GMC Pickup C2500 (1985-2000) tan Wiring diagrams

419 456 389 5 15 4 MIL IND UPSHIFT IND SPEEDO ACCY BULB TEST LOCK OFF ANTI- LOCK BRAKES IND ANTI-LOCK BRAKES SYSTEM BAT IND BLK WIRE BLK/WHT WIRE BRAKE IND BRAKE PRESSURE WARNING SWITCH (ON REAR OF EBCM CASTING) BRN WIRE BRN/WHT WIRE CHECK GAUGES IND CHECK GAUGES LAMP DRIVER DAYTIME RUNNING LAMPS IND AIR BAG IND DAYTIME RUNNING LAMPS MODULE (BEHIND LEFT SIDE OF DASH, TAPED TO DASH HARNESS) DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE ENGINE CONTROLS SYSTEM (FUEL PUMP BALANCE RELAY) ENGINE COOLANT TEMPERATURE SENDER (LEFT CYLINDER HEAD) FUEL GAUGE FUEL PUMP BALANCE MODULE (INSIDE LEFT SIDE FRAME RAIL) FUEL PUMP, SENDER (IN FRONT FUEL TANK) FUEL PUMP, SENDER (IN FUEL TANK) GRN WIRE GRY WIRE HEADLIGHTS SYSTEM HI-BEAM IND HOT IN RUN OR START HOT IN RUN, BULB TEST OR START I/P FUSE BLOCK (LEFT END OF DASH) GAUGES FUSE 4 IGN IGN E MINI FUSE IGN SW BRAKE IND BRAKE PSI PK BRAKE 33 33 IGNITION COIL (RIGHT REAR OF ENGINE) IGNITION SWITCH ILLUM ILLUMINATION INSTRUMENT CLUSTER LED DIMMING LEFT TURN IND LT BLU WIRE LT GRN WIRE LT GRN/BLK WIRE M/T A/T PNK WIRE OIL GAUGE PARITY PRNDL PNK WIRE PPL PPL 9 29 30 FUEL VSS VSS PPL/WHT WIRE PRNDL PRNDL A PRNDL B PRNDL C RIGHT TURN IND RUN WIRE SAFETY BELT IND SECONDARY FUEL GAGE SENDER (IN REAR FUEL TANK) SENS RTRN FUEL IN SERVICE ENGINE SOON IND SINGLE FUEL TANK DUAL FUEL TANKS STARTING/CHARGING SYSTEM SUPPLEMENTAL RESTRAINTS SYSTEM TACH TAN WIRE TAN/BLK WIRE TAN/WHT WIRE TEMP GAUGE TRANS FUSE 20 TRANSMISSION RANGE SELECTOR (LEFT SIDE OF TRANSMISSION) TWISTED PAIR UNDERHOOD FUSE-RELAY CENTER UPSHIFT IND (M/T ONLY) VEHICLE CONTROL MODULE (LEFT SIDE OF ENGINE COMPT) VEHICLE SPEED SENSOR (LEFT REAR OF TRANSMISSION OR TRANSFER CASE) VEHICLE SPEED SENSOR (VSS) ADAPTER VOLTMETER SPEEDOMETER WARNING SYSTEMS WHT TAN/ WIRE WHT WIRE YEL WIRE

39 (OR 1020) 7.4L VIN J ONLY 900 419 507 389 12 5 15 4 FUEL RET MIL IND UPSHIFT IND SPEEDO ACCY ANTI- LOCK BRAKES IND ANTI-LOCK BRAKES SYSTEM ANTI-THEFT SYSTEM BAT IND HI BEAM IND BLK WIRE BLK/WHT WIRE BRAKE IND BRAKE PRESSURE WARNING SWITCH (ON UNDERSIDE OF ELECTRONIC BRAKE CONTROL MODULE) BRN WIRE BRN/WHT WIRE CHECK GAUGES IND CHECK GAUGES LAMP DRIVER CONVENIENCE CENTER DAYTIME RUNNING LAMPS IND AIR BAG IND DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE ELECTRONIC BRAKE CONTROL MODULE (EBCM) (ON LEFT SIDE OF ENGINE COMPT) ENGINE CONTROLS SYSTEM (FUEL PUMP BALANCE RELAY) FUEL GAUGE FUEL PUMP BALANCE MODULE (INSIDE LEFT SIDE OF FRAME RAIL) FUEL PUMP, SENDER (IN FUEL TANK) GRN WIRE GRY WIRE HEADLIGHTS SYSTEM HOT IN RUN OR START I/P FUSE BLOCK GAUGES FUSE 4 HOT IN RUN, BULB TEST OR START IGN IGN E MINI FUSE IGN SW BRAKE IND BRAKE PSI PK BRAKE 33 33 IGNITION COIL (TOP LEFT REAR OF ENGINE) IGNITION SWITCH ILLUMINATION INSTRUMENT CLUSTER LED DIMMING LEFT TURN IND LOCK OFF LT BLU WIRE LT GRN WIRE LT GRN/BLK WIRE M/T A/T PNK WIRE MALFUNC- TION INDICATOR LAMP NCA WIRE PARITY PRNDL PARK BRAKE SWITCH (ON PARK BRAKE PEDAL BRACKET) PNK WIRE PPL PPL 9 29 30 FUEL VSS VSS PPL/WHT WIRE PRNDL PRNDL A PRNDL B PRNDL C RIGHT TURN IND RUN WIRE SAFETY BELT IND SECONDARY FUEL GAUGE SENDER (IN REAR FUEL TANK) SECURITY IND SENS RTRN FUEL IN SERVICE ENGINE SOON SINGLE FUEL TANK DUAL FUEL TANKS SPEEDOMETER STARTING/CHARGING SYSTEM SUPPLEMENTAL RESTRAINTS SYSTEM TACH TAN WIRE TAN/WHT WIRE TEMP GAUGE OIL GAUGE TRANS FUSE 20 TRANSMISSION RANGE SWITCH TWISTED PAIR UNDERHOOD FUSE BLOCK UPSHIFT IND (M/T ONLY) VEHICLE CONTROL MODULE (VCM) (LEFT SIDE OF ENGINE COMPT) VEHICLE SPEED SENSOR (LEFT SIDE OF TRANSMISSION, LEFT SIDE OF TRAN- VEHICLE SPEED SENSOR (VSS) ADAPTER VOLTMETER WARNING SYSTEMS WHT WIRE YEL 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 LOW BEAM HEAD- LAMP LEFT HIGH BEAM HEAD- LAMP RIGHT HIGH BEAM 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 RIGHT LOW BEAM HEAD- LAMP RUN WIRE TAN WIRE TAN/WHT WIRE UNDERHOOD FUSE BLOCK (LEFT REAR OF ENGINE COMPT) W/ FOG LAMPS 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

"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

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 BRAKE SWITCH ASSEMBLY (AT REAR OF BRAKE PEDAL SUPPORT BRACKET) BRN WIRE BRN/WHT WIRE CLUTCH PEDAL POSITION (CPP) SWITCH (M/T ONLY) (TOP OF CLUTCH PEDAL) CMP SIG DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE ECM 1 FUSE ELECTRONIC BRAKE CONTROL MODULE (ON LEFT SIDE OF ENGINE COMPT) 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 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 PNK 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/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 BRN WIRE BRN/WHT WIRE DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE ECM-B FUSE FUEL LIFT PUMP (INSIDE LEFT FRAME RAIL, BELOW DRIVER'S DOOR) FUEL PUMP PRIME CONNECTOR FUEL PUMP RELAY (IN UNDERHOOD FUSE-RELAY CENTER) GAUGES FUSE 4 GRN WIRE GRY WIRE HOT AT ALL TIMES HOT IN RUN OR START I/P FUSE BLOCK INSTRUMENT CLUSTER INSTRUMENT CLUSTER SYSTEM INSTRUMENT CLUSTER SYSTEM (FUEL PUMP BALANCE RELAY) LT GRN WIRE ORG/ WIRE PNK PNK 8 9 WIRE PNK PNK PNK WIRE PNK WIRE RED WIRE SERVICE ENGINE SOON INDICATOR SERVICE THROTTLE SOON INDICATOR TAN WIRE UNDERHOOD FUSE-RELAY CENTER VEHICLE SPEED INPUT W/DUAL TANKS W/O DUAL TANKS WAIT TO WATER IN FUEL INDICATOR WATER IN-FUEL SENSOR (TOP CENTER REAR OF ENGINE) WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE

"SERV ENG SOON" IND ENGINE SHUTOFF SOL OUT EGR SOL OUTPUT "SERV THROTTLE SOON" IND EGR VALVE SOL PUTPUT 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 ELECTRONIC BRAKE BRAKE CONTROL MODULE (EBCM) (ON LEFT SIDE OF ENGINE COMPT) ENG-I FUSE EXHAUST GAS RECIRCULATION (EGR) VENT SOLENOID (TOP LEFT REAR OF ENGINE) EXHAUST GAS RECIRCULATION EGR SOLENOID (TOP LEFT REAR OF ENGINE) FUEL HEATER (TOP REAR OF ENGINE) FUEL SOL MODULE (5 VREF) FUSIBLE LINK FUSIBLE LINKS GLOW GLOW PLUG 3 PLUG 5 GLOW PLUG 1 GLOW PLUG 2 GLOW PLUG 4 GLOW PLUG 6 GLOW PLUG 7 GLOW PLUG 8 GLOW PLUG OUTPUT GLOW PLUG RELAY (TOP LEFT REAR OF ENGINE) GRD GROUND GRY WIRE HOT AT ALL TIMES FUSIBLE LINK HOT IN RUN OR START LT GRN 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 SIGNAL TAN WIRE TAN/WHT WIRE UNDERHOOD FUSE-RELAY CENTER WASTEGATE SOL ENGINE SHUTOFF SOL OUT WASTEGATE SOLENOID (TOP LEFT REAR OF ENGINE) WHT WIRE WHT/BLK WIRE YEL WIRE YEL/BLK WIRE