GMC Pickup C2500 (1985-2000) blk Wiring diagrams

1 2 3 4 5 6 7 8 9 10 ILLUMINATION GROUND A/C DISABLE AUX FAN CTRL IGNITION A/C COMPRESSOR CLUTCH A/C COMPRESSOR CLUTCH CYCLING SWITCH (IN LOW PRESSURE LINE NEAR COMPRESSOR) A/C COMPRESSOR CLUTCH RELAY (IN UNDERHOOD FUSE/RELAY CENTER) A/C CTRL A/C HIGH PRESSURE CUTOUT SWITCH (AT A/C COMPRESSOR) A/C MAXI FUSE 3 CENTER A/C REQ AUX FAN MINI FUSE AUXILIARY COOLING FAN A/C PRESSURE SWITCH AUXILIARY COOLING FAN MOTOR AUXILIARY COOLING FAN RELAY (7.4L VIN J) (IN UNDERHOOD FUSE/RELAY CENTER) BATTERY IGNITION GROUND DEFOGGER ELEMENT BLK WIRE BLOWER MOTOR BLOWER RESISTOR (UNDER RIGHT SIDE OF I/P, ON HEATER HOUSING) BLOWER SWITCH BRN WIRE DIODE DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE GAS DIESEL GRY WIRE GRY/BLK WIRE HEATER AND A/C CONTROL MODULE HIGH BLOWER RELAY (UNDER I/P ON TOP OF HEATER-A/C CASE) HOT AT ALL TIMES HOT IN RUN HOT IN RUN OR START IGN MINI FUSE A/C COMP MINI FUSE HOT IN RUN, BULB TEST OR START FUSE BLOCK HTR A/C FUSE 12 IGN E MINI FUSE LT BLU WIRE LT GRN WIRE NCA WIRE OFF LO ORG/ WIRE PNK WIRE PPL REAR DEFOGGER SYSTEM RECIRCULATION DOOR MOTOR (UNDER I/P ON HEATER- A/C CASE) RED WIRE TAN WIRE UNDERHOOD FUSE-RELAY UNDERHOOD FUSE-RELAY CENTER VALVE CTRL AIR TEMP DR SENSOR MODE SIGNAL A/C SWITCH WATER VALVE (SUBURBAN, UTILITY, CREW CAB ONLY) (RIGHT CENTER OF INTAKE AREA) WHT WIRE YEL WIRE

ANTI-LOCK IND BATT GROUND BLK WIRE BLK/WHT WIRE BRAKE IND BRAKE PRESSURE WARNING LAMP WARNING (ON MASTER BRAKE CYLINDER) BRAKE WARN IND GROUND BRN WIRE CONVENIENCE CENTER DATA LINK CONNECTOR DIODE (BEHIND LEFT SIDE OF I/P) DK GRN WIRE HOT AT ALL TIMES UNDERHOOD FUSE/RELAY CENTER MAXI- FUSE 4 HOT IN RUN BRAKE FUSE 18 HOT IN RUN, BULB TEST OR START FUSE BLOCK GAGES FUSE 4 IGN FEED ABS IND BRAKE SW INSTRUMENT CLUSTER LEFT FNT SENS LO LEFT FRONT WHEEL SENSOR LT BLU WIRE LT GRN/BLK WIRE PNK WIRE PPL PPL/WHT WIRE RED WIRE RIGHT FRONT WHEEL SENSOR RT FNT SENS LO LEFT FNT SENS HI RT FNT SENS HI TAN WIRE TAN/WHT WIRE TCC/STOPLAMP SWITCH (TOP OF BRAKE PEDAL) VEHICLE SPEED SENSOR (LEFT REAR OF TRANS) VSS BUFFER INPUT DLC WHT WIRE YEL WIRE

A/C COMP FUSE AUX FAN FUSE AUXILIARY COOLING FAN MOTOR AUXILIARY COOLING FAN RELAY (IN UNDERHOOD FUSE/RELAY CENTER) BLK WIRE DK BLU WIRE HOT AT ALL TIMES HOT IN RUN OR START ORG/ WIRE RED WIRE RELAY CTRL UNDERHOOD FUSE BLOCK VEHICLE CONTROL MODULE (LEFT REAR OF ENGINE COMPT)

BLK WIRE BRN WIRE FRT WPR FUSE 11 FUSE BLOCK HOT IN ACCY OR RUN MIST NCA WIRE OFF PULSE PPL RED WIRE SOLID STATE WASH PULSE SWITCH WINDSHIELD WASHER MOTOR WIPER MOTOR MODULE WIPER/ WASHER SWITCH YEL WIRE

1 2 3 4 5 6 7 8 9 10 ILLUMINATION GROUND A/C MAXI FUSE 3 AIR TEMP DR SENSOR MODE SIGNAL BATTERY IGNITION GROUND DEFOGGER ELEMENT BLK WIRE BLOWER MOTOR BLOWER RESISTOR (UNDER RIGHT SIDE OF I/P, ON HEATER HOUSING) BLOWER SWITCH BRN WIRE DK BLU WIRE DK GRN WIRE FRONT MODE DOOR MOTOR (UNDER I/P ON HEATER- A/C CASE) FRONT TEMPERATURE DOOR MOTOR (UNDER I/P ON HEATER- A/C CASE) FUSE BLOCK GRY WIRE HEATER AND A/C CONTROL MODULE HIGH BLOWER RELAY (UNDER I/P ON TOP OF HEATER-A/C CASE) HOT IN RUN HTR A/C FUSE 12 LT BLU WIRE OFF LO ORG/ WIRE PPL REAR DEFOGGER SYSTEM RECIRC CTRL IGNITION RECIRCULATION DOOR MOTOR (UNDER I/P ON HEATER- A/C CASE) RED WIRE TAN WIRE UNDERHOOD FUSE-RELAY CENTER WHT WIRE YEL WIRE

4 WHEEL DRIVE LOW (UNDER RIGHT END OF I/P) SIGNAL AUTOMATIC TRANSMISSION ONLY BLK WIRE BRN WIRE CONVENIENCE CENTER (UNDER LEFT SIDE OF I/P) DK BLU WIRE DK GRN WIRE FRONT AXLE ACTUATOR SOLENOID (RIGHT SIDE OF FRONT DRIVE AXLE) FRONT AXLE SOLENOID SWITCH (RIGHT REAR SIDE OF FRONT DRIVE AXLE) FUSE GRY WIRE HOT IN RUN I/P FUSE BLOCK INDICATOR LAMP INSTRUMENT CLUSTER LT BLU WIRE PANEL DIMMER SWITCH (ASSEMBLY) PANEL LPS FUSE PICKUP PNK/WHT WIRE POWERTRAIN CONTROL MODULE PPL PPL PPL RED WIRE RWAL DIODE MODULE (UNDER LEFT SIDE OF I/P) TRANSFER CASE MODE SELECTOR ILLUMINATION LAMP (AT TRANSFER CASE SELECTOR LEVER) TRANSFER CASE RELAY (RIGHT REAR OF ENG COMPT, NEAR BATTERY JUNCTION BLOCK) TRANSFER CASE SWITCH (LEFT TOP OF TRANSFER CASE) TRANSFER CASE SYNCRONIZER

AUDIO ALARM MODULE (ON CONVENIENCE CENTER) BLK WIRE BLK/WHT WIRE DIESEL GAS GAUGES FUSE 4 GRY WIRE HOT AT ALL TIMES HOT IN PARK OR HEADLIGHT HOT IN RUN, BULB TEST OR START I/P FUSE BLOCK (UNDER LEFT SIDE OF DASH) ILLUM FUSE 14 INSTRU- MENT CLUSTER SAFETY BELTS INDICATOR KEY-IN WARNING BUZZER SWITCH LEFT DOOR JAMB SWITCH LIGHTS ON INPUT POWER INPUT KEY-IN WARNING LT GRN WIRE ORG/ WIRE PNK IGNITION ON INPUT WIRE PNK WIRE SEAT BELT INPUT GROUND FASTEN BELTS OUT SEAT BELT SWITCH (IN DRIVER'S SAFETY BELT BUCKLE) STOP/HAZ FUSE 1 SUPPLEMENTAL RESTRAINTS SYSTEM TAN WIRE YEL WIRE

1222 1224 1225 1226 PNK WIRE 2-3 SHIFT SOL CTRL FUEL INJ CTRL EGR SOL CTRL ENG SHUT-OFF CTRL 4 WHEEL DRIVE LOW SWITCH 983 474 PPL 999 998 961 452 PPL ACCELERATOR PEDAL POSITION (APP) MODULE (TOP OF ACCELERATOR BRACKET) ANTI-LOCK BRAKES SYSTEM APP 1 SENSOR ENGINE COOLANT TEMPERATURE (ECT) SENSOR (RIGHT SIDE OF ENGINE) APP 2 SENSOR APP 3 SENSOR B/H BATTERY FEED FWD LOW SW BLK WIRE BLK/WHT WIRE BLK/YEL WIRE BLU/WHT WIRE BRN WIRE BRN/WHT WIRE CRANK FUSE TRANS FUSE CRUISE CONTROL SYSTEM CRUISE ON/OFF SIG DATA LINK CONNECTOR (UNDER LEFT SIDE OF I/P) DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE ECM-B FUSE ELECTRONIC 4-SPEED AUTOMATIC OVERDRIVE TRANSMISSION ENGINE SHUT- OFF SOLENOID (TOP FRONT OF ENGINE) FUEL INJ CTRL FUEL SOL FUSE FUEL SOLENOID (TOP FRONT OF ENGINE) FUEL SOLENOID DRIVER (TOP FRONT OF ENGINE) FUSE FUSE BLOCK GRY WIRE GRY/BLK WIRE GRY/RED WIRE HOT AT ALL TIMES HOT IN CRANK HOT IN RUN HOT IN START OR RUN LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE OPTICAL SENSOR AND FUEL TEMPER- ATURE SENSOR (TOP FRONT OF ENGINE) ORG/ WIRE ORG/BLK WIRE PNK WIRE POWERTRAIN CONTROL MODULE (PCM) (UNDER RIGHT END OF I/P) PPL PPL 15 16 PPL/WHT WIRE PRESSURE CONTROL SOL RANGE MODE SELECTOR RED WIRE RED/BLK WIRE RESUME/ACCEL SIG SET/COAST SIG SPEED SENSOR (LEFT REAR SIDE OF TRANSMISSION) SYSTEM GND CLOSURE SIG APP 2 SENS GND APP 1 SENS GND APP 3 SENS GND SENSOR GND TAN WIRE TAN/WHT WIRE TCC BRAKE SW TCC SOL 2-3 SHIFT SOL 1-2 SHIFT SOL TRANS FLUID TEMP (TFT) SENSOR TRANS INPUT SPD SIG CKP SIG OPTICAL SENS GND OPTICAL SENS CAM SIG TRANS OUTPUT TRANSMISSION INPUT SPEED SENSOR VEHICLE SPEED SENSOR BUFFER (UNDER RIGHT END OF I/P) VIN P ONLY VSS VSS HI RESOLUTION SIG VSS INPUT VSS OUTPUT WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

A/C SIG AIR CONDITIONING SYSTEM APP 3 SENS SIG FUEL TEMP SIG IAT SIG B/H BARO SENSOR (VIN F) (UPPER LEFT SIDE OF COWL) BLK WIRE BLK/WHT WIRE BLU WIRE BLU/WHT WIRE BRN WIRE BRN/WHT WIRE DK BLU WIRE DK GRN WIRE ECM I FUSE EGR CONTROL PRESSURE/ BARO SENSOR (VIN P, S) (UPPER LEFT SIDE OF COWL) ENG-I FUSE FUEL HEATER (TOP REAR OF ENGINE) FUEL PUMP OIL PRESSURE SWITCH FUEL PUMP RELAY (RIGHT UPPER COWL) FUEL PUMP/SENDER (IN FUEL TANK) FUSE BLOCK FUSIBLE LINK FUSIBLE LINKS GAUGES FUSE GLOW PLUG CONTROL RELAY (RIGHT REAR TOP OF ENGINE) GLOW PLUG SIG GRY WIRE GRY/BLK WIRE HOT AT ALL TIMES HOT AT ALL TIMES STOP FUSE HOT IN RUN BRAKE FUSE HOT IN RUN, BULB TEST OR START HOT IN START OR RUN GLOW PLUG FUSE IGNITION FEED INSTRUMENT CLUSTER INSTRUMENT CLUSTERS SYSTEM LEFT BANK GLOW PLUGS LT BLU/BLK WIRE LT GRN WIRE MANIFOLD ABSOLUTE PRESSURE SENSOR (TURBO ONLY) (LEFT REAR ENGINE COMPT, AT COWL) ORG/ WIRE ORG/BLK WIRE PNK/BLK WIRE POWERTRAIN CONTROL MODULE (PCM) (UNDER RIGHT END OF I/P) PPL PPL 15 16 PPL/WHT WIRE RED WIRE RED/BLK WIRE RIGHT BANK GLOW PLUGS SERVICE ENGINE SOON LAMP TAN WIRE TAN/BLK WIRE TCC/ BRAKE SWITCH (ON BRAKE PEDAL SUPPORT BRACKET) VIN P ONLY WAIT LAMP "SERVICE THROTTLE" LAMP WASTEGATE SOL CTRL EGR VENT SOL CTRL "SERVICE THROTTLE" LAMP WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

4 WHEEL DRIVE LOW SWITCH 983 474 PPL 999 998 961 452 PPL ACCELERATOR PEDAL POSITION (APP) MODULE (TOP OF ACCELERATOR BRACKET) ANTI-LOCK BRAKES SYSTEM APP 1 SENSOR APP 2 SENSOR APP 3 SENSOR BATTERY FEED BLK WIRE BLK/WHT WIRE BLK/YEL WIRE BLU/WHT WIRE BOOST SIG ECT SIG TRANS FLUID TEMP SIG BRN WIRE BRN/WHT WIRE CKP SIG OPTICAL SENS GND OPTICAL SENS CAM SIG CLUTCH PEDAL POSITION SWITCH CONVEN- IENCE CENTER CRANK FUSE CRUISE CONTROL SYSTEM CRUISE ON/OFF SIG DATA LINK CONNECTOR (UNDER LEFT SIDE OF I/P) DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE ECM-B FUSE ENGINE COOLANT TEMPERATURE (ECT) SENSOR (RIGHT SIDE OF ENGINE) ENGINE SHUT- OFF SOLENOID (TOP FRONT OF ENGINE) FUEL INJ CTRL FUEL INJ CTRL EGR SOL CTRL ENG SHUT-OFF CTRL FUEL SOL FUSE FUEL SOLENOID (TOP FRONT OF ENGINE) FUEL SOLENOID DRIVER (TOP FRONT OF ENGINE) FUSE FUSE BLOCK GLOW PLUG RLY CTRL SERIAL DATA TRANS OUTPUT SPD SIG GRY WIRE GRY/BLK WIRE HOT AT ALL TIMES HOT IN CRANK HOT IN RUN HOT IN START OR RUN LT BLU WIRE LT GRN WIRE LT GRN/BLK WIRE OPTICAL/ FUEL TEMP SENSOR (TOP FRONT OF ENGINE) ORG/ WIRE ORG/BLK WIRE PNK WIRE PNK/WHT WIRE POWERTRAIN CONTROL MODULE (PCM) (UNDER RIGHT END OF I/P) PPL PPL 15 16 PPL/WHT WIRE RED WIRE RESUME/ACCEL SIG SET/COAST SIG SPEED SENSOR (LEFT REAR SIDE OF TRANSMISSION) SYSTEM GND CLOSURE GND APP 2 SENS GND APP 1 SENS GND APP 3 SENS GND SENSOR GND SYSTEM GND FUEL INJ SIG APP SENS 2 SIG APP SENS 1 SIG EGR CTRL/BARO SIG TAN WIRE TAN/WHT WIRE TCC BRAKE SW TRANS OUTPUT VEHICLE SPEED SENSOR BUFFER (UNDER RIGHT END OF I/P) VSS VSS HI RESOLUTION SIG VSS INPUT VSS OUTPUT WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE