GMC Pickup C2500 (1985-2000) org/ Wiring diagrams

1-2 SHIFT SOL 2-3 SHIFT SOL 3-2 SHIFT SOL TRANS FLUID TEMP (TFT) SENSOR BLK WIRE BLK/WHT WIRE BLK/YEL WIRE BRAKE FUSE 18 BRN WIRE BRN/WHT WIRE DATA LINK CONNECTOR (BELOW LEFT SIDE OF DASH) DK BLU WIRE DK BLU/WHT WIRE ECM I FUSE ECM-B FUSE ENGINE COOLANT TEMPERATURE (ECT) SENSOR (TOP FRONT OF ENGINE) GAGES FUSE 4 GRY WIRE HOT AT ALL TIMES HOT IN RUN HOT IN RUN OR START HOT IN RUN, BULB TEST OR START I/P FUSE BLOCK INSTRUMENT CLUSTER LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE ORG/ WIRE PNK WIRE POWERTRAIN CONTROL MODULE (PCM) (UNDER RIGHT END OF DASH) PPL PPL PNK WIRE PPL/WHT 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/STOPLAMP SWITCH (ON BRAKE PEDAL BRACKET) THROTTLE POSITION SENSOR (RIGHT SIDE OF TBI) TRANS FUSE 20 TRANSMISSION TRANSMISSION INPUT SHAFT SPEED SENSOR (FRONT OF TRANSMISSION) UNDERHOOD FUSE/RELAY CENTER VEHICLE SPEED SENSOR BUFFER (UNDER RIGHT END OF DASH) WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

4000 PULSES/MILE CRUISE STATUS BLK WIRE BLK/WHT WIRE BLU WIRE BRAKE FUSE 18 STOP/HAZ FUSE 1 BRN WIRE BRN/WHT WIRE CLUTCH PEDAL SWITCH (TOP OF CLUTCH PEDAL) CRUISE CONTROL MODULE (LEFT REAR OF ENGINE COMPARTMENT) CRUISE CONTROL SWITCH CRUISE FUSE 6 CRUISE ON INPUT SET/COAST INPUT RESUME/ACCEL INPUT CRUISE STATUS VEHICLE SPEED INPUT DISENGAGE INPUT GROUND IGNITION BRAKE APPLIED INPUT DK BLU WIRE DK GRN/WHT WIRE GRY WIRE GRY/BLK WIRE HOT AT ALL TIMES HOT IN RUN I/P FUSE BLOCK LT BLU/BLK WIRE LT GRN/BLK WIRE M/T A/T OFF OR 379 451 ORG/ WIRE PPL PPL/WHT WIRE R/A S/C DK STOPLAMP SWITCH (TOP OF BRAKE PEDAL) VEHICLE CONTROL MODULE (VCM) (LEFT SIDE OF ENGINE COMPT) VEHICLE SPEED SENSOR (VSS) (LEFT SIDE OF TRANSMISSION) VSS RETURN VSS SIGNAL WHT WIRE

1-2 SHIFT SOL 1-2 SHIFT SOLENOID 2-3 SHIFT SOL 2-3 SHIFT SOLENOID A/T ISS SENS HI IN A/T ISS SENS IN A/T ISS SENS LO IN A/T ISS SENSOR OUT ACCELERATOR PEDAL POSITION MODULE (PART OF ACCELERATOR PEDAL) APP 1 SIGNAL IN APP 2 SIGNAL IN APP 3 SIGNAL IN AUTOMATIC TRANSMISSION AUTOMATIC TRANSMISSION INPUT SHAFT SPEED SENSOR (LEFT FRONT OF TRANSMISSION) BATTERY IN BLK WIRE BLK/WHT WIRE BLU/WHT WIRE BRAKE FUSE 18 BRAKE SWITCH ASSEMBLY (ON BRAKE PEDAL BRACKET) BRAKE SWITCH IN BRN WIRE BRN/WHT WIRE CLASS II DATA DK BLU WIRE DK GRN WIRE ECM-B FUSE ECT SENSOR IN ENGINE COOLANT TEMP SENSOR (NEAR THERMOSTAT HOUSING) FRONT WHEEL LOCK FUEL PUMP, OIL PRESS SWITCH/ SENDER, FUEL PUMP RELAY GAUGES FUSE 4 GROUND GRY WIRE GRY/BLK WIRE HI PPL HOT AT ALL TIMES HOT IN RUN HOT IN RUN OR START HOT IN RUN OR START UNDERHOOD FUSE/RELAY CENTER ECM 1 FUSE HOT IN RUN, BULB TEST OR START 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 PNK WIRE PNK WIRE POWER POWERTRAIN CONTROL MODULE (RIGHT SIDE OF DASH NEAR BLOWER MOTOR) PPL PPL DATA LINK CONNECTOR (UNDER LEFT SIDE OF DASH) PPL/WHT WIRE PRESS CTRL SOLENOID LO RED WIRE RED/BLK WIRE SENSOR GROUND STOP/HAZ FUSE 1 STOPLAMP SWITCH IN TAN WIRE TAN/WHT WIRE TCC PWM SOL TCC PWM SOLENOID TFT SENSOR IN TRANS FLUID TEMP SENSOR TRANS FUSE 20 TRANS RANGE "A" TRANS RANGE "B" TRANS RANGE "C" TRANS RANGE PRESSURE SWITCH ASSEMBLY TRANS RANGE SWITCHES TRANSFER CASE CIRCUIT PNK WIRE TRANSFER CASE, AXLE SWITCHES TURN/ HAZARD SWITCH, CHIME MODULE VEHICLE SPEED SENSOR VEHICLE SPEED SENSOR (VSS) ADAPTOR VEHICLE SPEED SENSOR BUFFER (RIGHT SIDE OF DASH) VSS HI IN VSS IN VSS LO IN VSS OUT WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

1-2 SHIFT SOL 2-3 SHIFT SOL 3-2 SHIFT SOL TRANS FLUID TEMP (TFT) SENSOR 999 998 961 452 389 995 PPL ACCELERATOR PEDAL POSITION (APP) MODULE (TOP OF ACCEL- ERATOR BRACKET) APP #3 APP #3 SENSOR SIG APP 1 APP 2 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 GRN WIRE ECM I FUSE ECM-B FUSE ENGINE COOLANT TEMPERATURE (ECT) SENSOR (LEFT LOWER FRONT OF ENGINE BLOCK) GAUGES FUSE GRY 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 LT GRN/BLK WIRE ORG/ WIRE PNK IGNITION FEED 3-2 CONTROL SOL DIAGNOSTIC REQUEST WIRE PNK WIRE POWERTRAIN CONTROL MODULE (UNDER RIGHT SIDE OF DASH) PPL PPL TCC/BRAKE SW PPL/WHT WIRE PRESSURE CONTROL SOLENOID RANGE MODE SELECTOR RED WIRE RED/BLK WIRE SERVICE ENGINE SOON SPEED SENSOR (LEFT REAR SIDE OF TRANSMISSION) STOP/HAZ FUSE 1 TAN WIRE TAN/BLK WIRE TCC PWM SOL TCC SOL TCC/STOP LAMP SWITCH (ON BRAKE PEDAL SUPPORT BRACKET) TRANS FUSE 20 TRANSFER CASE SWITCH TRANSMISSION UNDERHOOD FUSE/RELAY CENTER VEHICLE SPEED SENSOR BUFFER (UNDER RIGHT END OF DASH) WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

1-2 SHIFT SOL 1-2 SHIFT SOLENOID 2-3 SHIFT SOL 2-3 SHIFT SOLENOID A/T ISS SENS HI IN A/T ISS SENS IN A/T ISS SENS LO IN A/T ISS SENSOR OUT ACCELERATOR PEDAL POSITION MODULE (PART OF ACCELERATOR PEDAL) APP 1 SIGNAL IN APP 2 SIGNAL IN APP 3 SIGNAL IN AUTOMATIC TRANSMISSION AUTOMATIC TRANSMISSION INPUT SHAFT SPEED SENSOR (LEFT FRONT OF TRANSMISSION) BATTERY IN BLK WIRE BLK/WHT WIRE BLU/WHT WIRE BRAKE FUSE 18 BRAKE SWITCH ASSEMBLY (ON BRAKE PEDAL BRACKET) BRAKE SWITCH IN BRN WIRE BRN/WHT WIRE CLASS II DATA DK BLU WIRE DK GRN WIRE ECM-B FUSE ECT SENSOR IN ENGINE COOLANT TEMP SENSOR (NEAR THERMOSTAT HOUSING) FRONT WHEEL LOCK FUEL PUMP, OIL PRESS SWITCH/ SENDER, FUEL PUMP RELAY GAUGES FUSE 4 GROUND GRY WIRE GRY/BLK WIRE HI PPL HOT AT ALL TIMES HOT IN RUN HOT IN RUN OR START HOT IN RUN OR START UNDERHOOD FUSE/RELAY CENTER ECM 1 FUSE HOT IN RUN, BULB TEST OR START 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 PNK WIRE PNK WIRE POWER POWERTRAIN CONTROL MODULE (RIGHT SIDE OF DASH NEAR BLOWER MOTOR) PPL PPL DATA LINK CONNECTOR (UNDER LEFT SIDE OF DASH) PPL/WHT WIRE PRESS CTRL SOLENOID LO RED WIRE RED/BLK WIRE SENSOR GROUND STOP/HAZ FUSE 1 STOPLAMP SWITCH IN TAN WIRE TAN/WHT WIRE TCC PWM SOL TCC PWM SOLENOID TFT SENSOR IN TRANS FLUID TEMP SENSOR TRANS FUSE 20 TRANS RANGE "A" TRANS RANGE "B" TRANS RANGE "C" TRANS RANGE PRESSURE SWITCH ASSEMBLY TRANS RANGE SWITCHES TRANSFER CASE CIRCUIT PNK WIRE TRANSFER CASE, AXLE SWITCHES TURN/ HAZARD SWITCH, CHIME MODULE VEHICLE SPEED SENSOR VEHICLE SPEED SENSOR (VSS) ADAPTOR VEHICLE SPEED SENSOR BUFFER (RIGHT SIDE OF DASH) VSS HI IN VSS IN VSS LO IN VSS OUT WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

AUTOMATIC TRANSFER CASE CONTROL MODULE (BEHIND LEFT SIDE OF DASH) AUX PWR FUSE 7 BLK WIRE BLK/WHT WIRE DATA LINK CONNECTOR (DLC) (UNDER LEFT SIDE OF DASH, LEFT OF STEERING COLUMN) DIAG ENABLE DIESEL GASOLINE DK GRN WIRE ELECTRONIC BRAKE CONTROL MODULE (EBCM) (ON LEFT SIDE OF ENGINE COMPT) EXCEPT LUXURY HOT AT ALL TIMES I/P FUSE BLOCK INFLATABLE RESTRAINT SENSING, DIAGNOSTIC MODULE (UNDER DRIVER'S SEAT CARPET) ORG/ WIRE PPL PPL DATA CLSS 2 PROG ENABLE RADIO REMOTE CONTROL DOOR LOCK RECEIVER (BEHIND CENTER OF DASH) SERIAL DATA TAN WIRE TAN/WHT WIRE UART DATA VEHICLE CONTROL MODULE (VCM) (ON LEFT SIDE OF ENGINE COMPT) VEHICLE INTERFACE UNIT

BLK WIRE CIG LTR FUSE 13 CONVENIENCE CENTER (UNDER LEFT SIDE OF I/P) HOT AT ALL TIMES I/P FUSE BLOCK LEFT POWER LUMBAR SUPPORT SWITCH NCA WIRE ORG/ WIRE PUMP RIGHT POWER LUMBAR SUPPORT SWITCH W/ BENCH SEAT W/ BUCKET AND SPLIT BENCH SEAT

BLK WIRE BLU WIRE BRN WIRE CONVENIENCE CENTER (UNDER LEFT SIDE OF DASH) DK BLU WIRE DK GRN WIRE DK PPL DOWN HEADLAMP, PANEL DIMMER SWITCH HOT AT ALL TIMES HOT IN RUN I/P FUSE BLOCK (UNDER LEFT SIDE OF DASH) LEFT FRONT LEFT FRONT POWER WINDOW MASTER SWITCH LEFT FRONT WINDOW MOTOR LEFT REAR LEFT REAR WINDOW MOTOR LEFT REAR WINDOW SWITCH LT BLU WIRE LT GRN WIRE ORG/ WIRE PK LPS FUSE PPL PWR WDO CIRCUIT BREAKER RIGHT FRONT RIGHT FRONT WINDOW MOTOR RIGHT FRONT WINDOW SWITCH RIGHT REAR RIGHT REAR WINDOW MOTOR RIGHT REAR WINDOW SWITCH SOLID STATE TAN WIRE UP DOWN WINDOW LOCKOUT SWITCH YEL WIRE

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 RR+ RR- ANTENNA BARE BLK WIRE BRN WIRE CIG LTR FUSE 13 DIESEL GAS DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE GRY WIRE HOT AT ALL TIMES HOT IN ACC OR RUN I/P FUSE BLOCK LEFT FRONT SPEAKER LEFT FRONT TWEETER LEFT REAR DOOR SPEAKER LEFT REAR SPEAKER LR DR - RLY SIG GROUND LR DR + LR+ LR- RR DR + LT BLU WIRE LT GRN WIRE NCA WIRE ORG/ WIRE ORG/BLK WIRE PNK WIRE POWER AMPLIFIER (UNDER LEFT SIDE OF DASH) POWER AMPLIFIER RELAY (UNDER LEFT SIDE OF DASH) PPL/WHT WIRE RADIO RADIO BATT FUSE 19 RADIO FUSE 17 RED WIRE REMOTE AUDIO PLAYER RIGHT FRONT SPEAKER RIGHT FRONT TWEETER RIGHT REAR DOOR SPEAKER RIGHT REAR SPEAKER RR DR - SERIAL DATA VSS SIGNAL RR - RR + LR _ LR + TAN WIRE VEHICLE CONTROL MODULE (LEFT SIDE OF ENGINE COMPARTMENT) VEHICLE SPEED SENSOR BUFFER (BEHIND RIGHT SIDE OF DASH) VSS SIGNAL WHT WIRE YEL WIRE

ANTENNA BARE BLK WIRE BRN WIRE DIESEL GAS DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE GRY WIRE HOT AT ALL TIMES HOT IN ACC OR RUN I/P FUSE BLOCK LEFT FRONT SPEAKER LEFT FRONT TWEETER LEFT REAR SPEAKER LT BLU WIRE LT GRN WIRE NCA WIRE ORG/ WIRE ORG/BLK WIRE PPL/WHT WIRE RADIO RADIO BATT FUSE 19 RADIO FUSE 17 REMOTE AUDIO PLAYER RIGHT FRONT SPEAKER RIGHT FRONT TWEETER RIGHT REAR SPEAKER SERIAL DATA VSS SIGNAL RR - RR + LR _ LR + TAN WIRE VEHICLE CONTROL MODULE (LEFT SIDE OF ENGINE COMPARTMENT) VEHICLE SPEED SENSOR BUFFER (BEHIND RIGHT SIDE OF DASH) VSS SIGNAL YEL WIRE