pedal bracket.
Throttle Position Switch (Diesel)	On fuel injection pump.
Transmission Kickdown Switch	At top of accelerator pedal bracket.

GMC Vandura G2500 1991 - MISCELLANEOUS

GMC Vandura G2500 1991 MISCELLANEOUS LOCATION

Component	Location
A/C-Heater Blower Resistors	On evaporator case, in engine compartment.
ALDL Diagnostic Connector
4.3L VIN Z	Under left side of dash. See Fig. 3.
5.0L VIN H & 5.8L VIN K	Under left side of dash. See Fig. 4.
7.4L VIN N	Under left side of dash. See Fig. 2.
Fuel Heater (Diesel)	At fuel filter. See Fig. 6.
Fuel Pump Prime/Test Connector
4.3L VIN Z	On firewall, next to fuel pump relay. See Fig. 3.
5.0L VIN H & 5.8L VIN K	On firewall, next to fuel pump relay. See Fig. 4.
7.4L VIN N	On firewall, next to fuel pump relay. See Fig. 2.
Hydro-Boost In-Line Diode	In harness, behind instrument panel.
Set Timing Connector (Gas)	In harness, near distributor.
Tachometer Connector	In harness, at ignition coil.
Vehicle Speed Sensor (VSS) Buffer	Taped to harness, behind instrument panel.