GMC C-Series mk3 (Third Generation; 2003 – 2009) – fuse box diagram
Year of production: 2003, 2004, 2005, 2006, 2007, 2008, 2009
Instrument Panel
There are two instrument panel fuse blocks located behind the instrument panel on the passenger’s side of the vehicle.
Fuse block 1
GMC C-Series mk3 – fuse box – instrument panel (fuse block 1)
| Fuse |
Circuits protected |
| RH PARK LP |
Right-hand Parking Lamps |
| LH PARK LP |
Left-hand Parking Lamps |
| RADIO U |
Radio |
| PWR WINDOW |
Power Windows |
| BRAKE ISO |
Brake Warning Lamp |
| SPARE |
Spare Fuse |
| L-RR TRUCK |
Left Rear Trailer Wiring |
| SPARE |
Spare Fuse |
| SPARE |
Spare Fuse |
| SPARE |
Spare Fuse |
| R-RR TRUCK |
Right Rear Trailer Wiring |
| SPARE |
Spare Fuse |
| Relay |
Circuits protected |
| BRAKE LAMP |
C4/C5 Brake Lamps, C6/C7/C8 Tractor/Trailer Wiring |
| IGN 4 |
Ignition |
| MARKER LP |
Sidemarker and Clearance Lamps |
| HTD FUEL |
LB7/LG4 Heated Fuel |
| AIR HTR |
LG4 Air Heater |
| ECU MAINTAIN |
LG4 Electronic Control Unit |
| DRL |
Daytime Running Lamps |
| CHMSL ISO |
Center High Mounted Stop Lamp |
| HTD MIRR |
Heated Mirrors |
| R-TRN TLR |
Right Trailer Turn Signal |
| L-TRN TLR |
Left Trailer Turn Signal |
| SPARE |
Spare Relay |
| SPARE |
Spare Relay |
| SPARE |
Spare Relay |
Fuse block 2
GMC C-Series mk3 – fuse box – instrument panel (fuse block 2)
| Circuit Breaker |
Usage |
| 1 |
Stoplamps |
| 2 |
Center High Mounted Stop Lamp |
| 3 |
Parking Lamps |
| 4 |
Powertrain Control Module |
| 5 |
Auxiliary Wiring |
| 6 |
Heater/Air Conditioning |
| 7 |
Hazard Warning Flashers |
| 8 |
Power Post |
| 9 |
Courtesy Lamps |
| 10 |
Warning Lights, Gages and Indicators |
| 11 |
Crank |
| 12 |
Rear Axle |
| 13 |
Trailer Turn Signals/Hazard Warning Flashers |
| 14 |
Radio/Chime |
| 15 |
Daytime Running Lamps |
| 16 |
Air Bag System |
| 17 |
Exterior/Interior Lamps |
| 18 |
Parking Brake |
| 19 |
Accessory Power |
| 20 |
Ignition |
| 21 |
Sidemarker Lamps |
| 22 |
Turn Signal/Backup Lamps |
| 23 |
Transmission |
| 24 |
Chassis |
| A |
Spare |
| B |
Spare |
Underhood Fuse Block
There are two underhood fuse blocks located in the engine compartment, on the
passenger’s side of the vehicle.
Primary Underhood fuse block
GMC C-Series mk3 – fuse box – engine compartment (primary fuse block)
| Relay |
Usage |
| NOTE 1 |
LG4 Powertrain Control Valve, L18/LB7 Fuel Pump, LG5 Heated Fuel |
| IGN B |
Ignition |
| STARTER |
Starter |
| HORN |
Horn |
| IGN A |
Ignition |
| PTO |
Power Take-Off |
| REVERSE |
Reverse |
| NEUTRAL START |
Neutral Start |
| Fuse |
Usage |
| RR DEFOG |
Rear Defog |
| ENG 1 |
Engine 1 |
| ENG 3 |
Engine 3 |
| PCM-B |
Powertrain Control Module |
| BLANK |
Empty |
| ENG 4 |
Engine 4 |
| ENG 2 |
Engine 2 |
| BLANK |
Empty |
| BLANK |
Empty |
| BLANK |
Empty |
| A/C COMP |
Air Conditioning Compressor |
| ABS 1 |
Anti-Lock Brake System 1 |
| ABS 2 |
Anti-Lock Brake System 2 |
| ABS 3 |
Anti-Lock Brake System 3 |
| ENGINE |
Engine |
| E/A PUMP |
Electronic/Automatic Pump |
| HORN |
Horn |
| NOTE 2 |
L18/LB7 Fuel, LG4 Powertrain Control Valve, LG5 Electronic Control Module |
| BLANK |
Empty |
| STUD A |
Spare |
| STUD B |
Spare |
Secondary Underhood Fuse Block
GMC C-Series mk3 – fuse box – engine compartment (secondary fuse block)
| Fuse |
Usage |
| IGN 1 |
Ignition 1 |
| IGN 4 |
Ignition 4 |
| IGN 3 |
Ignition 3 |
| BATT/HAZ |
Battery/Hazard Warning Flashers |
| HEADLAMP |
Headlamps |
| LIGHTING |
Interior/Exterior Lamps |
| HVAC |
Comfort Control System |
| NOTE |
C4/C5 Electric Brake, C6/C7/C8 Brake Lamps |
WARNING: Terminal and harness assignments for individual connectors will vary depending on vehicle equipment level, model, and market.
