GMC Pickup C2500 (1985-2000) red Wiring diagrams

1-2 SHIFT SOLENOID 2-3 SHIFT SOLENOID 29 30 VSS LO (GROUND) VSS HI (SIGNAL) ANTI-LOCK BRAKES SYSTEM AUTOMATIC TRANSMISSION BLK WIRE BLK/WHT WIRE BLU/WHT WIRE BRAKE FUSE 18 BRN WIRE BRN/WHT WIRE CRUISE CONTROL DK BLU WIRE ECM 1 FUSE ECM-B FUSE ELECTRONIC BRAKE CONTROL MODULE ENGINE CONTROLS ENGINE COOLANT TEMPERATURE SENSOR (TOP RIGHT FRONT OF ENGINE) FLUID TEMP SENSOR FRONT WHEEL LOCK FUEL INJECTORS, IGNITION CONTROL MOUDULE, IGNITION COIL FUEL PUMP, OIL PRESS SWITCH/ SENDER, FUEL PUMP RELAY GRY WIRE GRY/BLK WIRE HI LO HOT AT ALL TIMES HOT IN HOT IN OFF, RUN OR START HOT IN RUN OR START HOT IN RUN OR START I/P FUSE BLOCK (UNDER LEFT SIDE OF DSAH) GAUGES FUSE 4 I/P FUSE BLOCK (UNDER LEFT SIDE OF DASH) INLINE GENDER ADAPTOR INSTRUMENT CLUSTER LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE MALFUNCTION INDICATOR LAMP ORG/ WIRE PNK PNK WIRE PNK WIRE PPL PPL DATA LINK CONNECTOR (UNDER LEFT SIDE OF DASH) PPL/WHT WIRE PRESS CTRL SOLENOID RED WIRE RED/BLK WIRE REV, LO RUN WIRE TAN WIRE TCC PWM SOLENOID TCC/ABS/ CRUISE SWITCH THROTTLE POSITION SENSOR (MOUNTED TO SIDE OF THROTTLE BODY) TRANS FUSE 20 TRANS RANGE PRESSURE SWITCH ASSEMBLY TRANSFER CASE CIRCUIT TRANSFER CASE, AXLE SWITCHES UNDERHOOD FUSE/RELAY CENTER (LEFT REAR OF ENGINE COMPT) VEHICLE CONTROL MODULE (LEFT SIDE OF ENGINE COMPT) VEHICLE SPEED SENSOR (LEFT SIDE OF YEL WIRE YEL/BLK WIRE

ALL OTHERS BATTERY BLK (OR RED) WIRE BLK WIRE BRN WIRE CHARGE WARNING INDICATOR FUSIBLE LINK GAUGES FUSE 4 GENERATOR HOT IN RUN, START I/P FUSE BLOCK (UNDER LEFT SIDE OF DASH) INSTRUMENT CLUSTER MEGA FUSE BLOCK (ON RIGHT FRONT OF ENGINE COMPARTMENT, NEAR BATTERY) PNK 22 WIRE POWER DISTRIBUTION SYSTEM RED WIRE UPLEVEL/ ENHANCED

1-2 SHIFT SOLENOID 2-3 SHIFT SOLENOID A/T ISS SENSOR VSS IN SENSOR GROUND SENSOR GROUND APP 1 SIGNAL IN ACCELERATOR PEDAL POSITION MODULE (PART OF ACCELERATOR PEDAL) APP 3 SIGNAL IN SENSOR GROUND A/T ISS SENS LO AUTOMATIC TRANSMISSION BLK WIRE BLK/WHT WIRE BLU/WHT WIRE BRAKE FUSE 18 BRN WIRE BRN/WHT WIRE DK BLU WIRE DK GRN WIRE ECM-B FUSE ELECTRONIC BRAKE CONTROL MODULE PPL ENGINE CONTROLS SYSTEM ENGINE SHUTOFF SOLENOID, FUEL SOLENOID EXTERIOR LIGHTS FUEL PUMP, OIL PRESS SWITCH/ SENDER, FUEL PUMP RELAY GAUGES FUSE 4 GRY WIRE GRY/BLK WIRE HI LO HOT AT ALL TIMES HOT IN HOT IN RUN OR START I/P FUSE BLOCK (UNDER LEFT SIDE OF DASH) INLINE GENDER ADAPTOR INSTRUMENT CLUSTER LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE MALFUNCTION INDICATOR LAMP ORG/ WIRE PNK PPL WIRE PNK WIRE POWERTRAIN CONTROL MODULE (RIGHT SIDE OF DASH NEAR BLOWER MOTOR) PPL PPL DATA LINK CONNECTOR (UNDER LEFT SIDE OF DASH) PPL PNK PNK WIRE PPL PRESS CTRL SOLENOID PPL/WHT WIRE RED WIRE RED/BLK WIRE RUN WIRE STOP/HAZ FUSE 1 TAN WIRE TAN/WHT WIRE TCC PWM SOLENOID TRANS FLUID TEMP SENSOR TRANS FUSE 20 TRANS RANGE PNK PNK REV, LO WIRE TRANS RANGE PRESSURE SWITCH ASSEMBLY TRANSFER CASE CIRCUIT TRANSFER CASE CIRCUIT PNK WIRE TURN/ HAZARD SWITCH, CHIME MODULE VEHICLE SPEED SENSOR (LEFT SIDE OF VEHICLE SPEED SENSOR BUFFER (RIGHT SIDE OF DASH) WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

1-2 SHIFT SOLENOID 2-3 SHIFT SOLENOID 29 30 VSS LO (GROUND) VSS HI (SIGNAL) ANTI-LOCK BRAKES SYSTEM AUTOMATIC TRANSMISSION BLK WIRE BLK/WHT WIRE BLU/WHT WIRE BRAKE FUSE 18 BRN WIRE BRN/WHT WIRE CRUISE CONTROL DK BLU WIRE ECM 1 FUSE ECM-B FUSE ELECTRONIC BRAKE CONTROL MODULE ENGINE CONTROLS ENGINE COOLANT TEMPERATURE SENSOR (TOP RIGHT FRONT OF ENGINE) FLUID TEMP SENSOR FRONT WHEEL LOCK FUEL INJECTORS, IGNITION CONTROL MOUDULE, IGNITION COIL FUEL PUMP, OIL PRESS SWITCH/ SENDER, FUEL PUMP RELAY GRY WIRE GRY/BLK WIRE HI LO HOT AT ALL TIMES HOT IN HOT IN OFF, RUN OR START HOT IN RUN OR START HOT IN RUN OR START I/P FUSE BLOCK (UNDER LEFT SIDE OF DSAH) GAUGES FUSE 4 I/P FUSE BLOCK (UNDER LEFT SIDE OF DASH) INLINE GENDER ADAPTOR INSTRUMENT CLUSTER LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE MALFUNCTION INDICATOR LAMP ORG/ WIRE PNK PNK WIRE PNK WIRE PPL PPL DATA LINK CONNECTOR (UNDER LEFT SIDE OF DASH) PPL/WHT WIRE PRESS CTRL SOLENOID RED WIRE RED/BLK WIRE REV, LO RUN WIRE TAN WIRE TCC PWM SOLENOID TCC/ABS/ CRUISE SWITCH THROTTLE POSITION SENSOR (MOUNTED TO SIDE OF THROTTLE BODY) TRANS FUSE 20 TRANS RANGE PRESSURE SWITCH ASSEMBLY TRANSFER CASE CIRCUIT TRANSFER CASE, AXLE SWITCHES UNDERHOOD FUSE/RELAY CENTER (LEFT REAR OF ENGINE COMPT) VEHICLE CONTROL MODULE (LEFT SIDE OF ENGINE COMPT) VEHICLE SPEED SENSOR (LEFT SIDE OF YEL WIRE YEL/BLK WIRE

BLK/WHT WIRE BRN WIRE CAPACITOR DK GRN/WHT WIRE ELECTRONIC POWER STEERING SYSTEM SECURITY INDICATOR ENGINE CONTROLS SYSTEM EVO SOL FD EVO SOL OUT EVO/PASSLOCK MODULE (UNDER CENTER OF DASH) FILTER (MOLDED IN STEERING COLUMN HARNESS) GAUGES FUSE 4 GRY WIRE HOT AT ALL TIMES HOT IN RUN OR START I/P FUSE BLOCK INSTRUMENT CLUSTER LT BLU WIRE NCA WIRE ORG/ WIRE ORG/BLK WIRE PASSLOCK SENSOR (INTERNAL TO STEERING COLUMN) PASSLOCK SENSOR REF SIGNAL GRD PNK PPL WIRE PNK WIRE PPL DATA LINK CONNECTOR (UNDER LEFT SIDE OF DASH) RED WIRE RED/WHT WIRE RESISTOR 10 OHMS SECURITY FUSE 21 STEERING HANDWHEEL SPEED SENSOR (SENSOR GROUND) WHT WIRE YEL WIRE

1-2 SHIFT SOL LT 16 17 18 PPL 2-3 SHIFT SOLENOID 3-2 SHIFT SOLENOID AIR INJECTION REACTION PUMP MOTOR (LEFT FRONT OF ENG COMPT) AIR INJECTION REACTION PUMP RELAY (CALIFORNIA) (UNDERHOOD FUSE/ RELAY CENTER) AUTOMATIC TRANSMISSION AUTOMATIC TRANSMISSION FLUID PRESSURE (TFP) MANUAL VALVE POSITION SWITCH AUX-B FUSE BLK WIRE BLK/WHT WIRE BLU WIRE BRN WIRE BRN/WHT WIRE DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE EVAPORATIVE EMISSIONS (EVAP) CANISTER VENT VALVE (LEFT SIDE OF ENGINE COMPT) EXHAUST GAS RECIRCULATION (EGR) VALVE (FRONT OF ENGINE NEAR THERMOSTAT HOUSING) FUEL INJ 1 FUEL INJ 2 FUEL INJ 3 FUEL INJ 4 FUEL INJ 5 FUEL INJ 6 FUEL INJ 7 FUSE GRN WIRE GRY WIRE HOT AT ALL TIMES HOT IN RUN, START HOT IN RUN, START UNDER HOOD FUSE/RELAY CENTER LT BLU WIRE LT BLU/BLK WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE LT PNK WIRE NCA WIRE ORG/ WIRE PNK FUEL INJ 8 WIRE PNK PNK 1 2 3 4 5 6 7 8 WIRE PNK PNK PNK 3 4 5 6 7 8 9 10 11 12 13 14 WIRE PNK PNK PNK PNK PNK WIRE PNK PNK PNK PNK WIRE PNK PNK WIRE PNK WIRE PNK/BLK WIRE PPL PPL LT PPL PNK WIRE PPL/WHT WIRE PRESSURE CONTROL SOLENOID VALVE RED WIRE RED/BLK WIRE SOLENOID CHECK VALVE TAN WIRE TAN/BLK WIRE TAN/WHT WIRE TCC SOLENOID TORQUE CONVERTER CLUTCH PULSE WIDTH MODULATION SOLENOID TRANS FLUID TEMPERATURE SENSOR WHT WIRE YEL WIRE YEL/BLK WIRE

16 17 18 PPL 39 40 41 PPL ACTUAL GAS AF ECU BAT AF ECU GND AF ECU IGN ALTERNATIVE FUEL ENGINE CONTROL UNIT (LEFT SIDE OF ENGINE COMPT) BLK WIRE BRN WIRE BRN/WHT WIRE CLASS 2 DATA CNG FUSE DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE ECT INPUT EGR SENS F PMP RLY FPS SIG FPS/FTS GND FTS SIG FUEL LEV OUT FUEL PRESSURE SENSOR (END OF CNG FUEL TANK) FUEL TEMPERATURE SENSOR (END OF CNG FUEL TANK) GAS FLOW OUT GAUGE SEL SW GRY WIRE HI PRES LO HOT AT ALL TIMES UNDER HOOD FUSE/RELAY CENTER HOT IN RUN, BULB TEST AND START IAT INPUT IGN E FUSE IND CTRL LOW PRES LO LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE MAF INPUT MAP INPUT MIL CTRL MIL OUT NGO ENABLE ORG/ WIRE PNK 2 3 4 5 6 7 WIRE PNK 24 25 26 27 28 29 30 31 32 33 34 35 36 37 WIRE PNK PNK PNK 3 4 5 6 7 8 9 10 11 12 13 14 WIRE PNK PNK PNK 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 WIRE PNK WIRE PPL PPL/WHT WIRE RED WIRE RED/BLK WIRE RELAY CTRL SENSOR GND SERIAL DATA TAN WIRE TAN/WHT WIRE TP SENSOR VSS INPUT WHT WIRE YEL WIRE YEL/BLK WIRE

32 33 PPL 39 40 41 PPL AF FUEL PUMP RELAY (LEFT OF ENGINE COMPT) BLK WIRE BRN WIRE BRN/WHT WIRE DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE FUEL GAUGE RELAY (LEFT OF ENGINE COMPT) FUEL GAUGE SELECT SWITCH GAS MASS SENSOR (RIGHT FRONT OF ENGINE) GRY WIRE GRY/BLK WIRE HIGH PRESSURE LOCK-OFF SOLENOID (END OF CNG FUEL TANK) IGNITION RELAY (LEFT OF ENGINE COMPT) LOCK-OFF RELAY (LEFT OF ENGINE COMPT) LOW PRESSURE LOCK-OFF SOLENOID (RIGHT MIDDLE OF ENGINE) LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE MIXTURE CONTROL VALVE MOTOR (RIGHT FRONT OF ENGINE) NCA WIRE ORG/ WIRE PNK 2 3 4 5 6 7 WIRE PNK 24 25 26 27 28 29 30 31 32 33 34 35 36 37 WIRE PNK PNK PNK 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 WIRE PNK PNK PNK WIRE PNK WIRE PPL PPL/WHT WIRE RED WIRE RED/BLK WIRE TAN WIRE TAN/WHT WIRE WHT WIRE YEL WIRE YEL/BLK WIRE

16 PPL 32 33 PPL AUTOMATIC TRANSMISSION INPUT SHAFT SPEED SENSOR (LEFT SIDE OF TRANSMISSION) BLK WIRE BLK/WHT WIRE BLU WIRE BLU/WHT WIRE BRN WIRE BRN/WHT WIRE CONVENIENCE CENTER (UNDER LEFT SIDE OF DASH) DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE FUEL GAUGE FUEL PUMP, SENDER (IN FUEL TANK) FUEL TANK PRESSURE SENSOR (IN FUEL TANK) GAUGES FUSE 4 GRN WIRE GRY WIRE GRY/BLK WIRE HOT IN OFF, RUN OR START HOT IN RUN OR START I/P FUSE BLOCK INPUT INSTRUMENT CLUSTER INTAKE AIR TEMPERATURE SENSOR (IN AIR INTAKE DUCT) LT BLU/WHT WIRE LT GRN WIRE M/T ONLY MASS AIRFLOW SENSOR (IN AIR INTAKE DUCT) PNK (TAILLAMP EXTENSION HARN, 6 CM FROM THE FUEL PUMP HARN BREAKOUT) WIRE PNK 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 WIRE PNK PNK PNK WIRE PNK WIRE PPL PPL/WHT WIRE RED WIRE RED/BLK WIRE SERVICE ENGINE SOON INDICATOR SIG IGN GRD PNK WIRE SPEEDOMETER TACHOMETER TAN WIRE TAN/BLK WIRE THROTTLE POSITION SENSOR (ON THROTTLE BODY ASSEMBLY) TRANS FUSE 20 UPSHIFT LAMP W/O DUAL FUEL TANK WHT WIRE YEL WIRE YEL/BLK WIRE

A/C REQUEST SIGNAL AIR CONDITIONING SYSTEM AIR INLET VLV MTR CTLR AUTOMATIC AUTOMATIC TRANSFER CASE SHIFT CONTROLLER BLK WIRE BLK/WHT WIRE BLU WIRE BLU/WHT WIRE BRAKE FUSE 18 BRN WIRE BRN/WHT WIRE CLUTCH PEDAL POSITION (CPP) SWITCH (AT TOP OF CLUTCH PEDAL BRACKET) CPP SW INPUT FOUR WHL DR SIG LO CRUISE CTRL SIG ENG 23 24 CRUISE CONTROL MODULE (LEFT REAR OF ENGINE COMPT, ON FIREWALL) DATA LINK CONNECTOR (UNDER LEFT SIDE OF DASH, LEFT SIDE OF STEERING COLUMN) DISTRIBUTOR DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE ELECTRONIC BRAKE CONTROL MODULE (EBCM) (ON LEFT SIDE OF ENGINE COMPT) ELECTRONIC VARIABLE ORIFICE/ PASSLOCK CONTROL MODULE (CENTER OF DASH) FORCE MOTOR FEED TRANS INPUT SPEED RTN TRANS INPUT SPEED SIG EST OUTPUT SIG FORCE MOTOR RETURN GROUND GROUND SENSOR GROUND FUEL LEVEL INPUT SWITCH SIGNAL FUEL PUMP PRIME CONNECTOR (LEFT REAR OF ENG COMPT) FUEL PUMP RELAY GRN WIRE GROUND GRY WIRE GRY/BLK WIRE HIGH VOLTAGE COIL WIRE HOT AT ALL TIMES UNDERHOOD FUSE- RELAY CENTER ECMB FUSE HOT IN RUN I/P FUSE BLOCK IGN INPUT BRAKE SW INPUT INPUT IGNITION IGNITION COIL (TOP RIGHT REAR OF ENGINE) IGNITION CONTROL MODULE (RIGHT SIDE REAR OF ENGINE) IGNITION FEED IGN TIMING SIG. IGN COIL OUT IGNITION PRESSURE SWITCH INPUT PRESSURE SWITCH INPUT LT BLU/BLK WIRE LT BLU/WHT WIRE LT DK VSS INPUT SERIAL DATA SIG MANUAL OR SELECTABLE ORG/ WIRE PNK 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 WIRE PNK IGNITION FOUR WHL DR SIG EGR VLV GROUND WIRE PNK PNK PNK WIRE PNK WIRE PPL PPL (OR PPL A/T M/T PPL PPL PPL PPL 420 OR PPL/WHT WIRE PRESSURE SWITCH INPUT RADIO RED WIRE RED/BLK WIRE SENSOR RETURN SHIFT IND LP OUT EGR VLV FEED SPEED SENSOR SPEED SENSOR INPUT STOPLAMP/ CLUTCH SWITCH INPUT VCM SIG STOPLAMP SWITCH (TOP OF BRAKE PEDAL) SWITCH SIGNAL TAN/BLK WIRE TRANSFER CASE CONTROL MODULE (UNDER DASH ON STEERING COLUMN SUPPORT BRACKET) TRANSFER CASE SWITCH (LEFT TOP OF TRANSFER CASE) TRANSMISSIONS SYSTEM UNDERHOOD FUSE-RELAY CENTER VEHICLE CONTROL MODULE (VCM) (LEFT SIDE OF ENGINE COMPT) WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE