Chevrolet Pickup C2500 1990 - ELECTRICAL COMPONENT LOCATOR 1989-90 ELECTRICAL COMPONENT LOCATIONS General Motors Corp. - Electrical Components

Chevrolet Pickup C2500 1990 - BUZZERS, RELAYS & TIMERS

Chevrolet Pickup C2500 1990 BUZZERS, RELAYS & TIMERS LOCATION

Component	Location
A/C Clutch Relay	On top of plenum, behind right side of dash.
A/C-Heater Blower Relays	On top of plenum, behind right side of dash.
Auxiliary Cooling Fan Relay	On left front inner fender panel, near firewall.
Downshift Relay (THM 400/3L80)
5.7L	On right side of firewall, behind battery junction block cover. See Fig. 1 .
7.4L - 1989	On right side of firewall, behind battery junction block cover. See Fig. 2 .
7.4L - 1990	On right side of firewall, behind battery junction block cover. See Fig. 3 .
Right Side Of Firewall View	On right side of firewall, behind battery junction block cover. See Fig. 4 .
Auxiliary Battery Relay	On left front inner fender panel, above wheelwell.
Cold Advance Control Relay (6.2L)	On right side of firewall, behind battery junction block cover. See Fig. 4 .
Foglight Relay	Behind dash, above convenience center, next to hazard flasher. See Fig. 5 .
Fuel Pump Relay
4.3L Engine	On right side of firewall, behind battery junction block cover. See Fig. 6 .
5.7L	On right side of firewall, behind battery junction block cover. See Fig. 1 .
7.4L - 1989	On right side of firewall, behind battery junction block cover. See Fig. 2 .
7.4L - 1990	On right side of firewall, behind battery junction block cover. See Fig. 3 .
Right Side Of Firewall View	On right side of firewall, behind battery junction block cover. See Fig. 4 .
Glow Plug Controller Relay	On top of engine, above right valve cover.
Hazard Flasher Relay	Under left side of dash, near convenience center.
Headlight Relay	Behind left side of dash, above convenience center. See Fig. 5 .
Horn Relay	On convenience center, below left side of dash. See Fig. 5 .
Transfer Case Relay	On right side of firewall, behind battery junction block cover. See Fig. 4 .
Turn Signal Flasher Relay	On convenience center.

Chevrolet Pickup C2500 1990 - CIRCUIT PROTECTION DEVICES

Chevrolet Pickup C2500 1990 CIRCUIT PROTECTION DEVICES LOCATION

Component	Location
Circuit Breakers
Accessory/Battery	On fuse block.
Accessory/Ignition	On fuse block.
Fuel Pump In-Line Fuse	On right side of firewall, behind battery junction block cover. See Fig. 4 .
Fuse Block
4.3L	Under left side of dash, near kick panel. See Fig. 6 .
5.7L	Under left side of dash, near kick panel. See Fig. 1 .
7.4L - 1989	Under left side of dash, near kick panel. See Fig. 2 .
7.4L - 1990	Under left side of dash, near kick panel. See Fig. 3 .
Fusible Links
Air Conditioning (Rust)	On right side of firewall, at battery junction block. See Fig. 4 .
A/T Kickdown Sol. (Red)	On right side of firewall, at battery junction block. See Fig. 4 .
Aux. Battery Relay (Rust)	On right side of firewall, at battery junction block. See Fig. 4 .
Aux. Cooling Fan Relay (Gray)	On right side of firewall, at battery junction block. See Fig. 4 .
Charging System (Blue)	On right side of firewall, at battery junction block. See Fig. 4 .
Diesel ECM (Gray)	On right side of firewall, at battery junction block. See Fig. 4 .
ECM (Gray)	On right side of firewall, at battery junction block. See Fig. 4 .
Fuse Block (Black)	On right side of firewall, at battery junction block. See Fig. 4 .
Glow Plug Controller (Blue)	On right side of firewall, at battery junction block. See Fig. 4 .
Instrument Panel (Black)	On right side of firewall, at battery junction block. See Fig. 4 .
Junction Block (Diesel) (Blue)	On positive battery cable, below battery.
Junction Block (Gas) (Red)	On positive battery cable, below battery.

Chevrolet Pickup C2500 1990 - CONTROL UNITS

Chevrolet Pickup C2500 1990 CONTROL UNITS LOCATION

Component	Location
Check Engine Light Driver Module (Diesel Only)	Under right side of dash, above blower motor. See Fig. 7 .
Cruise Control Module	On left side of firewall, near brake booster. See Fig. 8 .
Electronic Control Module (ECM)
4.3L	Behind right side of dash, above blower motor. See Fig. 6 .
5.7L	Behind right side of dash, above blower motor. See Fig. 1 .
7.4L - 1989	Behind right side of dash, above blower motor. See Fig. 2 .
7.4L - 1990	Behind right side of dash, above blower motor. See Fig. 3 .
Right Side Of Dash	Behind right side of dash, above blower motor. See Fig. 7 .
Electronic Spark Control (ESC)
4.3L	On right side of engine, above valve cover. See Fig. 6 .
5.7L	On right side of engine, above valve cover. See Fig. 1 .
4.3L Component View	On right side of engine, above valve cover. See Fig. 9 .
5.0L & 5.7L Component View	On right side of engine, above valve cover. See Fig. 10 .
Diesel Electronic Control Module (DECM)	Behind right side of dash, above blower motor. See Fig. 7 .
Hot Fuel Handling Module (5.7L H/D)	Behind right side of Instrument Panel above Blower Motor. See Fig. 1 .
Glow Plug Controller (6.2L)	On left rear of intake manifold.
Low Coolant Module (6.2L)	On center of firewall.
Rear Anti-Lock Brake Module	On bracket, left of master cylinder. See Fig. 8 .

Chevrolet Pickup C2500 1990 - SENDING UNITS & SENSORS

Chevrolet Pickup C2500 1990 SENDING UNITS & SENSORS LOCATION

Component	Location
Cold Advance Control (CAC) & Fast Idle Solenoid Temp. Sensor (6.2L)	On rear of right cylinder head.
Coolant Temperature Sensor
4.3L	In front of intake manifold, at thermostat housing. See Fig. 6 .
5.0L & 5.7L	On right front of engine, in front of valve cover. See Fig. 1 .
6.2L	On right front of intake manifold.
7.4L - 1989	On right front of intake manifold, near thermostat housing. See Fig. 2 .
7.4L - 1990	On right front of intake manifold, near thermostat housing. See Fig. 3 .
Coolant Temp. Sending Unit/Switch	In left cylinder head.
Engine Speed Sensor (6.2L)	On rear of intake manifold.
Knock Sensor
4.3L	On lower left side of engine, under exhaust manifold.
4.3L	On lower right side of engine, under exhaust manifold. See Fig. 6 .
5.7L	On lower right side of engine, under exhaust manifold. See Fig. 1 .
5.0L & 5.7L Component View	On lower right side of engine, under exhaust manifold. See Fig. 10 .
Manifold Absolute Pressure (MAP) Sensor
Diesel	On left side of firewall, near wiper motor.
Gas
4.3L	On right side of engine, above valve cover. See Fig. 6 .
5.7L	On right side of engine, above valve cover. See Fig. 1 .
7.4L - 1989	On right side of engine, above valve cover. See Fig. 2 .
7.4L - 1990	On right side of engine, above valve cover. See Fig. 3 .
4.3L Component View	On right side of engine, above valve cover. See Fig. 9 .
5.0 & 5.7L Component View	On right side of engine, above valve cover. See Fig. 10 .
7.4L Component View	On right side of engine, above valve cover. See Fig. 11 .
Oil Pressure Sending Unit/Switch
Diesel	On left rear of engine.
Gas
4.3L	On left side of engine, under exhaust manifold. See Fig. 6 .
5.7L	On left side of engine, under exhaust manifold. See Fig. 1 .
7.4L - 1989	On left side of engine, under exhaust manifold. See Fig. 2 .
7.4L - 1990	On left side of engine, under exhaust manifold. See Fig. 3 .
Oxygen (O2) Sensor
4.3L	In exhaust manifold or header pipe. See Fig. 6 .
5.7L	In exhaust manifold or header pipe. See Fig. 1 .
7.4L - 1989	In exhaust manifold or header pipe. See Fig. 2 .
7.4L - 1990	In exhaust manifold or header pipe. See Fig. 3 .
Throttle Position Sensor (TPS)
Diesel	On injection pump throttle valve.
Gasoline
4.3L	On throttle body. See Fig. 6 .
5.7L	On throttle body. See Fig. 1 .
7.4L - 1989	On throttle body. See Fig. 2 .
7.4L - 1990	On throttle body. See Fig. 3 .
4.3L Component View	On throttle body. See Fig. 9 .
5.0L & 5.7L Component View	On throttle body. See Fig. 10 .
7.4L Component View	On throttle body. See Fig. 11 .
Vehicle Speed Sensor (VSS)
4.3L (2WD)	On right side of extension housing. See Fig. 6 .
4.3L (4WD)	On right side of transfer case. See Fig. 6 .
5.7L (2WD)	On right side of extension housing. See Fig. 1 .
5.7L (4WD)	On right side of transfer case. See Fig. 1 .
7.4L - 1989 (2WD)	On right side of extension housing. See Fig. 2 .
7.4L - 1989 (4WD)	On right side of transfer case. See Fig. 2 .
7.4L - 1990 (2WD)	On right side of extension housing. See Fig. 3 .
7.4L - 1990 (4WD)	On right side of transfer case. See Fig. 3 .

Chevrolet Pickup C2500 1990 - MOTORS

Chevrolet Pickup C2500 1990 MOTORS LOCATION

Component	Location
A/C-Heater Blower Motor	Behind right side of dash. See Fig. 7 .
A/C-Heater Door Motor	On plenum, behind right side of dash.
Windshield Wiper Motor	In plenum, on left center of firewall.

Chevrolet Pickup C2500 1990 - SOLENOIDS & SOLENOID VALVES

Chevrolet Pickup C2500 1990 SOLENOIDS & SOLENOID VALVES LOCATION

Component	Location
A/T Downshift Solenoid	On left side of transmission, in front of vehicle speed sensor.
Cold Advance Solenoid (6.2L)	On injection pump, on left front of engine.
EGR Pulse Solenoid Valve (6.2L)	On top of engine, near left valve cover.
EGR Vacuum Solenoid
4.3L	On right side of engine, above valve cover. See Fig. 6 .
5.7L	On right side of engine, above valve cover. See Fig. 1 .
5.0 & 5.7L Component View	On right side of engine, above valve cover. See Fig. 10 .
6.2L	On top left of engine, near left valve cover.
7.4L - 1989	On top of engine, on left valve cover. See Fig. 2 .
7.4L - 1990	On top of engine, on left valve cover. See Fig. 3 .
Elec. Air Control (EAC) Solenoid
4.3L	On right front of engine, near air pump. See Fig. 6 .
5.7L	On right front of engine, near air pump. See Fig. 1 .
7.4L - 1989	On right front of engine, near air pump. See Fig. 2 .
7.4L - 1990	On right front of engine, near air pump. See Fig. 3 .
4.3L Component View	On right front of engine, near air pump. See Fig. 9 .
5.0 & 5.7L Component View	On right front of engine, near air pump. See Fig. 10 .
7.4L Component View	On right front of engine, near air pump. See Fig. 11 .
Exhaust Pressure Regulator (EPR) Solenoid Valve (6.2L)	On top left rear of engine.
Fast Idle Solenoid (6.2L)	On injection pump, on left front of engine.
Front Axle Solenoid	On right side of differential case.
Fuel Shutoff Solenoid (6.2L)	On injection pump, on left front of engine.
Idle Air Control (IAC) Valve
4.3L	On right side of throttle body. See Fig. 6 .
5.7L	On right side of throttle body. See Fig. 1 .
7.4L - 1989	On right side of throttle body. See Fig. 2 .
7.4L - 1990	On right side of throttle body. See Fig. 3 .
4.3L Component View	On right side of throttle body. See Fig. 9 .
5.0L & 5.7L Component View	On right side of throttle body. See Fig. 10 .
7.4L Component View	On right side of throttle body. See Fig. 11 .
Rear Anti-Lock Brake Valve	Below master cylinder. See Fig. 8 .
Torque Conv. Clutch (TCC) Solenoid
4.3L	In automatic transmission. See Fig. 6 .
5.7L	In automatic transmission. See Fig. 1 .

Chevrolet Pickup C2500 1990 - SWITCHES

Chevrolet Pickup C2500 1990 SWITCHES LOCATION

Component	Location
A/C Air Inlet Press. Switch
5.0L & 5.7L Component View	On rear of A/C compressor. See Fig. 10 .
7.4L Component View	On rear of A/C compressor. See Fig. 11 .
A/C Pressure Cycling Switch
4.3L Component View	On accumulator. See Fig. 9 .
5.0 & 5.7L Component View	On accumulator. See Fig. 10 .
7.4L Component View	On accumulator. See Fig. 11 .
Back-Up Light Switch (M/T)	On left side of transmission.
Brake Pressure (Warning) Switch	In hydraulic brake combination valve.
Brake/Stoplight Switch	On brake pedal bracket.
Clutch/Neutral Safety Switch	On clutch pedal bracket.
Cooling Fan Temp. Switch (7.4L)	In right cylinder head, above exhaust manifold. See Fig. 11 .
Cruise Control Release Switch	On brake pedal bracket.
Front Axle Switch	Near differential case, at front of engine.
Fuel Pump/Oil Pressure Switch
4.3L	On left rear of engine, near distributor. See Fig. 6 .
5.0L & 5.7L	On left rear of engine block. See Fig. 1 .
7.4L - 1989	On left side of engine block, under exhaust manifold. See Fig. 2 .
7.4L - 1990	On left side of engine block, under exhaust manifold. See Fig. 3 .
Headlight Dimmer Switch	On left side of steering column, behind dash.
Inhibit Switch	On right side of firewall, near accumulator.
Low Coolant Switch	In top of radiator.
Parking Brake Switch	On parking brake pedal bracket.
Park/Neutral Switch	On steering column, under dash
TCC Brake Switch	On brake pedal bracket.
TCC Governor Pressure Switch	In automatic transmission.
Transfer Case Switch	On left front of transfer case.

Chevrolet Pickup C2500 1990 - MISCELLANEOUS

Chevrolet Pickup C2500 1990 MISCELLANEOUS LOCATION

Component	Location
A/C Compressor Clutch Diode	In A/C compressor clutch connector.
A/C-Heater Blower Resistor	On evaporator case, in engine compartment.
ALDL Diagnostic Connector
4.3L	Under left side of dash, to left of column. See Fig. 6 .
5.7L	Under left side of dash, to left of column. See Fig. 1 .
7.4L - 1989	Under left side of dash, to left of column. See Fig. 2 .
7.4L - 1990	Under left side of dash, to left of column. See Fig. 3 .
Battery Junction Block	On right side of firewall, behind cover. See Fig. 4 .
Convenience Center	Under left side of dash, left of steering column. See Fig. 5 .
Front Axle Actuator	Below front of right exhaust manifold.
Fuel Heater/Water Detector (6.2L)	On top right side of engine.
Fuel Pump (Gas)	In fuel tank.
Fuel Pump (Diesel)	On left frame rail.
Fuel Pump Prime/Test Connector
4.3L	On right side of firewall, near battery junction block. See Fig. 6 .
5.7L	On right side of firewall, near battery junction block. See Fig. 1 .
7.4L - 1989	On right side of firewall, near battery junction block. See Fig. 2 .
7.4L - 1990	On right side of firewall, near battery junction block. See Fig. 3 .
Rear Anti-Lock Brake In-Line Diode	Under left side of dash, near convenience center.
TCC In-Line Resistor	Under right side of dash, under blower motor. See Fig. 7 .