GMC Forward Control P3500 (1985-1999) yel Wiring diagrams

BACKUP LAMPS CIRCUIT BLK WIRE BLK/WHT WIRE BRN WIRE DK BLU WIRE DK GRN WIRE ENGINE CONTROLS SYSTEM (W/ DIESEL) GRN WIRE HAZARD HAZARD LAMPS FLASHER (ON INNER LEFT SIDE OF STEERING COLUMN SUPPORT BRACKET) HEAD OFF HEADLAMPS SWITCH HOT AT ALL TIMES HOT IN I/P FUSE BLOCK INSTRUMENT CLUSTER RIGHT TURN IND. INTERIOR LAMPS SYSTEM LEFT FRONT PARK/ TURN SIGNAL LAMP LEFT FRONT SIDE MARKER LAMP LEFT LICENSE LAMPS RIGHT LICENSE LAMPS LEFT REAR SIDE MARKER LAMP LEFT TURN IND LT BLU WIRE NCA WIRE NORMAL ORG/ WIRE PARK PPL PROVISION FOR CENTER HIGH MOUNTED STOP LAMP PROVISIONS FOR MARKER LAMPS (NEAR I/P FUSE BLOCK) RIGHT FRONT PARK/ TURN SIGNAL LAMP RIGHT REAR SIDE MARKER LAMP RIGHT TAIL/STOP, TURN SIGNAL LAMPS RUN WIRE STOP STOP-HAZ FUSE 11 TAIL TAIL LAMPS FUSE 7 TAIL STOP TAIL/STOP, TURN SIGNAL LAMPS TORQUE CONVERTER CLUTCH, STOP LAMPS SWITCH (AT BASE OF BRAKE PEDAL SUPPORT) TURN TURN B/U FUSE 5 TURN LEFT TURN RIGHT TURN SIGNAL FLASHER TURN SIGNAL SWITCH WHT WIRE YEL WIRE

7.4L BACK-UP LAMPS CIRCUIT BLK WIRE BLK/WHT WIRE BLU WIRE BRN WIRE CRUISE CONTROL SYSTEM DK BLU WIRE DK GRN WIRE ENGINE CONTROLS SYSTEM GRN WIRE HAZARD HAZARD LAMPS FLASHER (INNER LEFT SIDE OF STEERING COLUMN SUPPORT BRACKET) HEAD OFF HEADLAMPS SWITCH HOT AT ALL TIMES HOT IN I/P FUSE BLOCK INSTRUMENT CLUSTER RIGHT TURN INDIC INTERIOR LAMPS SYSTEM LEFT FRONT PARK/ TURN SIGNAL LAMP LEFT FRONT SIDE MARKER LAMP LEFT REAR SIDE MARKER LAMP LEFT TAIL/ STOP/ TURN SIGNAL LAMP LEFT TURN INDIC LT BLU WIRE NCA WIRE NORMAL ORG/ WIRE PARK PARK TURN PPL PROVISION FOR CENTER HIGH MOUNTED STOP LAMP PROVISIONS FOR MARKER LAMPS RIGHT FRONT PARK/ TURN SIGNAL LAMP RIGHT FRONT SIDE MARKER LAMP RIGHT REAR SIDE MARKER LAMP RIGHT LICENSE LAMP LEFT LICENSE LAMP RIGHT TAIL/ STOP/ TURN SIGNAL LAMP RUN WIRE STOP-HAZ FUSE 11 TAIL LPS FUSE 7 TORQUE CONVERTER CLUTCH, STOP LAMPS SWITCH (BRAKE PEDAL SUPPORT BRACKET) TURN TURN B/U FUSE 5 TURN LEFT TURN RIGHT TURN SIGNAL FLASHER TURN SIGNAL SWITCH WHT WIRE YEL WIRE

1996 VFTC ACCY BLK WIRE BLK/WHT WIRE BULB TEST DAYTIME RUNNING LAMPS (DRL) MODULE (ATTACHED TO I/P HARNESS AT STEERING COLUMN) DAYTIME RUNNING LAMPS (DRL) RELAY (ON MAIN SUPPORT BRACKET AT DRIVER'S ISLAND) DAYTIME RUNNING LAMPS (DRL) RELAY 2 DIODE NETWORK DK BLU WIRE DK GRN/WHT WIRE DRL INDICATOR GAUGES FUSE GRN WIRE HEAD- LAMP DIMMER SWITCH HEADLAMPS SWITCH HI BEAM INDICATOR HI LO HOT AT ALL TIMES HOT IN RUN OR START I/P FUSE BLOCK IGNITION SWITCH INSTRUMENT CLUSTER INSTRUMENT CLUSTER SYSTEM LEFT HEAD- LAMP LEFT HI BEAM HEAD- LAMP LO HI LOCK OFF LT GRN WIRE LT GRN/BLK WIRE NEAR BREAKOUT FOR CHASSIS HARNESS) ORG/ WIRE PARK BRAKE IN FOG LAMPS PARK BRAKE INDICATOR SWITCH (ON PARK BRAKE) PARK HEAD OFF PNK IGNITION LAMP FEED HI BM FEED HI BM INDICATOR DRL RELAY CTRL GROUND WIRE PNK WIRE RIGHT HEAD- LAMP RIGHT HI BEAM HEAD- LAMP RUN WIRE TAN WIRE TAN/WHT WIRE WHT WIRE YEL WIRE

1996 VFTC ACCY BLK WIRE BLK/WHT WIRE BULB TEST DAYTIME RUNNING LAMPS (DRL) MODULE (ATTACHED TO I/P HARNESS AT STEERING COLUMN) DAYTIME RUNNING LAMPS (DRL) RELAY (ON MAIN SUPPORT BRACKET AT DRIVER'S ISLAND) DIODE NETWORK DK BLU WIRE DK GRN/WHT WIRE DRL INDICATOR GAUGES FUSE GRN WIRE HEAD- LAMP DIMMER SWITCH HEADLAMPS SWITCH HI LO HOT AT ALL TIMES HOT IN RUN OR START I/P FUSE BLOCK IGNITION SWITCH INSTRUMENT CLUSTER INSTRUMENT CLUSTER SYSTEM HI BEAM INDICATOR LEFT HEAD- LAMP LO HI LOCK OFF LT GRN WIRE LT GRN/BLK WIRE NEAR BREAKOUT FOR CHASSIS HARNESS) ORG/ WIRE PARK BRAKE IN FOG LAMPS PARK BRAKE INDICATOR SWITCH (ON PARK BRAKE) PARK HEAD OFF PNK IGNITION LAMP FEED HI BM FEED HI BM INDICATOR DRL RELAY CTRL GROUND WIRE PNK WIRE RIGHT HEAD- LAMP RUN WIRE TAN WIRE TAN/WHT WIRE WHT WIRE YEL WIRE

4 13 PNK WIRE A/T ABS IND. ACCY BULB TEST LOCK OFF ANTI-LOCK BRAKES SYSTEM AUTO PARK IND. BLK WIRE BLK/WHT WIRE BRAKE IND DRL IND BRN/WHT WIRE CHECK GAUGES IND COOLANT TEMPERATURE GAUGE DIESEL DK BLU WIRE DK GRN WIRE DOOR AJAR IND ECM 1 FUSE 12 ENGINE CONTROLS OR STARTING/ CHARGING SYSTEM ENGINE CONTROLS SYSTEM ENGINE CONTROLS SYSTEM ENGINE CONTROLS SYSTEM ENGINE COOLANT LEVEL SWITCH (ON LOWER LEFT END OF RADIATOR SURGE TANK) FUEL GAUGE FUEL SENDER (ON TOP OF FUEL TANK) GAS GAUGES FUSE 8 GRY WIRE GRY/BLK WIRE HEADLIGHTS SYSTEM HI-BEAM IND HOT IN RUN OR START I/P FUSE BLOCK (BEHIND DASH PANEL) (BODY BUILDER INSTALLED) IGNITION SWITCH ILLUMINATION IN-LINE CONNECTOR PROVISIONS FOR BODY BUILDER INSTRUMENT CLUSTER INTERIOR LIGHTS SYSTEM WARNING SYSTEMS LEFT TURN IND LOW COOLANT IND LT BLU WIRE LT GRN (OR WHT) WIRE LT GRN WIRE LT GRN/BLK WIRE MALFUNCTION IND. LAMP (MIL) (SERVICE ENGINE SOON IND) OIL PRESSURE GAUGE PNK WIRE PPL PPL DIESEL PPL GAS PPL RIGHT TURN IND RUN WIRE SEAT BELT IND SERVICE THROTTLE SOON IND SPEEDOMETER TACHOMETER TAN WIRE TAN/WHT WIRE VEHICLE CONTROL MODULE (ON LEFT SIDE OF RADIATOR SUPPORT) VOLTMETER VSS CALIBRATOR (LEFT SIDE OF DRIVER'S ISLAND, UNDER RELAY BRACKET) WAIT TO START IND WATER IN FUEL IND WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

ACCY AUTO APPLY FUSE 19 BATTERY JUNCTION BLOCK BLK WIRE BLK/WHT WIRE BRAKE PRESSURE DIFFERENTIAL SWITCH (INTERNAL TO ELECTRONIC BRAKE CONROL MODULE) DAYTIME RUNNING LAMPS MODULE DIODE DIODE NETWORK (DASH HARN, DK GRN WIRE ELECTRONIC BRAKE CONTROL MODULE (EBCM) (BELOW RADIATOR, ON LOWER CROSSMEMBER) FROM FUSE BLOCK) FUSE BLOCK FUSIBLE LINK GAS DIESEL HOT AT ALL TIMES HOT IN RUN OR START I/P FUSE BLOCK (BEHIND DASH PANEL) (BODY BUILDER INSTALLED) IGNITION SWITCH LOCK OFF LT BLU WIRE LT GRN WIRE NCA WIRE ORG/ WIRE PARK BRAKE ACTUATOR POSITION SWITCH PARK BRAKE ALARM PARK BRAKE ALARM RELAY (ON I/P HARNESS) (BODY BUILDER INSTALLED) PARK BRAKE PULL BUTTON RELAY (ON I/P HARNESS) (BODY BUILDER INSTALLED) PARK/NEUTRAL POSITION SWITCH RELAY (ON RIGHT SIDE OF DRIVER'S ISLAND) PNK PNK WIRE PNK WIRE PNK/BLK WIRE PPL RED WIRE RUN WIRE SHIFT INTERLOCK SYSTEM TAN/WHT WIRE W/ DRL W/ DRL W/O DRL PARK BRAKE INDICATOR SWITCH (BODY BUILDER INSTALLED) W/O DRL WHT WIRE YEL WIRE YEL/BLK WIRE

1996 VFTC ACC BUS AUTOMATIC TRANSMISSION AUTOMATIC TRANSMISSION (A/T) BRN WIRE CLUTCH PEDAL POSITION (CPP) SWITCH CRK (START) LOCK ON (RUN) OFF CRK (START) ON (RUN) LOCK OFF CRK (START) ON (RUN) OFF DIESEL DK BLU WIRE ENG 1 FUSE EVAPORATIVE EMISSIONS (EVAP) CANISTER PURGE SOLENOID VALVE FROM FUSIBLE LINK FUEL HEATER FUSE OUTPUT- ACCESSORY TYPE 3 FUSE GAS GLOW PLUG CONTROL SWITCH HEATED OXYGEN SENSOR HEATED OXYGEN SENSOR CAMSHAFT POSITION (CMP) SENSOR I/P FUSE BLOCK (DASH PANEL PROVIDED BY BODY BUILDER) (BODY BUILDER INSTALLED) IGNITION SWITCH LEFT POST CONVERTER (5.7L VIN R LEFT PRE- CONVERTER LINEAR EXHAUST GAS RECIRC- ULATION (EGR) SOLENOID VALVE LOCK MANUAL TRANSMISSION MASS AIR FLOW (MAF SENSOR) NCA WIRE ORG/ WIRE PARK/NEUTRAL POSITION (PNP), BACKUP LAMPS SWITCH PNK PNK WIRE PNK WIRE POST CONVERTER (4.3L VIN W PROVISIONS FOR WIPER/ WASHER MOTOR RADIO FUSE RED WIRE RIGHT POST CONVERTER (5.7L VIN R RIGHT PRE- CONVERTER TO I/P FUSE BLOCK: (AUX, I-3, TURN B/U,, HTR FUSES) TRANS FUSE VEHICLE CONTROL MODULE (VCM) WATER- IN-FUEL SENSOR AUXILIARY ENGINE COOLANT FAN RELAY WHT WIRE WINDSHIELD WIPER/ WASHER SWITCH WIPER FUSE YEL 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 AND FUEL TANK SENDER (ON TOP OF FUEL TANK) FUEL PUMP/ OIL PRESSURE SWITCH (ON TOP LEFT REAR OF ENGINE) GAUGES FUSE 8 GRY WIRE HOT AT ALL TIMES HOT IN RUN AND START I/P FUSE BLOCK 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 OIL PRESS GAUGE ORG/ 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 TAN WIRE THROTTLE POSITION SENSOR (ON THROTTLE BODY, TOP OF ENGINE) TRANS FUSE 17 WHT WIRE YEL WIRE

1223 1222 SHIFT SOL B OUT SHIFT SOL A OUT HIGH IDLE SW OUT 3-2 CTRL OUT 1225 1226 419 RANGE MODE SEL B RANGE MODE SEL C SERV ENG SOON IND CTRL 465 1229 FUEL PMP RLY CTRL FORCE MOTOR HI 470 OR 452 496 1456 KNOCK SENS INPUT EGR INPUT A/T INPUT SPEED SENSOR (ON AUTO TRANSMISSION LEFT CENTER) BLK WIRE BLK/RED WIRE BLK/WHT WIRE BLU WIRE BREAKOUT FOR ENGINE COOLANT FAN MOTOR) BRN WIRE BRN/WHT WIRE BYPASS 5 VOLTS SENS GROUND SENS GROUND TRANS TEMP INPUT DIAG ENABLE-POWERTRAIN TP SENS IN DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE ECT SENS INPUT EGR SOL OUT ELECTRONIC 4-SPD AUTOMATIC OVERDRIVE TRANSMISSION EVAPORATIVE CANISTER PURGE SOLENOID (TOP LEFT CENTER OF INTAKE MANIFOLD) FUEL INJ CTRL GRN WIRE GRY WIRE HOT IN RUN, START (CRANK) I/P FUSE BLOCK (MOUNTED ON THE I/P) IDLE AIR CONTROL VALVE MOTOR (ON LEFT SIDE OF THROTTLE BODY INTAKE) KNOCK SENSOR (KS) (ON RIGHT SIDE OF ENGINE BLOCK AHEAD OF STARTER) LT BLU/BLK WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE LT GRN/WHT WIRE LT LT LT PNK PNK WIRE OIL PRESS INPUT MAP SENS INPUT ORG/ WIRE OXYGEN SENSOR (IN EXHAUST STREAM AHEAD OF MUFFLER) PCM GROUND PNK IGNITION CAN PURGE SOL OUT WIRE PNK PNK 26 27 WIRE PNK WIRE POWERTRAIN CONTROL MODULE (PCM) (ON LEFT SIDE OF DRIVER'S ISLAND) PPL PPL 16 17 18 19 PPL 420 474 BRAKE SW INPUT PPL/WHT WIRE RANGE MODE SELECTOR RED WIRE RED/BLK WIRE SHIFT SOL. SHIFT SOL. SHIFT SOL. SHIFT SOL. FORCE MOTOR TAN WIRE TAN/BLK WIRE TRANS FUSE TRANS TEMP WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

4 7 8 9 11 12 13 15 VSS OUT VSS RETURN GROUND BLK WIRE BLK/RED WIRE BREAKOUT FOR ENGINE COOLANT FAN MOTOR, TOWARD CRUISE CONTROL MODULE) BRN WIRE BRN/WHT WIRE CONTACT CRUISE CONTROL MODULE (ON RADIATOR SUPPORT BRACKET) DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE ECM BAT FUSE ENG 1 FUSE ENGINE COOLANT TEMPERATURE SENSOR (FRONT, CENTER OF ENGINE COOLANT INTAKE) FROM BREAKOUT FOR CRUISE CONTROL MODULE, TOWARD ENG) FROM BREAKOUT FOR GENERATOR) GRY WIRE HOT AT ALL TIMES HOT IN RUN HOT IN RUN, START (CRANK) I-3 FUSE I/P FUSE BLOCK (MOUNTED ON THE I/P) IDLE SPEED CONTROL ACTUATOR (ON THROTTLE BODY) LEFT BULK- HEAD GROMMET UNDER I/P) LINEAR EGR SOLENOID VALVE (NO COMPONENT LOCATION AVAILABLE) LT GRN WIRE LT GRN/BLK WIRE ORG/ WIRE PNK 9 10 11 12 13 14 15 16 WIRE PNK PNK 1 2 3 4 5 WIRE PNK PNK 26 27 WIRE PNK WIRE PPL PPL 16 17 18 19 PPL TCC/STOPLAMP INPUT PPL/WHT WIRE RED WIRE TAN WIRE TAN/BLK WIRE THROTTLE POSITION SENSOR (ON LEFT SIDE OF THROTTLE BODY) VEHICLE SPEED SENSOR (ON LEFT REAR SIDE OF TRANSMISSION) VEHICLE SPEED SENSOR BUFFER (ON DRIVER'S ISLAND SUPPORT ABOVE ACCELERATOR PEDAL) VSS VSS LO VSS SIG VSS HI SECOND. VSS WHT WIRE YEL WIRE