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

1-2 SHIFT SOL 2-3 SHIFT SOL ALT FUSE BLK WIRE BLK/WHT WIRE BLK/YEL WIRE BRAKE FUSE BRN WIRE BRN/WHT WIRE DATA LINK CONNECTOR (BELOW LEFT SIDE OF DASH) DK BLU WIRE DK BLU/WHT WIRE DK GRN/YEL WIRE ECM BAT FUSE ECM I FUSE ENGINE COOLANT TEMPERATURE (ECT) SENSOR (TOP FRONT OF ENGINE) GRY WIRE GRY/RED WIRE HOT AT ALL TIMES HOT IN RUN HOT IN RUN, BULB TEST OR START I/P FUSE BLOCK INSTRUMENT CLUSTER LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE ORG/ WIRE ORG/BLK WIRE PNK WIRE PNK/BLK WIRE POWERTRAIN CONTROL MODULE (PCM) (LEFT SIDE OF DRIVER'S ISLAND) PPL PRESSURE CONTROL SOLENOID RANGE MODE SELECTOR RED WIRE RED/BLK WIRE SERVICE ENGINE SOON SPEED SENSOR (LEFT REAR SIDE OF TRANSMISSION) TAN WIRE TCC PWM SOL TCC/BRAKE SWITCH (ON BRAKE PEDAL BRACKET) THROTTLE POSITION SENSOR (RIGHT SIDE OF TBI) TRANS FLUID TEMP (TFT) SENSOR TRANS FUSE TRANSMISSION TRANSMISSION INPUT SHAFT SPEED SENSOR (FRONT OF TRANSMISSION) VEHICLE SPEED SENSOR BUFFER WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

1-2 SHIFT SOL 2-3 SHIFT SOL ALT FUSE BLK WIRE BLK/WHT WIRE BLK/YEL WIRE BRN WIRE BRN/WHT WIRE DATA LINK CONNECTOR (BELOW LEFT SIDE OF DASH) DK BLU WIRE DK BLU/WHT WIRE ECM BAT FUSE ECM-CRNK FUSE ENGINE COOLANT TEMPERATURE (ECT) SENSOR (TOP FRONT OF ENGINE) GRY WIRE GRY/RED WIRE HOT AT ALL TIMES HOT IN RUN OR START HOT IN RUN, BULB TEST OR START I/P FUSE BLOCK INSTRUMENT CLUSTER LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE ORG/ WIRE ORG/BLK WIRE PNK WIRE PNK/BLK WIRE POWERTRAIN CONTROL MODULE (PCM) (LEFT SIDE OF DRIVER'S ISLAND) PPL PPL PNK WIRE PRESSURE CONTROL SOLENOID RANGE MODE SELECTOR RED WIRE RED/BLK WIRE SERVICE ENGINE SOON SPEED SENSOR (LEFT REAR SIDE OF TRANSMISSION) TAN WIRE TCC PWM SOL TCC/BRAKE SWITCH (ON BRAKE PEDAL BRACKET) THROTTLE POSITION SENSOR (RIGHT SIDE OF TBI) TRANS FLUID TEMP (TFT) SENSOR TRANS FUSE TRANSMISSION TRANSMISSION INPUT SHAFT SPEED SENSOR (FRONT OF TRANSMISSION) VEHICLE SPEED SENSOR BUFFER WHT/BLK WIRE 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/T ISS SENS HI IN A/T ISS SENS LO IN ACCELERATOR PEDAL POSITION (APP) MODULE (THROTTLE PEDAL MOUNT) APP 1 SIGNAL IN APP 2 SIGNAL IN APP 3 SIGNAL IN AUTO TRANSMISSION INPUT SHAFT SPEED SENSOR (INSIDE FRONT OF TRANSMISSION) AUTOMATIC TRANSMISSION BATTERY IN BLK WIRE BRAKE SWITCH ASSEMBLY (ON BRAKE PEDAL BRACKET) BRAKE SWITCH IN BRN WIRE BRN/WHT WIRE CLASS II DATA DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE ECM BATT FUSE ECM I FUSE ECT SENSOR IN ENGINE COOLANT TEMP SENSOR (LEFT LOWER FRONT OF ENGINE) GAUGES FUSE TRANS FUSE GRY WIRE HOT AT ALL TIMES HOT IN RUN HOT IN RUN OR START I-3 FUSE I/P FUSE BLOCK IGNITION IN INSTRUMENT CLUSTER LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE MALFUNCTION INDICATOR LAMP MIL CONTROL ORG/ WIRE PCM GROUND PCS SOL HI OUT PCS SOL LO OUT PNK WIRE POWERTRAIN CONTROL MODULE (ENGINE COMPT, TOP OF RADIATOR SUPPORT) PPL PPL DATA LINK CONNECTOR PPL/WHT WIRE PRESS CTRL SOLENOID RED WIRE RED/BLK WIRE SENSOR GROUND STOP/HAZ FUSE STOPLAMP SWITCH IN TFT SENSOR IN TRANS FLUID TEMP SENSOR TRANS RANGE "A" TRANS RANGE "B" TRANS RANGE "C" TRANS RANGE PRESSURE SWITCH ASSEMBLY VEHICLE SPEED SENSOR (LEFT REAR OF TRANSMISSION) VEHICLE SPEED SENSOR (VSS) BUFFER (ABOVE ACCELERATOR PEDAL) VSS HI IN VSS LO IN VSS OUT YEL WIRE YEL/BLK WIRE

BACKUP LAMP SWITCH (ON STEERING COLUMN) BLK WIRE BLU WIRE BRN WIRE DK BLU WIRE DK GRN WIRE FUSE BLOCK- I/P G# N/A (REAR LAMPS HARNESS) GRN WIRE HAZARD HAZARD FLASHER (TOP LEFT SIDE OF SHIPPING PANEL) HEAD OFF HEADLIGHT SWITCH HOT AT ALL TIMES HOT IN RUN OR START INSTRUMENT CLUSTER LEFT FRONT MARKER LAMP LEFT LICENSE LAMP RIGHT LICENSE LAMP LEFT TAIL/STOP TURN LAMP LEFT TURN INDICATOR LT BLU WIRE LT LT NORMAL ORG/ WIRE PARK PPL PROVISIONS FOR BODY BUILDER ADDED LAMPS PROVISIONS FOR REAR MARKER LAMPS RIGHT BACKUP LAMP LEFT BACKUP LAMP RIGHT FRONT MARKER LAMP RIGHT FRONT PARK/ TURN LAMP LEFT FRONT PARK/ TURN LAMP RIGHT TAIL/STOP TURN LAMP RIGHT TURN INDICATOR STOP/ HAZ FUSE STOPLAMP SWITCH (ON BRAKE PEDAL SUPPORT) TAIL LPS FUSE TURN LEFT TURN RIGHT TURN SIGNAL FLASHER TURN-B/U FUSE TURN/HAZARD SWITCH (UPPER LEFT SIDE OF STEERING COLUMN) WHT WIRE YEL WIRE

BLK WIRE DAYTIME RUNNING LAMPS CONTROL MODULE (ATTACHED TO I/P HARNESS) DAYTIME RUNNING LAMPS RELAY (LEFT SIDE OF DASH, ON RELAY BRACKET) DIODE NETWORK (ON I/P HARNESS) DK BLU WIRE DK GRN/WHT WIRE DRL INDICATOR FUSE BLOCK BREAKOUT) FUSIBLE LINK (16 GA- GAUGES FUSE 8 GRN WIRE HEADLAMP DIMMER SWITCH HEADLAMPS SWITCH OFF HI BEAM INDICATOR HI LO HOT AT ALL TIMES HOT IN RUN OR START I/P FUSE BLOCK IGNITION SWITCH INSTRUMENT CLUSTER LEFT HEAD- LAMP LO HI 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 LEVER) PARK HEAD PNK IGNITION LAMP FEED HI BM INPUT HI BM INDICATOR RELAY CONTROL GROUND WIRE PNK WIRE RED WIRE RIGHT HEAD- LAMP RUN WIRE TAN WIRE WHT WIRE YEL WIRE

BLK WIRE DAYTIME RUNNING LAMP INDICATOR DAYTIME RUNNING LAMPS MODULE (BEHIND LEFT SIDE OF I/P) DAYTIME RUNNING LAMPS RELAY (BEHIND LEFT SIDE OF I/P, ABOVE STEERING COLUMN) DK BLU/WHT WIRE DRL FUSE FUSE BLOCK GAUGES FUSE GRN WIRE HEAD PARK HEADLAMP DIMMER SWITCH HEADLIGHT SWITCH ASSEMBLY HI BEAM INDICATOR HI LO HOT AT ALL TIMES HOT IN RUN OR START IGNITION LAMP FEED HI BEAM FEED HI BEAM INDICATOR OUTPUT TO RELAY GROUND INSTRUMENT CLUSTER LEFT HIGH BEAM HEADLAMP LEFT LOW BEAM HEADLAMP LT GRN WIRE LT GRN/BLK WIRE LT LT OFF OFF HEAD ORG/ WIRE PARK PARK BRAKE WARNING SWITCH (ON PARK BRAKE SUPPORT BRACKET) PNK/BLK WIRE PPL PPL BULB CHECK RIGHT HIGH BEAM HEADLAMP RIGHT LOW BEAM HEADLAMP TAN WIRE WHT WIRE YEL WIRE

BLK WIRE BLU WIRE BRN WIRE DAYTIME RUNNING LAMP CUTOFF RELAY DAYTIME RUNNING LAMP INDICATOR DAYTIME RUNNING LAMPS MODULE (IN I/P HARNESS) DAYTIME RUNNING LAMPS RELAY (IN I/P HARNESS) DK BLU/WHT WIRE DK GRN/YEL WIRE GRN WIRE HEAD PARK HEADLAMP DIMMER SWITCH HEADLIGHT SWITCH ASSEMBLY HI BEAM INDICATOR HI LO HORN/DM FUSE HOT AT ALL TIMES HOT IN RUN OR START FUSE BLOCK HTR FUSE INSTRUMENT CLUSTER LEFT HEADLAMP ASSEMBLY LEFT LOWER HEADLAMP (W/ HPR) LT GRN WIRE LT GRN/BLK WIRE OFF OFF HEAD ORG/ WIRE PARK PARK BRAKE WARNING SWITCH (AT PARK BRAKE, UNDER LEFT SIDE OF I/P) PROVISIONS FOR FOG LAMPS RIGHT HEADLAMP ASSEMBLY RIGHT LOWER HEADLAMP (W/ HPR) TAN WIRE TAN/WHT WIRE WHT WIRE YEL WIRE

1995 VFTC BLK WIRE DK GRN WIRE FUSE BLOCK HORN RELAY HORN SWITCH HOT AT ALL TIMES HORN/DM FUSE LEFT HORN (IN FORWARD LAMP HARNESS) ORG/ WIRE RIGHT HORN (IN FORWARD LAMP HARNESS) STEERING WHEEL)

BLK WIRE BRN WIRE DIM HIGH DK GRN WIRE DOME LAMP SWITCH GRY WIRE HEADLAMPS SWITCH HORN DM FUSE 3 HOT AT ALL TIMES I/P FUSE BLOCK I/P LAMPS DIMMER SWITCH INSTR LPS FUSE 16 INSTRUMENT CLUSTER LIGHT SWITCH OFF HEAD PARK ORG/ WIRE PANEL LAMPS SWITCH PRNDL LAMP PROVISION FOR DOME LAMP PROVISION FOR ROOF MARKER LAMPS SEAT BELT ALARM (BOTTOM OF I/P FUSE BLOCK) TAIL LPS FUSE 7 WHT WIRE

ACC RADIO FUSE ACCY ACCY BULB TEST LOCK ACCY BULB TEST LOCK OFF AUTO APPLY PARK BRAKE AUX CB AUX CIRCUIT BREAKER HTR FUSE AUXILIARY COOLING FAN RELAY AUXILIARY COOLING FAN RELAY DAYTIME RUNNING LAMPS BATTERY BATTERY JUNCTION BLOCK BLK WIRE BLK/RED WIRE BRAKE WARNING ALARM BUZZER BRN WIRE BULB TEST DAYTIME RUNNING LAMPS RELAY DAYTIME RUNNING LAMPS MODULE DK GRN WIRE FROM PANEL DIMMER SWITCH ASSEMBLY (INTERIOR LIGHTS SYSTEM) FUEL PUMP RELAY FUEL PUMP OIL PRESSURE SWITCH HAZARD FLASHER FUSE BLOCK FUSIBLE FUSIBLE LINK GENERATOR GRY WIRE HEADLIGHT SWITCH HORN RELAY HORN/DM I/P CLUSTER BRAKE PRESSURE WARNING SWITCH IGNITION SWITCH INSTRUMENT CLUSTER LINK LOCK OFF LPS BUS GAGES FUSE INSTR-LPS FUSE OFF ORG/ WIRE PARK BRAKE WARNING SWITCH PCM PNK WIRE PNK/ WHT WIRE PNK/BLK WIRE PNK/WHT WIRE POWERTRAIN CONTROL MODULE PPL PWR ECM-BAT CIRCUIT BREAKER FUSE RED WIRE RELAY RUN WIRE SHUNT STARTER MOTOR STOP- HZ FUSE STOPLAMP SWITCH TAIL LPS FUSE FUSE TAN/WHT WIRE TO ALT, ECM-CRNK, TURN-B/U, TRANS, INJ FUSES AND IGNITION COIL TRANSMISSION POSITION INDICATOR LAMP WHT WIRE WINDSHIELD WIPER MOTOR WIPER SWITCH MODULE WIPER FUSE YEL WIRE