GMC Forward Control P3500 (1985-1999) org/ Wiring diagrams

1-2 SHIFT SOL 1-2 SHIFT SOLENOID 2-3 SHIFT SOL 2-3 SHIFT SOLENOID 4.3L (VIN W), 5.7L (VIN R) A/C COMPRESSOR RELAY, GENERATOR, SEAT BELT/ HEADLAMPS ALARM MODULE A/T FLUID PRESSURE MANUAL VALVE POSITION SWITCH A/T ISS HI IN A/T ISS LO IN ANTI-LOCK BRAKES, CRUISE CONTROL, SHIFT INTERLOCK SYSTEMS AUTOMATIC TRANSMISSION BATTERY IN BLK WIRE BLK/WHT WIRE BLU/WHT WIRE BRAKE SWITCH INPUT BRN WIRE BRN/WHT WIRE DATA CLASS II DK BLU WIRE ECM 1 FUSE 12 ECM-BAT FUSE 6 ECT SENS INPUT ELECTRONIC BRAKE CONTROL MODULE, CRUISE CONTROL MODULE ENGINE CONTROLS SYSTEM FUEL INJECTORS (ENGINE CONTROLS SYSTEM) FUEL PUMP RELAY, SWITCH GAUGES FUSE 8 GRY WIRE HOT AT ALL TIMES HOT IN RUN HOT IN RUN OR START I-3 FUSE 9 I/P FUSE BLOCK IGNITION IN INSTRUMENT CLUSTER LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE MIL CONTROL ORG/ WIRE PCM GROUND PCS SOL HI OUT PCS SOL LO OUT PNK WIRE PPL PPL DATA LINK CONNECTOR (PARTIAL) (BELOW DASH NEAR STEERING COLUMN) PPL/WHT WIRE PRESS CTRL SOLENOID RANGE SIGNAL "A" RANGE SIGNAL "B" RANGE SIGNAL "C" RED WIRE RED/BLK WIRE SENSOR GROUND SENSOR RETURN SERVICE ENGINE SOON INDICATOR TCC PWM SOL TCC PWM SOLENOID TCC/ STOP LAMPS SWITCH THROTTLE POSITION SENSOR (ON THROTTLE BODY) TP SENS INPUT TRANS FLUID TEMP SENSOR TRANS FUSE 17 TRANS TEMP SIG IN VEHICLE CONTROL MODULE (CENTER FRONT OF ENGINE COMPT) VEHICLE SPEED SENSOR (LEFT REAR OF TRANSMISSION) VSS HI VSS LO YEL WIRE YEL/BLK WIRE

1-2 SHIFT SOL 1-2 SHIFT SOLENOID 2-3 SHIFT SOL 2-3 SHIFT SOLENOID 4.3L (VIN W), 5.7L (VIN R) A/C COMPRESSOR RELAY, GENERATOR, SEAT BELT/ HEADLAMPS ALARM MODULE A/T FLUID PRESSURE MANUAL VALVE POSITION SWITCH A/T ISS HI IN A/T ISS LO IN ANTI-LOCK BRAKES, CRUISE CONTROL, SHIFT INTERLOCK SYSTEMS AUTOMATIC TRANSMISSION BATTERY IN BLK WIRE BLK/WHT WIRE BLU/WHT WIRE BRAKE SWITCH INPUT BRN WIRE BRN/WHT WIRE DATA CLASS II DK BLU WIRE ECM 1 FUSE 12 ECM-BAT FUSE 6 ECT SENS INPUT ELECTRONIC BRAKE CONTROL MODULE, CRUISE CONTROL MODULE ENGINE CONTROLS SYSTEM FUEL INJECTORS (ENGINE CONTROLS SYSTEM) FUEL PUMP RELAY, SWITCH GAUGES FUSE 8 GRY WIRE HOT AT ALL TIMES HOT IN RUN HOT IN RUN OR START I-3 FUSE 9 I/P FUSE BLOCK IGNITION IN INSTRUMENT CLUSTER LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE MIL CONTROL ORG/ WIRE PCM GROUND PCS SOL HI OUT PCS SOL LO OUT PNK WIRE PPL PPL DATA LINK CONNECTOR (PARTIAL) (BELOW DASH NEAR STEERING COLUMN) PPL/WHT WIRE PRESS CTRL SOLENOID RANGE SIGNAL "A" RANGE SIGNAL "B" RANGE SIGNAL "C" RED WIRE RED/BLK WIRE SENSOR GROUND SENSOR RETURN SERVICE ENGINE SOON INDICATOR TCC PWM SOL TCC PWM SOLENOID TCC/ STOP LAMPS SWITCH THROTTLE POSITION SENSOR (ON THROTTLE BODY) TP SENS INPUT TRANS FLUID TEMP SENSOR TRANS FUSE 17 TRANS TEMP SIG IN VEHICLE CONTROL MODULE (CENTER FRONT OF ENGINE COMPT) VEHICLE SPEED SENSOR (LEFT REAR OF TRANSMISSION) VSS HI VSS LO YEL WIRE YEL/BLK WIRE

1-2 SHIFT SOL 1-2 SHIFT SOLENOID 2-3 SHIFT SOL 2-3 SHIFT SOLENOID 3-2 SHIFT SOL 3-2 SHIFT SOLENOID A/C COMPRESSOR RELAY GENERATOR A/T FLUID PRESSURE MANUAL VALVE POSITION SWITCH A/T INPUT SPEED SENSOR (LEFT SIDE OF TRANSMISSION) A/T ISS SENS HI IN A/T ISS SENS LO IN A/T OUTPUT SPEED SENSOR (LEFT SIDE OF TRANSMISSION) ACCELERATOR PEDAL POSITION MODULE (ATTACHED TO ACCELERATOR PEDAL) APP 1 SIGNAL IN APP 2 SIGNAL IN APP 3 SIGNAL IN AUTOMATIC TRANSMISSION BATTERY IN BLK WIRE BLK/WHT WIRE BLU/WHT WIRE BRAKE SWITCH IN BRN WIRE BRN/WHT WIRE CLASS II DATA DATA LINK CONNECTOR (PARTIAL) (BELOW DASH, NEAR STEERING COLUMN) DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE ECM 1 FUSE 12 ECM-BAT FUSE 6 ECT SENSOR IN ELECTRONIC BRAKE CONTROL MODULE ENGINE COOLANT TEMPERATURE SENSOR (TOP FRONT OF ENGINE) FUEL PUMP RELAY, ENGINE OIL PRESSURE INDICATOR SENSOR GAUGES FUSE 8 GRY WIRE HOT AT ALL TIMES HOT IN RUN HOT IN RUN OR START I-3 FUSE 9 I/P FUSE BLOCK IGNITION IN INSTRUMENT CLUSTER LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE MIL CONTROL ORG/ WIRE OSS HI IN OSS LO IN OSS OUT PCM GROUND PCS SOL HI OUT PCS SOL LO OUT PNK WIRE POWERTRAIN CONTROL MODULE (LEFT SIDE OF DRIVER'S ISLAND) PPL PPL PPL PPL/WHT WIRE PRESS CTRL HI SOLENOID RED WIRE RED/BLK WIRE SENSOR GROUND SERVICE ENGINE SOON INDICATOR STOP-HAZ FUSE 11 STOPLAMP SWITCH IN TAN WIRE TFT SENSOR IN TORQUE CONVERTER CLUTCH, STOPLAMP SWITCH TRANS FLUID TEMP SENSOR TRANS RANGE "A" TRANS RANGE "B" TRANS RANGE "C" TRANSMISSION FUSE 17 VEHICLE SPEED SENSOR BUFFER VEHICLE SPEED SENSOR CALIBRATOR (LEFT SIDE OF DRIVER'S ISLAND) VSS LO IN VSS OUT WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

2-3 SHIFT SOL CTRL 1-2 SHIFT SOL CTRL DIAGNOSTIC TEST 9 6 DATA LINK CONNECTOR (PARTIAL) (BELOW DASH, NEAR STEERING COLUMN) A/T INPUT SHAFT SPEED SENSOR (LEFT SIDE OF TRANSMISSION) A/T OUTPUT SHAFT SPEED SENSOR (LEFT SIDE OF TRANSMISSION) AUTOMATIC TRANSMISSION BAROMETRIC PRESSURE SENSOR (TOP LEFT REAR OF INTAKE MANIFOLD) BATTERY FEED BLK WIRE BLK/WHT WIRE BLU/WHT WIRE BRAKE SIGNAL TCC PWM CONTROL BRN WIRE DK BLU WIRE DRL MODULE, DRL RELAY, GENERATOR ECM 1 FUSE 12 ECM-BAT FUSE 6 ELECTRONIC BRAKE CONTROL MODULE ENGINE OIL PRESSURE INDICATOR SENSOR, FUEL PUMP RELAY ENGINE SPEED SENSOR (REAR OF INTAKE MANIFOLD) ENGINE SPEED SIGNAL SENSOR GROUND TP SENSOR INPUT FUEL INJECTION PUMP SHUTOFF SOLENOID,, FUEL PUMP RELAY GAUGES FUSE 8 GRY WIRE GRY/BLK WIRE HOT AT ALL TIMES HOT IN HOT IN RUN OR START I-3 FUSE 9 I/P FUSE BLOCK IGN BUSS INSTRUMENT CLUSTER LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE ORG/ WIRE OSS INPUTS OUT PCS HI PCS LO IGNITION PNK WIRE PPL PPL/WHT WIRE PRESSURE CONTROL SOLENOID RANGE MODE SELECTOR RANGE SIGNAL A RANGE SIGNAL B RANGE SIGNAL C RED WIRE RED/BLK WIRE RUN WIRE SERVICE TRANS IND SERIAL DATA SERVICE TRANSMISSION INDICATOR SYSTEM GROUND SYSTEM GROUND SENSOR GROUND 5 VOLTS REF TAN WIRE TCC PWM SOL 1-2 SHIFT SOL 2-3 SHIFT SOL THROTTLE POSITION SENSOR (RIGHT SIDE OF FUEL INJECTION PUMP) TORQUE CONVERTER CLUTCH, STOPLAMP SWITCH TRANS FLUID TEMP SIG BARO SENSOR INPUT TRANS FUSE 17 TRANSMISSION CONTROL MODULE (LEFT SIDE OF DRIVER'S ISLAND) TRANSMISSION TEMPERATURE SENSOR VEHICLE SPEED INPUT INPUT SPEED SENS LO INPUT SPEED SENS HI VEHICLE SPEED SENSOR CALIBRATOR VEHICLE SPD OUTPUT WHT WIRE WHT/BLK WIRE YEL/BLK WIRE

1-2 SHIFT SOL 1-2 SHIFT SOLENOID 2-3 SHIFT SOL 2-3 SHIFT SOLENOID 4.3L (VIN W), 5.7L (VIN R) A/C COMPRESSOR RELAY, GENERATOR, SEAT BELT/ HEADLAMPS ALARM MODULE A/T FLUID PRESSURE MANUAL VALVE POSITION SWITCH A/T ISS HI IN A/T ISS LO IN ANTI-LOCK BRAKES, CRUISE CONTROL, SHIFT INTERLOCK SYSTEMS AUTOMATIC TRANSMISSION BATTERY IN BLK WIRE BLK/WHT WIRE BLU/WHT WIRE BRAKE SWITCH INPUT BRN WIRE BRN/WHT WIRE DATA CLASS II DK BLU WIRE ECM 1 FUSE 12 ECM-BAT FUSE 6 ECT SENS INPUT ELECTRONIC BRAKE CONTROL MODULE, CRUISE CONTROL MODULE ENGINE CONTROLS SYSTEM FUEL INJECTORS (ENGINE CONTROLS SYSTEM) FUEL PUMP RELAY, SWITCH GAUGES FUSE 8 GRY WIRE HOT AT ALL TIMES HOT IN RUN HOT IN RUN OR START I-3 FUSE 9 I/P FUSE BLOCK IGNITION IN INSTRUMENT CLUSTER LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE MIL CONTROL ORG/ WIRE PCM GROUND PCS SOL HI OUT PCS SOL LO OUT PNK WIRE PPL PPL DATA LINK CONNECTOR (PARTIAL) (BELOW DASH NEAR STEERING COLUMN) PPL/WHT WIRE PRESS CTRL SOLENOID RANGE SIGNAL "A" RANGE SIGNAL "B" RANGE SIGNAL "C" RED WIRE RED/BLK WIRE SENSOR GROUND SENSOR RETURN SERVICE ENGINE SOON INDICATOR TCC PWM SOL TCC PWM SOLENOID TCC/ STOP LAMPS SWITCH THROTTLE POSITION SENSOR (ON THROTTLE BODY) TP SENS INPUT TRANS FLUID TEMP SENSOR TRANS FUSE 17 TRANS TEMP SIG IN VEHICLE CONTROL MODULE (CENTER FRONT OF ENGINE COMPT) VEHICLE SPEED SENSOR (LEFT REAR OF TRANSMISSION) VSS HI VSS LO YEL WIRE YEL/BLK WIRE

A/C COMPRESSOR HIGH PRESSURE CUT-OFF SWITCH (ON REAR OF A/C COMPRESSOR) BLK WIRE BREAKOUT FOR CRUISE CONTROL MODULE, TOWARD RELAYS) BRN WIRE BRN/WHT WIRE DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE ENG BAT FUSE 10 ENGINE COOLANT TEMPERATURE SENSOR (ON TOP FRONT OF ENGINE) FUEL GAUGE FUEL PUMP MODULE (ON TOP OF FUEL TANK) GAUGES FUSE 8 GRY WIRE HOT AT ALL TIMES HOT IN RUN AND START I/P FUSE BLOCK IN PCM BREAKOUT, 20 CM FROM MAIN HARNESS TOWARD FUEL PUMP RELAY) INSTRUMENT CLUSTER LT BLU/WHT WIRE LT GRN WIRE MALFUNCTION INDICATOR LAMP (MIL) "SERVICE ENGINE SOON" MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR (TOP CENTER FRONT OF ENGINE) MASS AIR FLOW SENSOR (RIGHT FRONT OF ENGINE COMP, ON AIR INTAKE ASSEMBLY) NCA WIRE ORG/ WIRE PNK 16 17 18 19 20 21 WIRE PNK 22 23 WIRE PNK PNK 2 3 WIRE PNK PNK WIRE PNK WIRE PPL PPL PNK 9 10 11 12 13 14 15 WIRE RED WIRE RED/BLK WIRE SPEED METER TACH THROTTLE POSITION SENSOR (ON THROTTLE BODY, TOP OF ENGINE) TRANS FUSE 17 WHT WIRE YEL WIRE

1 2 3 4 5 6 7 8 PNK PNK WIRE A/C COMP CYL SW A/C REQUEST SIGNAL AIR CONDITIONING SYSTEM AUX ELECT COOLING FAN BRAKE SIGNAL SERIAL DATA PPL PPL B(+) BATTERY FEED RANGE SIGNAL B RANGE SIGNAL A BLK RED/ WIRE BLK WIRE BLK/WHT WIRE BLU/WHT WIRE BRN WIRE BRN/WHT WIRE COOLING FANS SYSTEM CRUISE CONTROL MODULE (ON RADIATOR SUPPORT BRACKET) CRUISE CTRL ENGAGED CRUISE ENGAGED SIG CTRL EST CYLINDER 1 CYLINDER 4 CYLINDER 5 CYLINDER 3 CYLINDER 6 CYLINDER 7 CYLINDER 2 CYLINDER 8 DISTRIBUTOR DK BLU WIRE DK GRN WIRE DK GRN/ WHT WIRE DK GRN/WHT WIRE ECM B FUSE 6 EGR VALVE FEED EGR VLV CTRL FUEL PMP RLY CTRL 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 FUEL PUMP PRIME CONNECTOR (TAPED TO FUEL PUMP RELAY BREAKOUT) GRN WIRE GROUND GRY WIRE HIGH VOLTAGE COIL WIRE HOT AT ALL TIMES HOT IN RUN I-3 FUSE 9 I/P FUSE BLOCK IGN FEED IGNITION COIL (ON BRACKET AT REAR OF INTAKE PLENUM) IGNITION CONTROL MODULE (ON BRACKET AT REAR OF INTAKE PLENUM) LT BLU/BLK WIRE LT BLU/WHT WIRE ORG/ WIRE PCS HIGH INPUT SPEED SENS LOW INPUT SPEED SENS HIGH IC CNTRL PCS LOW VCM GROUND VCM GROUND SENS GROUND PNK 16 17 18 19 20 21 WIRE PNK 22 23 WIRE PNK IGN FEED WIRE PNK WIRE PPL PPL ANTI-LOCK BRAKES SYSTEM PPL PPL DATA LINK CONNECTOR (DLC) (BELOW DASH, NEAR STEERING COLUMN) 4 5 PPL FUEL LEVEL MODULE A/C REC PPL TCC/STOPLAMP INPUT RANGE SIGNAL "C" RED WIRE RED/BLK WIRE SENSOR GROUND SIGNAL TIMING CTRL ELEC SPK SPARK PLUGS SPEED SENSOR INPUT TCC STOPLAMP SWITCH (OPENS W/BRAKE DEPRESSED) (AT BRAKE PEDAL SUPPORT) VSS OUTPUT SIGNAL VSS OUTPUT SIGNAL CHECK ENGINE LP CTRL WHT WIRE WHT/ BLU WIRE WHT/BLK WIRE