GMC Sierra 2500 (2000-2004) ref lo Wiring diagrams

28 29 30 PNK WIRE A/C REQ A/C SYSTEM AIR PUMP ANTI-LOCK BRAKE SYSTEM ANTI-LOCK BRAKE SYSTEM (SPEED SIGNAL) AUTOMATIC TRANSFER CASE CONTROL MODULE (ABOVE HEADLIGHT SWITCH) BLK WIRE BLK/ GRY WIRE BLK/WHT WIRE BRN WIRE BRN/WHT WIRE CRUISE CONTROL SYSTEM CRUISE ENG CTRL DELIVERED TORQ PC SOL HI EGR CTRL PC SOL LO FUEL PMP RPM OUT RECIRC SW DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE EVAP VENT MIL CTRL 2-3 SS 1-2 SS VSS OUT VSS OUT TFT SENS SIG GEN F FRONT AXLE SWITCH (RIGHT SIDE OF CENTER ON AXLE HOUSING) FRT AXLE SW VSS LOW VSS HIGH FUSE FUSE BLOCK GEN L GRY WIRE GRY/BLK WIRE HOT IN RUN, START IAC COIL HI IAC COIL LO IAC COIL LO IAC COIL HI IDLE AIR CONTROL VALVE (TOP OF THROTTLE BODY) IGN IGN CTRL IGN CTRL IGN CTRL IGN CTRL IGN FEED GND EGR GND TCC SOL A/C CLU IGNITION COILS INSTRUMENT CLUSTER SYSTEMS (SPEED SIGNAL) INSTRUMENT PANEL CLUSTER MALFUNCTION INDICATOR LAMP LT BLU WIRE LT BLU/BLK WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE LT GRN/WHT WIRE MAF SIG MAP SIG RECIRC DOOR EVAP CANP NCA WIRE PNK PNK WIRE PNK WIRE POWERTRAIN CONTROL MODULE (LEFT FRONT OF ENGINE COMPT) PPL PPL FUEL LEV CYC SW IN PPL PNK PNK 24 25 26 27 WIRE PPL/WHT WIRE RED WIRE RED/BLK WIRE RED/WHT WIRE REF LO REF LOW REF LOW PRND C TRANS RNG A FUEL SIG CTRL RPM OUT SENS GND SPARK PLUG SPARK PLUG SPARK PLUG STARTING/CHARGING SYSTEM TAN WIRE TAN/BLK WIRE TP SIG IAT SIG IGN CTRL IGN CTRL IGN CTRL IGN CTRL TRANSFER CASE SWITCH (LEFT FRONT OF TRANSAXLE CASE) UNDER- HOOD JUNCTION BLOCK W/ ATC WHT WIRE YEL WIRE YEL/BLK WIRE

28 29 30 PNK WIRE A/C REQ A/C SYSTEM AIR PUMP ANTI-LOCK BRAKE SYSTEM ANTI-LOCK BRAKE SYSTEM (SPEED SIGNAL) AUTOMATIC TRANSFER CASE CONTROL MODULE (ABOVE HEADLIGHT SWITCH) BLK WIRE BLK/ GRY WIRE BLK/WHT WIRE BRN WIRE BRN/WHT WIRE CRUISE CONTROL SYSTEM CRUISE ENG CTRL DELIVERED TORQ PC SOL HI EGR CTRL PC SOL LO FUEL PMP RPM OUT RECIRC SW DK BLU WIRE DK GRN WIRE DK GRN/WHT WIRE EVAP VENT MIL CTRL 2-3 SS 1-2 SS VSS OUT VSS OUT TFT SENS SIG GEN F FRONT AXLE SWITCH (RIGHT SIDE OF CENTER ON AXLE HOUSING) FRT AXLE SW VSS LOW VSS HIGH FUSE FUSE BLOCK GEN L GRY WIRE GRY/BLK WIRE HOT IN RUN, START IAC COIL HI IAC COIL LO IAC COIL LO IAC COIL HI IDLE AIR CONTROL VALVE (TOP OF THROTTLE BODY) IGN IGN CTRL IGN CTRL IGN CTRL IGN CTRL IGN FEED GND EGR GND TCC SOL A/C CLU IGNITION COILS INSTRUMENT CLUSTER SYSTEMS (SPEED SIGNAL) INSTRUMENT PANEL CLUSTER MALFUNCTION INDICATOR LAMP LT BLU WIRE LT BLU/BLK WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE LT GRN/WHT WIRE MAF SIG MAP SIG RECIRC DOOR EVAP CANP NCA WIRE PNK PNK WIRE PNK WIRE POWERTRAIN CONTROL MODULE (LEFT FRONT OF ENGINE COMPT) PPL PPL FUEL LEV CYC SW IN PPL PNK PNK 24 25 26 27 WIRE PPL/WHT WIRE RED WIRE RED/BLK WIRE RED/WHT WIRE REF LO REF LOW REF LOW PRND C TRANS RNG A FUEL SIG CTRL RPM OUT SENS GND SPARK PLUG SPARK PLUG SPARK PLUG STARTING/CHARGING SYSTEM TAN WIRE TAN/BLK WIRE TP SIG IAT SIG IGN CTRL IGN CTRL IGN CTRL IGN CTRL TRANSFER CASE SWITCH (LEFT FRONT OF TRANSAXLE CASE) UNDER- HOOD JUNCTION BLOCK W/ ATC WHT WIRE YEL WIRE YEL/BLK WIRE

33 34 35 PNK WIRE A/C SYSTEM A/C SYSTEM STARTING/CHARGING SYSTEM TRANSMISSIONS SYSTEM AIR CONDITIONING SYSTEM ANTI-LOCK BRAKES SYSTEM BLK WIRE BLK/WHT WIRE BRN WIRE BRN/WHT WIRE CRANK FUSE CTRL CYCLE SIG DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE EVAP VENT CTRL MIL CTRL 2-3 SS CTRL 1-2 SS CTRL VSS OUT VSS OUT TFT SENS SIG EXC SEO FUSE GRY WIRE GRY/BLK WIRE HOT AT ALL TIMES HOT IN RUN, START HOT IN START IGN IGN CTRL IGN CTRL IGN CTRL IGN CTRL IGN FEED GND IGNITION COILS INSTRUMENT CLUSTER SYSTEM INSTRUMENT PANEL CLUSTER IPC/DIC FUSE LOGIC LT BLU WIRE LT BLU/BLK WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE MALFUNCTION INDICATOR LAMP NCA WIRE ORG/ WIRE PC SOL HI CTRL PC SOL LO CTRL PMP RLY CTRL RPM OUT PNK 10 11 12 13 14 15 16 17 18 19 WIRE PNK PNK WIRE PNK WIRE PNK/BLK WIRE POWERTRAIN CONTROL MODULE (LEFT FRONT OF ENGINE COMPT) PPL PPL FUEL LEV SIG PPL PNK PNK WIRE PPL/WHT WIRE PRESS SENS SIG IND CTRL RED WIRE RED/BLK WIRE RED/WHT WIRE REF LO REF LOW RPM OUT SEO SPARK PLUG SPARK PLUG SPARK PLUG STARTING/CHARGING SYSTEM TAN WIRE TAN/BLK WIRE TAN/WHT WIRE TCC SOL CLU RLY CTRL TRANSMISSIONS SYSTEM UNDERHOOD FUSE BLOCK WHT WIRE YEL WIRE YEL/BLK WIRE

31 32 33 PNK WIRE A/C SYSTEM A/C SYSTEM STARTING/CHARGING SYSTEM TRANSMISSIONS SYSTEM AIR CONDITIONING SYSTEM ANTI-LOCK BRAKES SYSTEM BLK WIRE BLK/WHT WIRE BRN WIRE BRN/WHT WIRE CRANK FUSE FUSE CTRL CYCLE SIG DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE EVAP VENT CTRL MIL CTRL 2-3 SS CTRL 1-2 SS CTRL VSS OUT VSS OUT TFT SENS SIG EXC SEO FUSE GRY WIRE GRY/BLK WIRE HOT AT ALL TIMES HOT IN HOT IN RUN, START IGN IGN CTRL IGN CTRL IGN CTRL IGN CTRL IGN FEED GND IGNITION COILS INSTRUMENT CLUSTER SYSTEM INSTRUMENT PANEL CLUSTER IPC/DIC FUSE LOGIC LT BLU WIRE LT BLU/BLK WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE MALFUNCTION INDICATOR LAMP NCA NCA WIRE NCA WIRE ORG/ WIRE PC SOL HI CTRL PC SOL LO CTRL PMP RLY CTRL RPM OUT PNK 10 11 12 13 14 15 16 17 18 WIRE PNK PNK WIRE PNK WIRE PNK/BLK WIRE POWERTRAIN CONTROL MODULE (LEFT FRONT OF ENGINE COMPT) PPL PPL FUEL LEV SIG PPL/WHT WIRE PRESS SENS SIG IND CTRL RED WIRE RED/BLK WIRE RED/WHT WIRE REF LO REF LOW RPM OUT SEO SPARK PLUG SPARK PLUG SPARK PLUG STARTING/CHARGING SYSTEM TAN WIRE TAN/BLK WIRE TAN/WHT WIRE TCC SOL CLU RLY CTRL TRANSMISSIONS SYSTEM UNDERHOOD FUSE BLOCK WHT WIRE YEL WIRE YEL/BLK WIRE

32 33 34 PNK WIRE A/C SYSTEM A/C SYSTEM STARTING/CHARGING SYSTEM TRANSMISSIONS SYSTEM AIR CONDITIONING SYSTEM ANTI-LOCK BRAKES SYSTEM BLK WIRE BLK/WHT WIRE BRN WIRE BRN/WHT WIRE CLU RLY CTRL CRANK FUSE CTRL CYCLE SIG DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE EVAP VENT CTRL MIL CTRL 2-3 SS CTRL 1-2 SS CTRL VSS OUT VSS OUT TFT SENS SIG EXC SEO FUSE GRY WIRE GRY/BLK WIRE HOT AT ALL TIMES HOT IN RUN, START HOT IN START IGN IGN CTRL IGN CTRL IGN CTRL IGN CTRL IGN FEED GND IGNITION COILS INSTRUMENT CLUSTER SYSTEM INSTRUMENT PANEL CLUSTER IPC/DIC FUSE LOGIC LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE MALFUNCTION INDICATOR LAMP NCA WIRE ORG/ WIRE PC SOL HI CTRL PC SOL LO CTRL PMP RLY CTRL RPM OUT PNK 10 11 12 13 14 15 16 17 18 WIRE PNK PNK WIRE PNK WIRE POWERTRAIN CONTROL MODULE (LEFT FRONT OF ENGINE COMPT) PPL PPL FUEL LEV SIG PPL PNK PNK WIRE PPL/WHT WIRE PRESS SENS SIG IND CTRL RED WIRE RED/BLK WIRE RED/WHT WIRE REF LO REF LOW RPM OUT SEO SPARK PLUG SPARK PLUG SPARK PLUG STARTING/CHARGING SYSTEM TAN WIRE TAN/WHT WIRE TRANSMISSIONS SYSTEM UNDERHOOD FUSE BLOCK WHT WIRE YEL WIRE YEL/BLK WIRE

33 34 35 PNK WIRE A/C SYSTEM A/C SYSTEM STARTING/CHARGING SYSTEM TRANSMISSIONS SYSTEM AIR CONDITIONING SYSTEM ANTI-LOCK BRAKES SYSTEM BLK WIRE BLK/WHT WIRE BRN WIRE BRN/WHT WIRE CRANK FUSE CSS SIG AXLE SW SIG VSS LOW SIG VSS HIGH SIG AT ISS HIGH SIG AT ISS LOW SIG CTRL CYCLE SIG DELIVERED TORQ PC SOL HI CTRL DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE EVAP CANP CTRL EVAP VENT CTRL MIL CTRL 2-3 SS CTRL 1-2 SS CTRL VSS OUT VSS OUT TFT SENS SIG EXC SEO FUEL LEV SENS FUSE GRY WIRE GRY/BLK WIRE HOT AT ALL TIMES HOT IN RUN, START HOT IN START IAT SIG IGN CTRL IGN CTRL IGN CTRL IGN CTRL PPL IGN IGN CTRL IGN CTRL IGN CTRL IGN CTRL IGN FEED GND IGNITION COILS INSTRUMENT CLUSTER SYSTEM INSTRUMENT PANEL CLUSTER IPC/DIC FUSE LOGIC LT BLU WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE MAF SIG MAP SIG MALFUNCTION INDICATOR LAMP NCA WIRE ORG/ WIRE PC SOL LO CTRL PMP RLY CTRL RPM OUT PNK 11 12 13 14 15 16 17 WIRE PNK PNK WIRE PNK WIRE POWERTRAIN CONTROL MODULE (LEFT FRONT OF ENGINE COMPT) PPL PPL FUEL LEV SIG PPL PNK PNK WIRE PPL/WHT WIRE PRESS SENS SIG IND CTRL RED WIRE RED/BLK WIRE RED/WHT WIRE REF LO REF LOW RPM OUT SEO SPARK PLUG SPARK SPARK PLUG PLUG STARTING/CHARGING SYSTEM STARTING/CHARGING SYSTEM TRANSMISSIONS SYSTEM TAN WIRE TAN/BLK WIRE TAN/WHT WIRE TCC SOL CTRL CLU RLY CTRL UNDERHOOD FUSE BLOCK WHT WIRE YEL WIRE YEL/BLK WIRE

1 2 3 PNK PNK WIRE 29 30 31 PNK WIRE A/C CLU A/C REQ A/C SYSTEM A/C SYSTEM 1310 419 1223 1222 1827 AIR PUMP ANTI-LOCK BRAKE SYSTEM ANTI-LOCK BRAKE SYSTEM (SPEED SIGNAL) AUTOMATIC TRANS- MISSION INPUT SHAFT SPEED SENSOR AUTOMATIC TRANSFER CASE CONTROL MODULE (ABOVE HEADLIGHT SWITCH) BLK WIRE BLK/ GRY WIRE BLK/WHT WIRE BRN WIRE BRN/WHT WIRE CRUISE CONTROL SYSTEM CRUISE ENG CTRL DELIVERED TORQ PC SOL HI EGR CTRL PC SOL LO FUEL PMP RPM OUT RECIRC SW DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE ENGINE WIRING HARNESS JUNCTION BLOCK EVAP VENT MIL CTRL 2-3 SS 1-2 SS VSS OUT VSS OUT TFT SENS SIG GEN F FRONT AXLE SWITCH (RIGHT SIDE OF CENTER ON AXLE HOUSING) FRT AXLE SW VSS LOW VSS HIGH FUSE FUSE BLOCK GEN L GRY WIRE GRY/BLK WIRE HOT IN RUN, START IAC COIL HI IAC COIL LO IAC COIL LO IAC COIL HI IDLE AIR CONTROL VALVE (TOP OF THROTTLE BODY) IGN IGN CTRL IGN CTRL IGN CTRL IGN CTRL IGN FEED GND EGR GND IGNITION COILS INSTRUMENT CLUSTER MALFUNCTION INDICATOR LAMP INSTRUMENT CLUSTER SYSTEMS (SPEED SIGNAL) LT BLU WIRE LT BLU/BLK WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE LT GRN/WHT WIRE MAF SIG MAP SIG RECIRC DOOR EVAP CANP NCA WIRE PNK WIRE POWERTRAIN CONTROL MODULE (LEFT FRONT OF ENGINE COMPT) PPL PPL FUEL LEV CYC SW IN PPL PNK PNK WIRE PPL/WHT WIRE RED WIRE RED/BLK WIRE RED/WHT WIRE REF LO REF LOW REF LOW PRND C TRANS RNG A FUEL SIG CTRL RPM OUT SEC FUEL LVL SEC FUEL PMP SENS GND SPARK PLUG SPARK PLUG SPARK PLUG STARTING/CHARGING SYSTEM TAN WIRE TAN/BLK WIRE TP SIG IAT SIG IGN CTRL IGN CTRL IGN CTRL IGN CTRL TRANSFER CASE SWITCH (LEFT FRONT OF TRANSAXLE CASE) W/ ATC WHT WIRE YEL WIRE YEL/BLK WIRE

A/C CLU A/C REQ A/C SYSTEM A/C SYSTEM 1310 419 1223 1222 1827 ANTI-LOCK BRAKE SYSTEM ANTI-LOCK BRAKE SYSTEM (SPEED SIGNAL) AUTOMATIC TRANS- MISSION INPUT SHAFT SPEED SENSOR BLK WIRE BLK/ GRY WIRE BLK/WHT WIRE BRN WIRE BRN/WHT WIRE CRUISE CONTROL SYSTEM CRUISE ENG CTRL DELIVERED TORQ PC SOL HI EGR CTRL PC SOL LO FUEL PMP RPM OUT RECIRC SW DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE EVAP VENT MIL CTRL 2-3 SS 1-2 SS VSS OUT VSS OUT TFT SENS SIG GEN F FUSE GEN L GRY WIRE GRY/BLK WIRE HOT IN RUN, START IAC COIL HI IAC COIL LO IAC COIL LO IAC COIL HI IDLE AIR CONTROL VALVE (TOP OF THROTTLE BODY) IGN IGN CTRL IGN CTRL IGN CTRL IGN CTRL IGN FEED GND EGR GND IGNITION COILS INSTRUMENT CLUSTER SYSTEMS (SPEED SIGNAL) INSTRUMENT PANEL CLUSTER MALFUNCTION INDICATOR LAMP LEFT I/P FUSE BLOCK LT BLU WIRE LT BLU/BLK WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE LT GRN/WHT WIRE MAF SIG MAP SIG RECIRC DOOR EVAP CANP NCA WIRE PNK PNK WIRE PNK WIRE POWERTRAIN CONTROL MODULE (LEFT FRONT OF ENGINE COMPT) PPL PPL FUEL LEV CYC SW IN PPL PNK PNK WIRE PPL/WHT WIRE RED WIRE RED/BLK WIRE RED/WHT WIRE REF LO REF LOW REF LOW PRND C TRANS RNG A FUEL SIG CTRL RPM OUT SEC FUEL LVL SENS GND SPARK PLUG SPARK SPARK PLUG PLUG STARTING/CHARGING SYSTEM TAN WIRE TAN/BLK WIRE TP SIG IAT SIG IGN CTRL IGN CTRL IGN CTRL IGN CTRL TRANSFER CASE SHIFT CONTROL MODULE (BEHIND HEADLIGHT SWITCH) UNDERHOOD FUSE BLOCK VSS LOW VSS HIGH WHT WIRE YEL WIRE YEL/BLK WIRE

1 2 3 4 5 6 7 PNK PNK WIRE 29 30 31 PNK WIRE A/C CLU A/C REQ A/C SYSTEM A/C SYSTEM 1310 419 1223 1222 1827 ANTI-LOCK BRAKE SYSTEM ANTI-LOCK BRAKE SYSTEM (SPEED SIGNAL) AUTOMATIC TRANS- MISSION INPUT SHAFT SPEED SENSOR BLK WIRE BLK/ GRY WIRE BLK/WHT WIRE BRN WIRE BRN/WHT WIRE CRUISE CONTROL SYSTEM CRUISE ENG CTRL DELIVERED TORQ PC SOL HI EGR CTRL PC SOL LO FUEL PMP RPM OUT RECIRC SW DK BLU WIRE DK BLU/WHT WIRE DK GRN WIRE DK GRN/WHT WIRE EVAP VENT MIL CTRL 2-3 SS 1-2 SS VSS OUT VSS OUT TFT SENS SIG GEN F FUSE GEN L GRY WIRE GRY/BLK WIRE HOT IN RUN, START IAC COIL HI IAC COIL LO IAC COIL LO IAC COIL HI IDLE AIR CONTROL VALVE (TOP OF THROTTLE BODY) IGN IGN CTRL IGN CTRL IGN CTRL IGN CTRL IGN FEED GND EGR GND IGNITION COILS INSTRUMENT CLUSTER SYSTEMS (SPEED SIGNAL) INSTRUMENT PANEL CLUSTER MALFUNCTION INDICATOR LAMP LEFT I/P FUSE BLOCK LT BLU WIRE LT BLU/BLK WIRE LT BLU/WHT WIRE LT GRN WIRE LT GRN/BLK WIRE LT GRN/WHT WIRE MAF SIG MAP SIG RECIRC DOOR EVAP CANP NCA WIRE PNK WIRE POWERTRAIN CONTROL MODULE (LEFT FRONT OF ENGINE COMPT) PPL PPL FUEL LEV CYC SW IN PPL PNK PNK WIRE PPL/WHT WIRE RED WIRE RED/BLK WIRE RED/WHT WIRE REF LO REF LOW REF LOW PRND C TRANS RNG A FUEL SIG CTRL RPM OUT SEC FUEL LVL SENS GND SPARK PLUG SPARK SPARK PLUG PLUG STARTING/CHARGING SYSTEM TAN WIRE TAN/BLK WIRE TP SIG IAT SIG IGN CTRL IGN CTRL IGN CTRL IGN CTRL TRANSFER CASE SHIFT CONTROL MODULE (BEHIND HEADLIGHT SWITCH) UNDERHOOD FUSE BLOCK VSS LOW VSS HIGH WHT WIRE YEL WIRE YEL/BLK WIRE