GMC Pickup C2500 (1985-2000) red Wiring diagrams

A/C COMP FUSE AUX FAN CTRL AUX FAN FUSE AUXILIARY COOLING FAN MOTOR AUXILIARY COOLING FAN RELAY (IN UNDERHOOD FUSE/RELAY CENTER) BLK WIRE DK BLU WIRE DK GRN WIRE FAN REQ HEATER AND A/C CONTROL MODULE HOT AT ALL TIMES HOT IN RUN OR START ORG/ WIRE RECIRCULATION DOOR MOTOR (ON A/C- HEATER HOUSING) RED WIRE RELAY CTRL UNDERHOOD FUSE-RELAY CENTER VEHICLE CONTROL MODULE (LEFT REAR OF ENGINE COMPT)

A/C COMP FUSE AUX FAN CTRL AUX FAN FUSE AUXILIARY COOLING FAN MOTOR AUXILIARY COOLING FAN RELAY (IN UNDERHOOD FUSE/RELAY CENTER) BLK WIRE DK BLU WIRE DK GRN WIRE FAN REQ HEATER AND A/C CONTROL MODULE HOT AT ALL TIMES HOT IN RUN OR START ORG/ WIRE RECIRCULATION DOOR MOTOR (ON A/C- HEATER HOUSING) RED WIRE RELAY CTRL UNDERHOOD FUSE-RELAY CENTER VEHICLE CONTROL MODULE (LEFT REAR OF ENGINE COMPT)

1 2 3 4 5 6 7 8 9 10 ILLUMINATION GROUND A/C DISABLE AUX FAN CTRL IGNITION A/C COMP FUSE A/C COMPRESSOR CLUTCH A/C COMPRESSOR CLUTCH RELAY (IN UNDERHOOD FUSE/RELAY CENTER) A/C COMPRESSOR CYCLING SWITCH (IN LOW PRESSURE LINE, ON ACCUMULATOR) A/C CTRL A/C ENABLE A/C HIGH PRESSURE CUTOUT SWITCH (ON A/C COMPRESSOR) A/C LOW PRESSURE CUTOUT SWITCH (ON A/C COMPRESSOR) AIR TEMP DR SENSOR MODE SIGNAL A/C SWITCH BATTERY IGNITION GROUND DEFOGGER ELEMENT BLK WIRE BLOWER FUSE 3 BLOWER MOTOR BLOWER RESISTOR (UNDER RIGHT SIDE OF DASH, ON HEATER HOUSING) BLOWER SWITCH BRN WIRE DIODE DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE FRONT MODE DOOR MOTOR (UNDER DASH ON HEATER- A/C CASE) FUSE BLOCK GRY WIRE HEATER AND A/C CONTROL MODULE HIGH BLOWER RELAY (UNDER DASH ON TOP OF HEATER-A/C CASE) HOT AT ALL TIMES UNDERHOOD FUSE-RELAY CENTER HOT IN RUN HOT IN RUN OR START HTR A/C FUSE 12 IGN 1 FUSE LT BLU WIRE LT GRN WIRE OFF LO ORG/ WIRE PNK WIRE POWERTRAIN CONTROL MODULE (LEFT REAR OF ENGINE COMPT) PPL REAR DEFOGGER SYSTEM RED WIRE TAN WIRE WHT WIRE YEL WIRE

1 2 3 4 5 6 7 8 9 10 ILLUMINATION GROUND A/C DISABLE AUX FAN CTRL IGNITION A/C COMP FUSE A/C COMPRESSOR CLUTCH A/C COMPRESSOR CLUTCH RELAY (IN UNDERHOOD FUSE/RELAY CENTER) A/C COMPRESSOR CYCLING SWITCH (IN LOW PRESSURE LINE, ON ACCUMULATOR) A/C CTRL A/C ENABLE A/C HIGH PRESSURE CUTOUT SWITCH (ON A/C COMPRESSOR) A/C LOW PRESSURE CUTOUT SWITCH (ON A/C COMPRESSOR) AIR TEMP DR SENSOR MODE SIGNAL A/C SWITCH BATTERY IGNITION GROUND DEFOGGER ELEMENT BLK WIRE BLOWER FUSE 3 BLOWER MOTOR BLOWER RESISTOR (UNDER RIGHT SIDE OF DASH, ON HEATER HOUSING) BLOWER SWITCH BRN WIRE DIODE DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE FRONT MODE DOOR MOTOR (UNDER DASH ON HEATER- A/C CASE) FUSE BLOCK GRY WIRE HEATER AND A/C CONTROL MODULE HIGH BLOWER RELAY (UNDER DASH ON TOP OF HEATER-A/C CASE) HOT AT ALL TIMES UNDERHOOD FUSE-RELAY CENTER HOT IN RUN HOT IN RUN OR START HTR A/C FUSE 12 IGN 1 FUSE LT BLU WIRE LT GRN WIRE OFF LO ORG/ WIRE PNK WIRE POWERTRAIN CONTROL MODULE (LEFT REAR OF ENGINE COMPT) PPL REAR DEFOGGER SYSTEM RED WIRE TAN WIRE WHT WIRE YEL WIRE

ABS FUSE ABS IND. BATTERY PUMP MOTOR GROUND BLK WIRE BLK/WHT WIRE BRAKE FUSE 18 BRAKE IND BRAKE PRESSURE WARNING SWITCH (UNDERSIDE OF EBCM) BRAKE SW OUTPUT BRN WIRE DAYTIME RUNNING LAMP (DRL) MODULE (BEHIND LEFT SIDE OF DASH) DK GRN WIRE ELECTRONIC BRAKE CONTROL MODULE (LEFT SIDE OF ENGINE COMPT) ENGINE CONTROLS SYSTEM FRONT AXLE ACTUATOR (ON RIGHT REAR OF FRONT DRIVE AXLE) FUSE/RELAY BLOCK (LEFT REAR OF ENGINE COMPT) GAUGES FUSE 4 HOT AT ALL TIMES HOT IN RUN HOT IN RUN OR START I/P FUSE BLOCK (UNDER LEFT SIDE OF DASH) IGNITION ABS IND GROUND BRAKE SW INPUT INSTRUMENT CLUSTER LEFT FRONT WHEEL SPEED SENSOR LT BLU WIRE LT GRN WIRE LT GRN/BLK WIRE M/T NEAR BREAKOUT TO TRANSFER CASE RELAY) PNK WIRE PPL PPL DATA LINK CONNECTOR (DLC) (LEFT OF STEERING COLUMN) PPL PPL 1807 680 PPL SERIAL DATA PPL/WHT WIRE RED WIRE RIGHT FRONT WHEEL SPEED SENSOR SENSOR LOW SENSOR LOW SENSOR HIGH SENSOR HIGH 830 872 STOPLAMP SWITCH (TOP OF BRAKE PEDAL) TAN WIRE TAN/WHT WIRE TRANSFER CASE CONTROL MODULE (ON STEERING COLUMN SUPPORT BRACKET) TRANSMISSIONS SYSTEM VEHICLE CONTROL MODULE (VCM) (LEFT SIDE OF ENGINE COMPT) VEHICLE SPEED SENSOR (VSS) (LEFT SIDE OF TRANSMISSION/ TRANSFER CASE) VEHICLE SPEED SIG VSS VSS SIG BRAKE LAMP IND OUT SERIAL DATA LINE BRAKE IND INPUT EBCM GROUND YEL WIRE YEL/BLK WIRE

1134 1134 39 10 10 PARK BRAKE SIG IND BULB CHK IGNITION LAMP FEED PNK WIRE 33 33 BRAKE IND CTRL BRAKE WARN IN 592 592 150 DRL RELAY CTRL BLK WIRE BLK/WHT WIRE BRN WIRE BULB TEST CONVENIENCE CENTER (UNDER LEFT SIDE OF DASH) DAYTIME RUNNING LAMP MODULE (BEHIND LEFT SIDE OF DASH) DAYTIME RUNNING LAMPS RELAY DIODE 203 DRL INDICATOR DRL-FOG FUSE 15 FOG LAMP RELAY FOG LAMP SWITCH GAUGES FUSE 4 GRN WIRE GROUND GRY WIRE HEAD OFF PARK HEAD- LAMP DIMMER SWITCH HEADLAMP, PANEL DIMMER SWITCH HIGH BEAM INDICATOR HOT AT ALL TIMES HOT IN RUN, BULB TEST OR START I/P FUSE BLOCK (LEFT SIDE OF DASH, IGNITION SWITCH ILLUM LAMP INSTRUMENT CLUSTER INSTRUMENT CLUSTER SYSTEM (BRAKE WARNING INDICATOR) LEFT FOG LAMP LEFT HEAD- LAMP RIGHT HEAD- LAMP LIGHTING FUSE 8 LOCK OFF LT BLU WIRE LT GRN WIRE LT GRN/BLK WIRE NCA WIRE OFF ON INDICATOR ORG/ WIRE PARK BRAKE WARNING SWITCH PK LPS FUSE 9 PNK WIRE PPL RED WIRE RIGHT FOG LAMP RUN WIRE TAN WIRE TAN/WHT WIRE UNDERHOOD FUSE BLOCK (LEFT REAR OF ENGINE COMPT) W/ FOG LAMPS WHT WIRE YEL WIRE

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

1-2 SHIFT SOL LT 2-3 SHIFT SOLENOID AIR INJECTION REACTION PUMP CLUTCH (ON FRONT OF AIR PUMP) AIR INJECTION REACTION RELAY (UNDERHOOD FUSE/ RELAY CENTER) AUTOMATIC TRANSMISSION AUTOMATIC TRANSMISSION FLUID PRESSURE (TFP) MANUAL VALVE POSITION SWITCH BLK WIRE BLK/WHT WIRE BLU WIRE BRN WIRE DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE EXHAUST GAS RECIRCULATION (EGR) VALVE (ON TOP LEFT SIDE OF ENG) FLUID TEMPERATURE SENSOR 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 IN RUN, START 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 PNK 1 2 3 4 5 WIRE PNK PNK PNK PNK 3 4 5 6 WIRE PNK PNK PNK PNK PNK WIRE PNK PNK WIRE PNK PPL WIRE PNK WIRE PNK/BLK WIRE PPL PPL LT PPL/WHT WIRE PRESSURE CONTROL SOLENOID VALVE RED WIRE RED/BLK WIRE TAN WIRE TORQUE CONVERTOR CLUTCH PULSE WIDTH MODULATION SOLENOID UNDERHOOD FUSE/RELAY CENTER WHT WIRE YEL WIRE YEL/BLK WIRE

16 PPL AUTOMATIC TRANSMISSION INPUT SHAFT SPEED SENSOR (LEFT SIDE OF TRANSMISSION) AUX TANK FUEL LVL SIG AUXILIARY FUEL TANK LEVEL SENSOR (IN FUEL TANK) BALANCE FUEL PUMP (ON INSIDE LEFT FRAME RAIL NEAR FRONT OF REAR TANK) 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 INPUT FUEL PUMP BALANCE MODULE (INSIDE LEFT SIDE OF FRAME RAIL) FUEL PUMP BALANCE RELAY (ON FUEL PUMP BALANCE MODULE) FUEL PUMP MODULE (W/ DUAL FUEL TANKS) FUEL PUMP, SENDER (W/O DUAL FUEL TANKS) (IN FUEL TANK) FUEL TANK PRESSURE SENSOR (IN FUEL TANK) (CALIFORNIA) GAUGES FUSE 4 GRN WIRE GROUND GRY WIRE HOT IN OFF, RUN OR START HOT IN RUN OR START HOT IN RUN OR START UNDERHOOD FUSE/RELAY CENTER I/P FUSE BLOCK IGN E FUSE INPUT INSTRUMENT CLUSTER INTAKE AIR TEMPERATURE SENSOR (IN AIR INTAKE DUCT) LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR (TOP RIGHT FRONT OF ENGINE) MASS AIR FLOW SENSOR (IN AIR INTAKE DUCT) OUTPUT TO GAUGE PNK IGNITION WIRE PNK PNK PNK WIRE PNK WIRE PPL PPL/WHT WIRE PRIMARY TANK FUEL LVL SIG RED WIRE RED/BLK WIRE RELAY CTRL SERVICE ENGINE SOON INDICATOR SPEEDOMETER TACHOMETER TAN WIRE THROTTLE POSITION SENSOR (ON THROTTLE BODY ASSEMBLY) TRANS FUSE 20 W/ DUAL FUEL TANKS W/O DUAL FUEL TANK W/O DUAL FUEL TANK W/ DUAL FUEL TANKS W/O DUAL FUEL TANKS W/ DUAL FUEL TANK WHT (OR WIRE WHT WIRE YEL WIRE YEL/BLK WIRE

A/C REQUEST SIGNAL A/T AIR CONDITIONING SYSTEM AIR INLET VLV MTR CTLR 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 A/T 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 BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE EGR VLV FEED 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 FUEL PUMP RLY CTRL 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 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 BRAKE INPUT INPUT SW INPUT IGNITION COIL IGNITION CONTROL MODULE (ON REAR OF INTAKE MANIFOLD) IGNITION FEED IGN TIMING SIG. IGN COIL OUT IGNITION PRESSURE SWITCH INPUT PRESSURE SWITCH INPUT LT BLU/BLK WIRE LT BLU/WHT WIRE LT VSS SERIAL INPUT DATA SIG MANUAL OR AUTOMATIC ORG/ 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 SPEED SENSOR SPEED STOPLAMP/ VCM SENSOR CLUTCH SIG INPUT SWITCH INPUT STOPLAMP SWITCH (TOP OF BRAKE PEDAL) SWITCH SIGNAL TRANSFER CASE CONTROL MODULE (UNDER DASH ON STEERING COLUMN SUPPORT BRACKET) UNDERHOOD FUSE-RELAY CENTER VEHICLE CONTROL MODULE (VCM) (LEFT SIDE OF ENGINE COMPT) VSS SIG OUT VSS SIG OUT CHECK ENG LP CTRL 389 419 WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE