Jonathan Yarden Mar 25, 2021 · 5 min. read
In this article you will find a description of fuses and relays GMC,
with photos of block diagrams and their locations.
Highlighted the cigarette lighter fuse (as the most popular thing people look for).
Get tips on blown fuses, replacing a fuse, and more.
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 passengerâs side of the vehicle.
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/C8Â Tractor/Trailer Wiring |
| IGN 4 | Ignition |
| MARKER LP | Sidemarker and Clearance Lamps |
| HTD FUEL | LB7/LG4 Heated Fuel |
| AIR HTR | LG4 Air Heater |
| ECUÂ 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
| 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 |
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Underhood Fuse Block
There are two underhood fuse blocks located in the engine compartment, on the
passengerâs side of the vehicle.
Primary Underhood 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
| 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:Â Terminal and harness assignments for individual connectors will vary depending on vehicle equipment level, model, and market.
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