GMC Forward Control P3500 (1985-1999) org/ 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

B+ BREAKOUT) BATTERY JUNCTION BLOCK (LEFT SIDE OF ENGINE BULKHEAD, ABOVE RELAY BRACKET) BLK WIRE BLU WIRE BRN WIRE BULKHEAD GROMMET) DK BLU WIRE DK GRN WIRE ENG-1 FUSE 20 A FUEL HEATER (REAR OF INTAKE MANIFOLD, PART OF FUEL/WATER SEPARATOR) (FILTER) FUEL INJECTION PUMP COLD ADVANCE SOLENOID (IN FUEL INJECTION PUMP) FUSIBLE LINK FUSIBLE LINK (12 GA- FUSIBLE LINK (14 GA- FUSIBLE LINK (20 GA- FUSIBLE LINK FUSIBLE LINK FUSIBLE LINK FUSIBLE LINK FUSIBLE LINK GLOW PLUG STUD GLOWPLUG CONTROL SWITCH (REAR OF LEFT CYLINDER HEAD) GROUND GRY WIRE HOT AT ALL TIMES HOT IN (ON) RUN, START (CRANK) I/P FUSE BLOCK (DASH PANEL PROVIDED BY BODY BUILDER) (BODY BUILDER INSTALLED) IGN FEED LEFT BANK GLOWPLUGS (CYLINDER HEADS BELOW VALVE COVERS) LEFT GLOWPLUG BREAKOUTS) LT GRN WIRE LT GRN/BLK WIRE NCA WIRE ORG/ WIRE PNK (COIL) WIRE PNK 12 13 15 WIRE PNK IGN FEED IND LAMP OUT GROUND WIRE PNK WIRE POWER DISTRIBUTION SYSTEM PPL (NOT USED) PPL PPL PNK 3 4 5 6 7 8 WIRE PPL STARTER FEED PPL/WHT WIRE PRESSURE DIFF SW BREAKOUT) RED WIRE RIGHT BANK GLOWPLUGS (CYLINDER HEADS BELOW VALVE COVERS) STUD TRANS FUSE VEHICLE SPEED SENSOR (VSS) (LEFT REAR OF TRANSMISSION, NEAR CENTER) VSS RTN GROUND IGN FEED VSS SIG VSS VSS OUT YEL/BLK WIRE

BATTERY JUNCTION BLOCK (LEFT SIDE OF ENGINE BULKHEAD, ABOVE RELAY BRACKET) BLK WIRE BLU WIRE DK BLU WIRE ECM-1 FUSE 20 A ENG-1 FUSE 20 A FUEL HEATER (REAR OF INTAKE MANIFOLD, PART OF FUEL/WATER SEPARATOR) (FILTER) FUEL INJECTION PUMP FUEL SHUT-OFF SOLENOID (AT FUEL INJECTION PUMP) FUSIBLE LINK FUSIBLE LINK (12 GA- FUSIBLE LINK (14 GA- FUSIBLE LINK (20 GA- FUSIBLE LINK FUSIBLE LINK GLOW PLUG STUD GLOWPLUG CONTROL SWITCH (REAR OF LEFT CYLINDER HEAD) GROUND GRY WIRE HOT AT ALL TIMES HOT IN (ON) RUN, START (CRANK) I/P FUSE BLOCK (DASH PANEL PROVIDED BY BODY BUILDER) (BODY BUILDER INSTALLED) IGN FEED LEFT BANK GLOWPLUGS (CYLINDER HEADS BELOW VALVE COVERS) LEFT GLOWPLUG BREAKOUTS) NCA WIRE ORG/ WIRE ORG/BLK WIRE PNK WIRE POWER DISTRIBUTION SYSTEM PPL PPL STARTER FEED RED WIRE RIGHT BANK GLOWPLUGS (CYLINDER HEADS BELOW VALVE COVERS) STUD

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

1 2 3 4 5 6 7 8 PNK PNK WIRE A/C COMP CYL SW A/C REQUEST SIGNAL AIR CONDITIONING SYSTEM ANTI-LOCK BRAKES SYSTEM PPL AUX ELECT COOLING FAN BRAKE SIGNAL SERIAL DATA PPL PPL 420 1807 B(+) BATTERY FEED RANGE SIGNAL B RANGE SIGNAL A 1225 1224 PNK WIRE BLK RED/ WIRE BLK WIRE BLK/WHT WIRE BLU/ 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 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 ECM B FUSE 6 EGR VALVE FEED EGR VLV CTRL ELEC SPK TIMING CTRL SIGNAL EST 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 FUEL PUMP RELAY (LEFT SIDE OF ENGINE COMPT) 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 COIL 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 GROUND GROUND SENS GROUND PNK 22 23 WIRE PNK IGN FEED WIRE PNK WIRE 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 SPARK PLUGS SPEED SENSOR INPUT VEHICLE CONTROL MODULE (VCM) (ON CENTER FRONT OF ENGINE COMPARTMENT) VSS OUTPUT SIGNAL VSS OUTPUT SIGNAL CHECK ENGINE LP CTRL 389 419 WHT DK GRN/ WIRE WHT WIRE WHT/BLK 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

BATTERY JUNCTION BLOCK (ON FORWARD LEFT SIDE OF BULKHEAD) BLK WIRE BLK/RED WIRE BRN WIRE BRN/WHT WIRE BYPASS DIST. REF HI DIST. REF LO DISTRIBUTOR DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE ECM 1 FUSE FUEL GAUGE FUEL PUMP PRIME CONNECTOR FUEL PUMP RELAY (AT RELAY CENTER RIGHT SIDE OF MAIN SUPPORT AT DRIVER'S ISLAND) FUEL PUMP, SENDER (ON TOP OF FUEL TANK) FUSIBLE LINK (16 GA- GAUGES FUSE GRY WIRE HIGH VOLTAGE IGNITION COIL WIRE HOT AT ALL TIMES HOT IN RUN, START (CRANK) I/P FUSE BLOCK (MOUNTED ON THE I/P) IGNITION COIL (ON BRACKET AT REAR OF INTAKE PLENUM) IGNITION MODULE IGNITION SWITCH INSTRUMENT CLUSTER LOCK OFF OIL PRESS GAUGE ORG/ WIRE PICKUP COIL PNK 9 10 11 12 13 14 15 16 WIRE PNK PNK 1 2 3 4 5 WIRE PNK WIRE PPL PPL/WHT WIRE RED WIRE RUN WIRE SERVICE ENGINE SOON INDICATOR SPEED METER TACHOMETER TEST LEAD TAN WIRE TAN/BLK WIRE THROTTLE BODY FUEL INJECTOR NO.1 (ON TOP OF INTAKE MANIFOLD) THROTTLE BODY FUEL INJECTOR NO.2 (ON TOP OF INTAKE MANIFOLD) WHT WIRE