Where are the Fuse Boxes located in the 2003 GMC Sierra?
2003 GMC Sierra has 2 main boxes with fuses and relays. One is in the cabin (Passenger Compartment) and another is under the hood (Engine Compartment).
2003 GMC Sierra Under Dash Fuse Box and Relay Location
The Fuse and Relay box is located under the dashboard, on the driver side, below the steering, and is covered with trim.
2003 GMC Sierra under Dash Fuse Box Layout
2003 GMC Sierra under Dash Fuse and relay Box Diagram
Instrument Panel Fuse Block
The Fuse Block access door is on the Driver’s side edge of the Instrument Panel. Pull off the cover to access to fuse block
2003 GMC Sierra Under Dash Fuse and relay Box Details
Assignment of the fuses in the Instrument Panel Fuse Block
| Name | Usage |
|---|---|
| RR Wiper | Not Used |
| SEO ACCY | Special Equipment Option Accessory |
| WSWPR | Windshield Wipers |
| TBC ACCY | Truck Body Controller Accessory |
| IGN 3 | Ignition, Heated Seats |
| 4WD | Four-Wheel Drive System, Auxiliary Battery |
| HTR A/C | Climate Control System |
| LOCK (Relay) | Power Door Lock Relay (Lock Function) |
| HVAC1 | Climate Control System |
| LDOOR | Driver’s Door Harness Connection |
| CRUISE | Cruise Control, Power Take Off (PTO) |
| UNLOCK (Relay) | Power Door Lock Relay (Unlock Function) |
| RR FOG LP | Not Used |
| BRAKE | Anti-Lock Brake System |
| DRIVER UNLOCK | Power Door Lock Relay (Driver’s Door Unlock Function) |
| IGN 0 | TCM |
| TBC IGN 0 | Truck Body Controller |
| VEH CHMSL | Vehicle and Trailer High Mounted Stoplamp |
| LT TRLR ST/TRN | Left Turn Signal/Stop Trailer |
| LTTRN | Left Turn Signals and Sidemarkers |
| VEH STOP | Vehicle Stoplamps, Brake Module, Electronic Throttle Control Module |
| RT TRLR ST/TRN | Right Turn Signal/Stop Trailer |
| RTTRN | Right Turn Signals and Sidemarfcers |
| BODY | Harness Connector |
| DDM | Driver Door Module |
| AUX PWR 2 | Not Used |
| LOCKS | Power Door Lock System |
| ECC | Not Used |
| TBC 2C | Truck Body Controller |
| FLASH | Flasher Module |
| CB LT DOORS | Left Power Windows Circuit Breaker |
| TBC 2B | Truck Body Controller |
| TBC 2A | Truck Body Controller |
Center Instrument Panel Block
The center instrument utility block is located underneath the instrument panel, to the left of the steering column.
Assignment of the fuses in the Center Instrument Panel Fuse Block
| Name | Usage |
|---|---|
| SEO | Special Equipment Option |
| TRAILER | Trailer Brake Wiring |
| UPFIT | Uptitter (Not Used) |
| SL RIDE | Ride Control Harness Connection |
| HDLR 2 | Headliner Wiring Connector |
| BODY | Body Wiring Connector |
| DEFOG | Rear Defogger Relay |
| HDLNR 1 | Headliner Wiring Connector 1 |
| SPARE RELAY | Not Used |
| CB SEAT | Driver and Passenger Seat Module Circuit Breaker |
| CB RT DOOR | Right Power Windows Circuit Breaker |
| SPARE | Not Used |
| INFO | Infotainment Harness Connection |
2003 GMC Sierra Under Hood Fuse and Relay box location
The Under Hood Fuse Block in the Engine Compartment on the driver’s side of the vehicle near the battery. Lift the cover for access to the fuse/relay block.
2003 GMC Sierra Under Hood Fuse Box Layout
2003 GMC Sierra under Hood Fuse and relay Box Diagram
2003 GMC Sierra under Hood Fuse Box Details
Assignment of the fuses in the Engine compartment
| Name | Usage |
|---|---|
| GLOW PLUG | Diesel Glow Plugs and Intake Air Heater |
| CUST FEED | Gasoline Accessory Power |
| STUD #1 | Auxiliary Power (Single Battery and Diesels Only)/ Dual Battery (TP2) Do not install fuse. |
| MBEC | Mid Bussed Electrical Center Power Feed, Front Seats, Right Doors |
| BLOWER | Front Climate Control Fan |
| LBEC | Left Bussed Electrical Center, Door Modules, Door Locks, Auxiliary Power Outlet-Rear Cargo Area and Instrument Panel |
| STUD 2 | Accessory Power/Trailer Wiring Brake Feed |
| ABS | Anti-Lock Brakes |
| VSES/ECAS | Vehicle Stability |
| IGN A | Ignition Power |
| IGN B | Ignition Power |
| LBEC 1 | Left Bussed Electrical Center, Left Doors, Truck Body Controller, Flasher Module |
| TRL PARK | Parking Lamps Trailer Wiring |
| RR PARK | Right Rear Parking and Sidemarker Lamps |
| LR PARK | Left Rear Parking and Sidemarker Lamps |
| PARK LP | Parking Lamps Relay |
| STARTER | Starter Relay |
| INTPARK | Interior Lamps |
| STOP LP | Stoplamps |
| TBC BATT | Truck Body Controller Battery Feed |
| SUNROOF | Sunroof |
| SEO B2 | Off-Road Lamps |
| 4WS | Vent Solenoid Canister/Quadrasteer Module Power |
| RR HVAC | Not Used |
| AUX PWR | Auxiliary Power Outlet — Console |
| IGN 1 | Ignition Relay |
| PCM 1 | Powertrain Control Module |
| ETC/ECM | Electronic Throttle Control, Electronic Brake Controller |
| IGNE | Instrument Panel Cluster, Air Conditioning Relay, Turn Signal/Hazard Switch, Starter Relay |
| RTD | Ride Control |
| TRL B/U | Backup Lamps Trailer Wiring |
| PCM B | Powertrain Control Module, Fuel Pump |
| F/PMP | Fuel Pump (Relay) |
| B/U LP | Back-up Lamps, Automatic Transmission Shift Lock Control System |
| RR DEFOG | Rear Window Defogger |
| HDLP-HI | Headlamp High Beam Relay |
| PRIME | Not Used |
| O2B | Oxygen Sensors |
| SIR | Supplemental Inflatable Restraint System |
| FRT PARK | Front Parking Lamps, Sidemarker Lamps |
| DRL | Daytime Running Lamps (Relay) |
| SEO IGN | Rear Defog Relay |
| TBC IGN1 | Truck Body Controller Ignition |
| HI HDLP-LT | High Beam Headlamp-Left |
| LH HID | Not Used |
| DRL | Daytime Running Lamps |
| IPC/DIC | Instrument Panel Cluster/Driver Information Center |
| HVAC/ECAS | Climate Control Controller |
| CIGLTR | Cigarette Lighter |
| HI HDLP-RT | High Beam Headlamp-Right |
| HDLP-LOW | Headlamp Low Beam Relay |
| A/C COMP | Air Conditioning Compressor |
| A/C COMP | Air Conditioning Compressor Relay |
| RRWPR | Not Used |
| RADIO | Audio System |
| SEO B1 | Mid Bussed Electrical Center, Rear Heated Seats, HomeLink |
| LO HDLP-LT | Headlamp Low Beam-Left |
| BTSI | Brake Transmission Shift Interfock System |
| CRANK | Starting System |
| LO HDLP-RT | Headlamp Low Beam-Right |
| BTSI | Brake Transmission Shift Interlock System |
| CRANK | Starting System |
| LO HDLP- RT | Headlamp Low Beam-Right |
| FOG LP | Fog Lamp Relay |
| FOG LP | Fog Lamps |
| HORN | Horn Relay |
| W/S WASH | Windshield Washer Pump Relay |
| W/S WASH | Windshield Washer Pump |
| INFO | OnStar/Rear Seat Entertainment |
| RADIO AMP | Radio Amplifier |
| RH HID | Not Used |
| HORN | Horn |
| EAP | Not Used |
| TREC | All-Wheel Drive Module |
| SBA | Supplemental Brake Assist |
| *1 | — Gasoline Engine and Diesel Engine. |
| *2 | — Gasoline Engine; ECMRPV – Diesel Engine. |
| *3 | — Gasoline Engine; FUEL HT – Diesel Engine. |
| *4 | — Gasoline Engine; ECM I – Diesel Engine. |
| *5 | IGN/EDU |
Auxiliary Fuse Box(Engine Compartment)
The auxiliary electric cooling fan fuse block is located in the engine compartment on the driver’s side of the vehicle next to the underhood fuse block.
Assignment of the fuses in the Engine compartment auxiliary box
| Name | Description |
|---|---|
| COOL/FAN | Cooling Fan |
| COOL/FAN | Cooling Fan Relay Fuse |
| COOL/FAN | Cooling Fan Fuse |
| Relays | |
| COOL/FAN 1 | Cooling Fan Relay 1 |
| COOL/FAN 3 | Cooling Fan Relay 3 |
| COOL/FAN 2 | Cooling Fan Relay 2 |
WARNING: The terminal and harness assignments for individual connectors may vary depending on the vehicle’s equipment level, model, and market. It is recommended to refer to the fuse box diagram provided at the back of the fuse box cover for accurate information.
