GMC Pickup C2500 (1985-2000) ppl ppl Wiring diagrams

A/T ONLY ABS FUSE ABS IND. BLK WIRE BLK/WHT WIRE BRAKE FUSE 18 BRAKE IND BRAKE PRESSURE WARNING SWITCH BRN WIRE DAYTIME RUNNING LAMPS MODULE (BEHIND LEFT SIDE OF DASH) DIODE 1 (UNDERHOOD FUSE/RELAY CENTER) DK GRN WIRE ELECTRONIC BRAKE CONTROL MODULE (LEFT SIDE OF ENGINE COMPT) FRONT AXLE ACTUATOR (RIGHT FRONT OF DRIVE AXLE) HOT AT ALL TIMES HOT IN RUN HOT IN RUN OR START GAUGES FUSE 4 I/P FUSE BLOCK IGN ABS LAMP CONTROL BRAKE SW INPUT INPUT INSTRUMENT CLUSTER LEFT FRONT WHEEL SPEED SENSOR LFT FRT SENSOR (-) LT BLU WIRE LT GRN WIRE PNK WIRE PPL PPL PPL PUMP MOTOR POWER PUMP MOTOR GROUND RED WIRE RIGHT FRONT WHEEL SPEED SENSOR RT FRT SENSOR (-) LFT FRT SENSOR (+) RT FRT SENSOR (+) TAN WIRE TAN/WHT WIRE TCC/ STOPLAMP SWITCH (TOP OF BRAKE PEDAL) UNDERHOOD FUSE-RELAY CENTER VEHICLE SPEED SENSOR BUFFER (BEHIND RIGHT SIDE OF DASH) VSS SIG OUT VSS SIG SERIAL DATA LINE SERIAL DATA SIGNAL BRAKE LAMP CONTROL EBCM GROUND YEL WIRE YEL/BLK WIRE

BLK WIRE BRN WIRE DK BLU WIRE FOG LAMP ON INDICATOR SOLID STATE SWITCH FOG LAMP RELAY (BEHIND LEFT SIDE OF I/P) FOG LAMP SWITCH GRN WIRE GRY WIRE HEADLAMP DIMMER SWITCH HEADLIGHT SWITCH ASSEMBLY HI BEAM INDICATOR HI LO HOT AT ALL TIMES HOT AT ALL TIMES FUSE BLOCK DRL-FOG FUSE ILLUM LAMP INSTRUMENT CLUSTER LEFT HEADLAMP ASSEMBLY LO HI LT GRN WIRE OFF OFF HEAD HEAD PARK ORG/ WIRE PARK PPL PPL PPL RIGHT FOG LAMP LEFT FOG LAMP RIGHT HEADLAMP ASSEMBLY TAN WIRE WHT WIRE YEL WIRE

33 (OR 1134) 592 592 150 DRL RELAY CTRL BLK WIRE BLK/WHT WIRE BRN WIRE BULB CHECK 1317 39 10 10 FOG LAMPS IGNITION LAMP FEED PNK WIRE DIODE 203 (I/P HARNESS, RIGHT SIDE OF STEERING COLUMN) DK BLU WIRE DK GRN/WHT WIRE DRL-FOG FUSE 15 FOG LAMP RELAY (UNDER LEFT END OF I/P) FOG LAMP SWITCH GAGES FUSE 4 GRN WIRE GROUND GRY WIRE HEAD HEAD OFF OFF PARK PARK HEAD- LAMP DIMMER SWITCH HEADLAMP, PANEL DIMMER SWITCH HI LO HOT AT ALL TIMES HOT IN RUN, BULB TEST OR START I/P FUSE BLOCK IGNITION SWITCH ILLUM LAMP INSTRUMENT CLUSTER HI BEAM INDI- CATOR DRL INDI- CATOR INSTRUMENT CLUSTER SYSTEM LEFT FOG LAMP RIGHT FOG LAMP LEFT HEAD- LAMP LT BLU WIRE LT GRN WIRE LT GRN/BLK WIRE NCA WIRE OFF ON INDICATOR ORG/ WIRE PARK BRAKE WARNING SWITCH (ON PARK BRAKE) PNK WIRE PPL PPL PPL RIGHT HEAD- LAMP TAN WIRE TAN/WHT WIRE W/ FOG LAMPS YEL WIRE

AUDIO ALARM MODULE (ON CONVENIENCE CENTER) AUTOMATIC TRANSFER CASE CONTROL SWITCH (LUXURY) AUTOMATIC TRANSFER CASH SELECT SWITCH AUXILIARY HEATER CONTROL BASE BLK WIRE CARGO LAMP SWITCH (PICKUP ONLY) TRANSFER CASE SWITCH CONVEN- IENCE CENTER DAYTIME RUNNING LAMP (DRL)/ RADIO OVERRIDE SWITCH DAYTIME RUNNING LAMPS (DRL)/ RADIO OVERRIDE SWITCH DISPLAY DIM SIG DISPLAY DISPLAY DIM DIM SIG SIG FOG LAMP SWITCH FRONT AUXILIARY HVAC CONTROL LAMP GRN WIRE GRY WIRE HEADLAMP, PANEL DIMMER SWITCH HOT AT ALL TIMES HVAC CONTROL LAMP I/P FUSE BLOCK ILLUM FUSE 14 ILLUMINATION INFLATABLE RESTAINT I/P MODULE SWITCH INSTRUMENT CLUSTER LIFTGATE RELEASE SWITCH (SUBUR- BAN/ UTILITIY ONLY) LUXURY OFF ORG/ WIRE PARADE MODE SW PARK PARK LPS FUSE 9 PICKUP/ EXTENDED CAB ONLY PPL PPL PPL RADIO RADIO INFLATABLE RESTAINT I/P MODULE SWITCH REAR AUXILIARY HVAC CONTROL LAMP REAR AUXILIARY HVAC CONTROL SWITCH REAR WINDOW WIPER/ WASHER SWITCH RHEO- STAT SUBURBAN, UTILITY ONLY SWITCH (SUBUR- BAN/ UTILITIY ONLY) TRANSFER CASE SHIFT ILLUMINATION LAMP TRANSFER CASE SWITCH WHT WIRE

A/T ACCY BLK WIRE BULB TEST CRANK FUSE 8 DIESEL EXCEPT DIESEL (BASE) EXCEPT DIESEL (UPLEVEL) HOLD- IN COIL I/P FUSE BLOCK (LEFT SIDE OF DASH, IGN A FUSE 6 IGNITION SWITCH LEFT BATTERY (DIESEL) LOCK OFF MEGA FUSE BLOCK (RIGHT FRONT OF ENGINE COMPT, NEAR BATTERY) NCA WIRE POWER DISTRIBUTION SYSTEM PPL PPL (RIGHT FRONT WHEELHOUSE) CLUTCH PEDAL POSITION SWITCH (TOP OF CLUTCH PEDAL) PPL A/T M/T PPL PPL PULL- IN COIL RED WIRE REMOTE BATTERY STUD RIGHT BATTERY RUN WIRE STARTER MOTOR STARTER RELAY STARTER SOLENOID TRANSMISSION RANGE SWITCH (LEFT SIDE OF TRANSMISSION) WHT WIRE YEL 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

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

10 11 PPL 2-3 SHIFT SOL CTRL AIR PUMP REL CTRL VSS SIG BLK WIRE BLK/WHT WIRE BLU WIRE BRN WIRE BRN/WHT WIRE CAM POSIT SENS SIG CAMSHAFT POSITION SENSOR (INSIDE DISTRIBUTOR) DK (ENG HARN, 11 CM FROM EGR VALVE BREAKOUT) LT DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE DK PNK WIRE FUEL LEVEL INPUT GRN WIRE IGN SENS SENS FEED SIG RTN INLINE GENDER ADAPTER KNOCK SENS SIG KNOCK SENSOR (KS) (LEFT) (LEFT SIDE OF ENGINE BLOCK, BELOW EXHAUST MANIFOLD) KNOCK SENSOR (KS) (RIGHT) (RIGHT SIDE OF ENGINE BLOCK, BELOW EXHAUST MANIFOLD) LT BLU/BLK WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE LT GRN/WHT WIRE LT LT LT PPL LT PPL/ (RIGHT FRONT SIDE OF ENG BLOCK) NCA WIRE OTHERS PNK IGNITION FEED WIRE PNK PNK 1 2 WIRE PNK PNK PNK PNK 3 4 5 6 WIRE PNK PPL WIRE PNK WIRE PNK/BLK WIRE PPL PPL PNK WIRE PPL PPL PPL SENSOR RETURN VSS RTN VSS SIGNAL CRANK POSIT SENS SIG PPL/WHT WIRE RED/BLK WIRE SENS RTN FUEL GAUGE LVL PPL SENSOR RETURN SENSOR SIGNAL TAN WIRE TAN/WHT WIRE VEHICLE CONTROL MODULE (VCM) (LEFT SIDE OF ENGINE COMPT) VEHICLE SPEED SENSOR (LEFT SIDE OF TRANSMISSION, LEFT SIDE OF VENT CTLR W/ DUAL FUEL TANKS 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