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

3 22 SPEED SENSOR OUTPUT BLK WIRE BLK/WHT WIRE BLU WIRE BRAKE FUSE 18 BRN WIRE BRN/WHT WIRE CLUTCH PEDAL POSITION SWITCH (TOP OF CLUTCH PEDAL) CRUISE CONTROL MODULE (LEFT REAR OF ENGINE COMPARTMENT) CRUISE CONTROL SWITCH CRUISE ENGAGE INPUT CRUISE FUSE 6 CRUISE ON INPUT SET/COAST SIG RESUME/ACCEL SIG DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE ENGINE CONTROL SYSTEM EXTERIOR LIGHT SYSTEM GRY WIRE GRY/BLK WIRE HOT AT ALL TIMES HOT IN RUN I/P FUSE BLOCK (LEFT SIDE OF DASH, LT BLU/BLK WIRE LT GRN WIRE LT GRN/BLK WIRE M/T A/T M/T A/T (I/P HARN, LEFT REAR OF ENGINE COMPT) OFF (OR ON (OR PNK) WIRE ORG/ WIRE PPL PPL SHIFT INTER- LOCK SYSTEM PPL/WHT WIRE STOP/HAZ FUSE 1 STOPLAMP SWITCH (TOP OF BRAKE PEDAL) VCM SIGNAL SPEED SENSOR INPUT VEHICLE CONTROL MODULE (VCM) (LEFT SIDE OF ENGINE COMPT) VEHICLE SPEED SENSOR (VSS) (LEFT SIDE OF TRANSMISSION) VSS HIGH VSS LOW WHT WIRE

16 PPL 6 7 8 8 9 PNK WIRE AUTOMATIC TRANSMISSION INPUT SHAFT SPEED (A/T ISS) SENSOR BALANCE FUEL PUMP (ON INSIDE LEFT FRAME RAIL NEAR FRONT OF REAR TANK) BLK (OR WIRE BLK WIRE BLK/WHT WIRE BLU WIRE BLU/WHT WIRE BRN WIRE BRN/WHT WIRE DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE FUEL PUMP BALANCE MODULE (INSIDE LEFT SIDE OF FRAME RAIL) FUEL PUMP BALANCE RELAY (ON FUEL PUMP BALANCE MODULE) FUEL PUMP, SENDER (IN FUEL TANK) FUEL PUMP/ OIL PRESSURE SWITCH (TOP CENTER REAR OF ENGINE, BEHIND DISTRIBUTOR) FUEL TANK PRESSURE SENSOR (CALIF ONLY) (IN FUEL TANK) GAUGES FUSE 4 GRN WIRE GRY WIRE HOT IN OFF, RUN OR START HOT IN RUN OR START I/P FUSE BLOCK IGN E FUSE INPUT FUEL GAUGE INPUT OIL GAUGE INPUT TACHOMETER INSTRUMENT CLUSTER INTAKE AIR TEMPERATURE SENSOR (IN AIR INTAKE DUCT) LT BLU/WHT WIRE LT GRN WIRE M/T ONLY MAP SENSOR PRESSURE (MAP) SENSOR (TOP RIGHT OF ENGINE, NEAR FUEL INJECTORS) MASS AIR FLOW SENSOR (IN AIR INTAKE DUCT) ORG/ WIRE OUTPUT TO GAUGE PNK (TAILLAMP EXTENSION HARN, 6 CM FROM THE FUEL PUMP HARN BREAKOUT) WIRE PNK IGNITION WIRE PNK PNK PNK WIRE PNK WIRE PPL PPL PPL PPL/WHT WIRE PRIMARY TANK FUEL LVL SIG RED WIRE RED/BLK WIRE RELAY CTRL SERVICE ENGINE SOON INDICATOR SPEEDOMETER INPUT TAN WIRE TAN/BLK WIRE THROTTLE POSITION SENSOR (ON THROTTLE BODY ASSEMBLY) TRANS FUSE 20 UNDERHOOD FUSE-RELAY CENTER UPSHIFT LAMP W/ DUAL FUEL TANKS W/O DUAL FUEL TANKS W/O DUAL FUEL TANKS W/ DUAL FUEL TANKS WHT (OR WIRE WHT WIRE YEL WIRE

A/C REQUEST SIGNAL 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) CPP SW INPUT FOUR WHL DR SIG LO CRUISE CTRL SIG ENG 23 24 CRUISE CONTROL MODULE (LEFT REAR OF ENGINE COMPARTMENT, ON FIREWALL) DATA LINK CONNECTOR (UNDER LEFT SIDE OF DASH) DISTRIBUTOR DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE ELECTRONIC BRAKE CONTROL MODULE (EBCM) (ON LEFT SIDE OF ENGINE COMPARTMENT) EVO/PASSLOCK STEERING 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 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 INPUT DATA SW SIG INPUT IGNITION IGNITION COIL (TOP LEFT REAR OF ENGINE) IGNITION COIL DRIVER (LEFT REAR SIDE 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 VSS SERIAL 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 SHIFT IND LP OUT EGR VLV FEED SPEED SENSOR SPEED STOPLAMP/ VCM SENSOR CLUTCH SIG INPUT SWITCH INPUT 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 (FOUR WHEEL DRIVE INDICATOR CIRCUIT 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

1-2 SHIFT SOL LT 2-3 SHIFT SOLENOID 3-2 SHIFT SOLENOID 6 7 8 9 10 PNK WIRE 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 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 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 7 WIRE PNK 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 UNDER HOOD FUSE/RELAY CENTER 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 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 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 SERIAL INPUT DATA SIG MANUAL OR SELECTABLE 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 SHIFT IND LP OUT EGR VLV FEED SPEED SENSOR SPEED STOPLAMP/ VCM SENSOR CLUTCH SIG INPUT SWITCH INPUT 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) 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

1-2 SHIFT SOL 2-3 SHIFT SOL 12 7 8 9 10 VSS SIG VSS RTN GROUND IGN VSS SIG 1226 1225 RANGE MODE SEL C RANGE MODE SEL B RANGE MODE SEL A 13 14 15 VSS HI VSS OUTPUT VSS OUTPUT 27 28 29 30 31 PPL A/C REQUEST SIG A/C SYSTEM A/T FLUID PRESSURE (TFP) MANUAL VALVE POSITION SWITCH ANTI-LOCK BRAKES SYSTEM AUTOMATIC TRANSMISSION BLK WIRE BLK/WHT WIRE BLU WIRE BLU/WHT WIRE BRN WIRE BRN/WHT (M/T) WIRE BRN/WHT WIRE CRUISE CONTROL SYSTEM DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE DK PNK WIRE ECT TEMP SENS IN GRN WIRE GRY WIRE GRY/BLK WIRE INLINE GENDER ADAPTER INTAKE MAN AIR TEMP SENS APP 2 SIG GLOW PLUG RELAY FORCE MTR LOW LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE LT PNK WIRE LT PPL LT PPL PPL MAP SENS INPUT FORCE MTR HI NCA WIRE ORG/ WIRE ORG/BLK WIRE OTHERS PNK PNK 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 WIRE PNK WIRE PNK/BLK WIRE POWERTRAIN CONTROL MODULE (PCM) (BEHIND RIGHT SIDE OF DASH, NEAR BLOWER MOTOR) PPL PPL (A/T) BRAKE SW IN BRAKE SWITCH INPUT CRUISE CTRL SW ENGAGE PPL (OR BRN/WHT) WIRE PPL/WHT WIRE PRESSURE CONTROL SOLENOID VALVE RADIO, EVO/ PASSLOCK CONTROL MODULE, TRANSFER CASE CONTROL MODULE RED WIRE RED/BLK WIRE SENSOR GND TAN WIRE TAN/BLK WIRE TIMING STEPPER MTR (HIGH) 3 MODE CRUISE PPL SENSOR GND SENSOR GND APP 1 SIG TIMING STEPPER MTR (LOW) TIMING STEPPER MTR (LOW) TORQUE CONVERTER CLUTCH PULSE WDTH MOD SOL TRANSMISSION SPEED INPUT TRANSMISSION TEMP INPUT TRANSMISSION TEMPERATURE SENSOR TRANSMISSIONS SYSTEM VEHICLE SPEED SENSOR (LEFT SIDE OF TRANSMISSION) VEHICLE SPEED SENSOR BUFFER (BEHIND RIGHT SIDE OF DASH) VSS VSS LO HI WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

27 28 29 30 31 PPL 5 VOLT REF ACCELERATOR PEDAL POSITION (APP) MODULE (PART OF ACCELERATOR PEDAL) BLK WIRE BLU WIRE BRAKE FUSE 18 BRN WIRE BRN/WHT WIRE CLUTCH PEDAL POSITION (CPP) SWITCH (M/T ONLY) (TOP OF CLUTCH PEDAL BRACKET) CMP SIG DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE DK PNK WIRE ECM 1 FUSE ELECTRONIC BRAKE CONTROL MODULE (ON LEFT SIDE OF ENGINE COMPT) ENGINE SHUTOFF SOLENOID (TOP OF FUEL INJECTION PUMP) GRN WIRE GRY WIRE HIGH RES SIG HOT AT ALL TIMES HOT IN HOT IN RUN OR START I/P FUSE BLOCK INJECTION TIMING STEPPER MOTOR (TOP RIGHT FRONT OF ENGINE) LT BLU WIRE LT GRN WIRE LT PPL NCA WIRE OPTICAL FUEL TEMPERATURE SENSOR (ON TOP OF FUEL INJECTION PUMP) ORG/ WIRE ORG/BLK WIRE PNK PNK 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 WIRE PNK PNK 8 9 WIRE PNK PNK PPL WIRE PNK PNK WIRE PNK WIRE PNK/BLK WIRE POWER DISTRIBUTION SYSTEM PPL PPL (OR BRN/WHT) WIRE RED WIRE RED/BLK WIRE RUN WIRE SENS GRD STOP- LAMP SWITCH (ON TOP OF BRAKE PEDAL) STOP/HAZ FUSE 1 TAN WIRE TAN/BLK WIRE TRANS FUSE 20 UNDERHOOD FUSE/RELAY CENTER WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

"GLOW PLUGS" INDICATOR 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 ECM-B FUSE FUEL BALANCE PUMP FUEL GAUGE FUEL PUMP BALANCE MODULE (INSIDE LEFT SIDE FRAME RAIL) FUEL PUMP BALANCE RELAY (ON FUEL PUMP BALANCE MODULE) FUEL PUMP PRIME CONNECTOR (LEFT SIDE OF ENG COMPT) FUEL PUMP RELAY (IN UNDER FUSE- RELAY CENTER) FUEL PUMP/OIL PRESSURE SWITCH GAUGES FUSE 4 GRN WIRE GRY WIRE HOT AT ALL TIMES UNDERHOOD FUSE/RELAY CENTER HOT IN RUN OR START I/P FUSE BLOCK IGN E FUSE INSTRUMENT CLUSTER INSTRUMENT CLUSTER SYSTEM LT BLU WIRE LT GRN WIRE NCA WIRE ORG/ WIRE PNK PNK 8 9 WIRE PNK PNK PNK WIRE PNK WIRE PPL PRIMARY TANK FUEL LEVEL SENSOR RED WIRE SERVICE ENGINE SOON INDICATOR SERVICE THROTTLE SOON INDICATOR TAN WIRE VEHICLE SPEED INPUT W/ DUAL TANKS W/O DUAL TANK W/O DUAL TANK W/ DUAL TANKS WAIT TO WATER IN FUEL INDICATOR WATER IN-FUEL SENSOR (ON FUEL FILTER/ MANAGER) WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

"SERV ENG SOON" IND ENGINE SHUTOFF SOL OUT "SERV THROTTLE SOON" IND A/C ENABLE PCM GND PCM GND A/C SYSTEM BLK WIRE BLK/WHT WIRE BLU WIRE BRN WIRE BRN/WHT WIRE DK BLU WIRE DK BLU/WHT WIRE DK GRN/WHT WIRE ENG-I FUSE FUEL SOL MODULE (5 VREF) FUSIBLE LINK FUSIBLE LINK FUSIBLE LINK GLOW GLOW PLUG 3 PLUG 1 GLOW PLUG 2 GLOW PLUG 4 GLOW PLUG 5 GLOW PLUG 6 GLOW PLUG 7 GLOW PLUG 8 GLOW PLUG OUTPUT GLOW PLUG RELAY (TOP LEFT REAR OF ENGINE) GRD GRY WIRE HOT AT ALL TIMES FUSIBLE LINK HOT IN RUN OR START LT GRN WIRE NCA WIRE ORG/ WIRE PNK IGN WIRE PNK PNK 439 439 IGNITION IGNITION WIRE PNK PNK PNK WIRE PNK WIRE POWERTRAIN CONTROL MODULE (PCM) (BEHIND RIGHT SIDE OF DASH, NEAR BLOWER MOTOR) PPL RED WIRE RELAY CTRL TAN WIRE TAN/WHT WIRE UNDERHOOD FUSE/RELAY CENTER WASTEGATE SOL ENGINE SHUTOFF SOL OUT WASTEGATE SOLENOID (TOP LEFT REAR OF ENGINE) WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

1226 1225 RANGE MODE SEL C RANGE MODE SEL B RANGE MODE SEL A 27 28 29 30 31 PPL 3/2 SHIFT SOL. PRESSURE CONTROL SOLENOID VALVE 7 8 9 10 12 13 14 15 VSS RTN GROUND A/C REQUEST SIG A/C SYSTEM A/T FLUID PRESSURE (TFP) MANUAL VALVE POSITION SWITCH ANTI-LOCK BRAKES SYSTEM AUTOMATIC TRANSMISSION BLK WIRE BLK/WHT WIRE BLU WIRE BLU/WHT WIRE BOOST PRESSURE SENSOR BRN WIRE BRN/WHT (M/T) WIRE BRN/WHT WIRE CRUISE CONTROL SWITCH DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE DK PNK WIRE ECT TEMP SENS IN BARO SENSOR INPUT GRN WIRE GRY WIRE GRY/BLK WIRE INTAKE MAN AIR TEMP SENS APP 2 SIG GLOW PLUG RELAY FORCE MTR LOW LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE LT PNK WIRE MAP SENS INPUT FORCE MTR HI NCA WIRE ORG/ WIRE ORG/BLK WIRE PNK PNK 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 WIRE PNK WIRE PNK/BLK WIRE POWERTRAIN CONTROL MODULE (PCM) (BEHIND RIGHT SIDE OF DASH, NEAR BLOWER MOTOR) PPL PPL (A/T) BRAKE SW IN BRAKE SWITCH INPUT CRUISE CTRL SW ENGAGE PPL (OR BRN/WHT) WIRE PPL/WHT WIRE RADIO RED WIRE RED/BLK WIRE RESUME SENSOR GND SET- SHIFT SOL. SHIFT SOL. TAN WIRE TAN/BLK WIRE TIMING STEPPER MTR (HIGH) 3 MODE CRUISE PPL SENSOR GND SENSOR GND APP 1 SIG TIMING STEPPER MTR (LOW) TIMING STEPPER MTR (LOW) TRANSMISSION SPEED INPUT TRANSMISSION TEMP INPUT TRANSMISSION TEMPERATURE SENSOR TRANSMISSIONS SYSTEM VEHICLE SPEED SENSOR BUFFER (BEHIND RIGHT SIDE OF DASH) VSS SIG VSS SIG VSS HI VSS OUTPUT VSS OUTPUT WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE