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 A/C COMPRESSOR RELAY, GENERATOR, SEAT BELT/ HEADLAMPS ALARM MODULE A/T INPUT SPEED SENSOR (LEFT SIDE OF TRANSMISSION) A/T ISS HI IN A/T ISS LO IN A/T OUTPUT SPEED SENSOR ANTI-LOCK BRAKES, CRUISE CONTROL, SHIFT INTERLOCK SYSTEMS AUTOMATIC TRANSMISSION BATTERY IN BLK WIRE BLK/WHT WIRE BRAKE SWITCH INPUT BRN WIRE BRN/WHT WIRE BUSS BAR GAUGES FUSE 8 DATA CLASS II DK BLU WIRE DK BLU/WHT 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 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 TP SENS INPUT TRANS FLUID TEMP SENSOR TRANS FUSE 17 TRANS RANGE PRESSURE SWITCH ASSEMBLY TRANS TEMP SIG IN TWISTED WIRE PAIR VEHICLE CONTROL MODULE (CENTER FRONT OF ENGINE COMPT) VEHICLE SPEED SENSOR (LEFT REAR OF TRANSMISSION) VSS HI VSS LO YEL WIRE YEL/BLK WIRE

BLK WIRE BLU WIRE BREAKOUT FOR HEADLAMP SW) BULB TEST DAYTIME RUNNING LAMPS MODULE (ATTACHED TO I/P HARNESS AT STEERING COLUMN) DAYTIME RUNNING LAMPS RELAY (ON MAIN SUPPORT BRACKET AT DRIVER'S ISLAND) DIODE NETWORK DK BLU WIRE DK GRN/WHT WIRE DRL INDICATOR FUSIBLE LINK (16 GA- GAUGES FUSE GRN WIRE HEAD- LAMP DIMMER SWITCH HEADLAMPS SWITCH HI BEAM INDICATOR HOT AT ALL TIMES HOT IN RUN OR START I/P FUSE BLOCK IGNITION SWITCH INSTRUMENT CLUSTER INSTRUMENT CLUSTER SYSTEM LEFT HEAD- LAMP LO HI HI LO LOCK OFF LT BLU WIRE LT GRN WIRE LT GRN/BLK WIRE LT LT 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 RELAY OUT GROUND WIRE PNK WIRE RED WIRE RIGHT HEAD- LAMP RUN WIRE TAN WIRE WHT WIRE YEL WIRE

1995 VFTC BLK WIRE DK GRN WIRE HIGH A NOTE HORN (BODY BULDER INSTALLED) HORN RELAY (BEHIND LEFT SIDE OF DASH) HORN SWITCH HORN/DM FUSE 3 HOT AT ALL TIMES I/P FUSE BLOCK (BODY BULDER INSTALLED) (BEHIND DASH PANEL) LOW F NOTE HORN (BODY BULDER INSTALLED) NCA WIRE ORG/ WIRE SLIP RING STEERING COLUMN)

1995 VFTC BLK WIRE BODY BUILDER CONNECTOR (PARTIAL) DK GRN WIRE HORN RELAY HORN SWITCH HOT AT ALL TIMES HORN/DM FUSE I/P FUSE BLOCK LEFT HORN (BODY BUILDER INSTALLED) ORG/ WIRE RIGHT HORN STEERING WHEEL)

A/C COMPRESSOR RELAY ACCESSORY JUNCTION BLOCK (LEFT INTERIOR BULKHEAD, NEAR RELAY BRACKET) AUXILIARY ENGINE COOLANT FAN RELAY (DIESEL ONLY) GLOW PLUG CONTROLLER (DIESEL) BATT BUS BATTERY BATTERY JUNCTION BLOCK (LEFT SIDE OF ENGINE BULKHEAD) BLK WIRE BLU WIRE DATA LINK CONNECTOR DIESEL DOME LAMP (PROVISIONS FOR) ECM-BAT FUSE 6 ELECTRONIC BRAKE CONTROL MODULE ENG BAT FUSE 10 FUEL PUMP RELAY VEHICLE CONTROL MODULE FUSIBLE LINK (10 GA-RUST) FUSIBLE LINK (12 GA- FUSIBLE LINK (14 GA- FUSIBLE LINK (16 GA- FUSIBLE LINK (18 GA- GAS GENERATOR GRY WIRE HAZARD LAMP FLASHER HEADLAMPS SWITCH HORN DM FUSE 3 HORN RELAY I/P FUSE BLOCK (DASH PANEL PROVIDED BY BODY BUILDER) ORG/ WIRE OTHERS POWERTRAIN CONTROL MODULE PWR BUS PWR CIRCUIT BREAKER RED WIRE REMOTE BATTERY ACCESS TERMINAL BLOCK (REAR OF RIGHT RADIATOR CORE SUPPORT PANEL) SEAT BELT ALARM MODULE SECONDARY BATTERY (DIESEL ONLY) STARTER RELAY STARTER SOLENOID STOP-HAZ FUSE 11 STUD TAIL LPS FUSE 7 TO IGNITION SWITCH (DIAGRAM 2 OF 4) TORQUE CONVERTER CLUTCH, STOPLAMPS SWITCH TRANSMISSION CONTROL MODULE (A/T ONLY) FUEL PUMP RELAY W/DELUXE SCHOOL BUS OPTION

4.3L A/T ACC BUS AUTOMATIC TRANSMISSION AUXILIARY ENGINE COOLANT FAN RELAY BRN WIRE CAMSHAFT POSITION SENSOR (5.7L) CLUTCH PEDAL POSITION SWITCH COLD ADVANCE SOLENOID AND ENGINE COOLANT TEMPERATURE SWITCH FUEL HEATER CRANK FUSE 18 CRK (START) LOCK ON (RUN) OFF CRK (START) ON (RUN) LOCK OFF CRK (START) ON (RUN) OFF DIESEL DK BLU WIRE ENG 1 FUSE 15 ENGINE SHUT-OFF SOLENOID FUEL SOLENOID DRIVER EVAP CANISTER VENT VALVE (4.3L) EVAPORATIVE EMISSIONS CANISTER PURGE VALVE FROM FUSIBLE LINK GAS GLOW PLUG CONTROLLER HEATED OXYGEN SENSOR BANK 1 SENSOR 1 CAMSHAFT POSITION SENSOR (4.3L) HEATED OXYGEN SENSOR BANK 2 SENSOR 1 HEATED OXYGEN SENSOR BANK 1 SENSOR 2 HEATED OXYGEN SENSOR BANK 2 SENSOR 2 IGNITION SWITCH IN-LINE FUSE BLOCK (NEAR RIGHT SIDE OF STEERING COLUMN) LOCK M/T MASS AIR FLOW SENSOR (4.3L/ 5.7L) ORG/ WIRE PARK/NEUTRAL POSITION AND BACKUP LAMPS SWITCH PNK PNK WIRE PNK WIRE PROVISIONS FOR WINDSHIELD WASHER MOTOR RADIO FUSE 4 RED WIRE TO I/P FUSE BLOCK (DIAGRAM 4 OF 4) TRANS FUSE 17 WATER IN FUEL INDICATOR SENSOR WHT WIRE WINDSHIELD WIPER/ WASHER SWITCH WIPER FUSE 14 YEL WIRE

1996 VFTC 6.5L ENGINE A/C COMPRESSOR RELAY A/T AUX CIRCUIT BREAKER 13 AUX FUSE BACK UP LAMPS SWITCH BRN WIRE CB CB I-3 FUSE 9 DAYTIME RUNNING LAMP RELAY INSTRUMENT CLUSTER DAYTIME RUNNING LAMPS CONTROL MODULE DIESEL DK GRN WIRE ECM 1 FUSE 12 ELECTRONIC BRAKE CONTROL MODULE FROM ENG-1 FUSE (DIAGRAM 2 OF 4) FROM IGNITION SWITCH (DIAGRAM 2 OF 4) FROM VCM BREAKOUT) FUEL INJECTION PUMP SHUT-OFF SOLENOID GAS GAUGES FUSE 8 GENERATOR GENERATOR GLOW PLUG CONTROLLER (FEDERAL) GRY WIRE HTR BUS HTR FUSE 1 I/P FUSE BLOCK (DASH PANEL PROVIDED BY BODY BUILDER) IGN BUS INSTRUMENT CLUSTER INSTRUMENT LAMPS FUSE INTERIOR LIGHTS SYSTEM (I/P LAMPS DIMMER SWITCH) M/T ORG/ WIRE OTHERS PARK/ NEUTRAL POSITION AND BACKUP LAMPS SWITCH PNK (ENGINE HARNESS, APPROX 26 CM FROM BULKHEAD GROMMET) WIRE PNK PNK PNK WIRE PNK PNK WIRE PNK WIRE POWERTRAIN CONTROL MODULE (ELEC) SEAT BELTS ALARM MODULE TORQUE CONVERTER CLUTCH, STOP LAMPS SWITCH TURN B/U FUSE 5 TURN SIGNAL FLASHER VEHICLE CONTROL MODULE (VCM) WATER IN FUEL INDICATOR SENSOR FUEL HEATER GLOW PLUG CONTROLLER (CALIF)

7.4L 7.4L VIN J 6.5L VIN F A/C COMPRESSOR RELAY FAN CONTROL RELAY ALTERNATOR BATTERY BATTERY JUNCTION BLOCK (ON FORWARD LEFT SIDE OF THE BULKHEAD) BLK WIRE BLU WIRE BUSS BAR CONNECTOR FOR DOME LAMP DATA LINK CONNECTOR DIESEL ECM-BAT FUSE 6 ELECTRONIC BRAKE CONTROL MODULE ENG BAT FUSE 10 FAN CONTROL RELAY GLOW PLUG CONTROLLER FUEL PUMP RELAY FUSIBLE LINK FUSIBLE LINK (10 GA- FUSIBLE LINK (10 GA-RUST) FUSIBLE LINK (14 GA- FUSIBLE LINK (16 GA- FUSIBLE LINK (18 GA. FUSIBLE LINK (12 GA. GRY WIRE HAZARD FLASHER HEADLAMPS SWITCH HEADLAMPS SWITCH STOPLAMP SWITCH HORN DM FUSE 3 HORN RELAY I/P FUSE BLOCK (MOUNTED ON THE DASH) IGNITION SWITCH (DIAGRAM 2 OF 4) ORG/ WIRE PARK BRAKE PUMP MOTOR RELAY POWERTRAIN CONTROL MODULE VEHICLE CONTROL MODULE PWR CIRCUIT BREAKER 2 RED WIRE SEATBELT AND LAMPS ALARM MODULE SECONDARY BATTERY (DIESEL ONLY) STARTER MOTOR STARTER RELAY STOP-HAZ FUSE 11 TAIL LAMPS FUSE 7

6.5L VIN F AUTO APPLY FUSE 19 AUTOMATIC TRANSMISSION BRN WIRE CRANK FUSE 18 DAYTIME RUNNING LAMP CONTROL MODULE DIESEL DIODE NETWORK DK BLU WIRE ENG-1 FUSE TRANS FUSE 17 ENGINE SHUT OFF SOLENOID EVAPORATIVE EMISSIONS CANISTER PURGE VALVE SOLENOID FROM FUSE PANEL) FROM FUSIBLE LINK (DIAGRAM 1 OF 4) FROM I/P FUSE BLOCK) PNK WIRE FUEL SOLENOID DRIVER HARN BREAKOUT) PNK WIRE HEATED OXYGEN SENSOR BANK 1 SENSOR 2 HEATED OXYGEN SENSOR BANK 2 SENSOR 1 CAMSHAFT POSITION SENSOR FAN CONTROL RELAY HEATED OXYGEN SENSOR BANK 2 SENSOR 2 I/P FUSE BLOCK (MOUNTED ON THE DASH) IGNITION SWITCH INSTRUMENT CLUSTER BREAKOUT) INSTRUMENT CLUSTER ENGINE COOLANT LEVEL SWITCH LOCK OFF LT BLU WIRE MASS AIR FLOW SENSOR HEATED OXYGEN SENSOR BANK 1 SENSOR 1 NCA WIRE ORG/ WIRE PARK BRAKE ALARM PARK BRAKE ALARM RELAY PARK BRAKE LOW PRESSURE INDICATOR SWITCH PARK BRAKE PULL BUTTON SWITCH PARK BRAKE PULL BUTTON RELAY PARK BRAKE SWITCH PARK/ NEUTRAL POSITION AND BACKUP LAMPS SWITCH PARK/NEUTRAL POSITION AND BACKUP LAMPS SWITCH PASSTHROUGH 6.5L: ENG HARN, PNK DIMMER SWITCH WIRE PNK PNK WIRE PNK WIRE RADIO FUSE 4 RED WIRE RELAY SOCKETS) RUN WIRE TO AUX FUSE (DIAGRAM 4 OF 4) TO GAUGES FUSE (DIAGRAM 4 OF 4) WHT WIRE WINDSHIELD WIPER MOTOR WIPER FUSE 14 YEL WIRE YEL/BLK WIRE

1996 VFTC 7.4L VIN J ENGINE 7.4L VIN J ENGINES A/C COMPRESSOR RELAY GENERATOR AUX CIRCUIT BREAKER 13 BRN WIRE BUSS BAR CANADIAN MODELS CRUISE CONTROL MODULE CRUISE CONTROL SWITCH DAYTIME RUNNING LAMP RELAY DK GRN WIRE ELECTRONIC BRAKE CONTROL MODULE FROM ENG-1 FUSE (DIAGRAM 2 OF 4) FROM IGNITION SWITCH (DIAGRAM 2 OF 4) GAUGES FUSE 8 GRY WIRE HTR FUSE 1 I-3 FUSE 9 I/P FUSE BLOCK (MOUNTED ON THE DASH) INSTR LPS FUSE 16 INSTRUMENT CLUSTER INTERIOR LIGHTS SYSTEM (INSTRUMENT PANEL DIMMER SWITCH) NCA WIRE ORG/ WIRE PNK PNK WIRE PNK WIRE SEATBELT/ LAMPS ALARM MODULE DAYTIME RUNNING LAMP CONTROL MODULE TO ECM 1 FUSE DIAGRAM 3 OF 4) TORQUE CONVERTER CLUTCH AND STOP LAMPS SWITCH TURN B/U FUSE 5 TURN SIGNAL FLASHER VEHICLE CONTROL MODULE WIPER MOTOR BREAKOUT) PNK WIRE