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

RR WiperNot Used
SEO ACCYSpecial Equipment Option Accessory
WSWPRWindshield Wipers
TBC ACCYTruck Body Controller Accessory
IGN 3Ignition, Heated Seats
4WDFour-Wheel Drive System, Auxiliary Battery
HTR A/CClimate Control System
LOCK (Relay)Power Door Lock Relay (Lock Function)
HVAC1Climate Control System
LDOORDriver’s Door Harness Connection
CRUISECruise Control, Power Take Off (PTO)
UNLOCK (Relay)Power Door Lock Relay (Unlock Function)
BRAKEAnti-Lock Brake System
DRIVER UNLOCKPower Door Lock Relay (Driver’s Door Unlock Function)
TBC IGN 0Truck Body Controller
VEH CHMSLVehicle and Trailer High Mounted Stoplamp
LT TRLR ST/TRNLeft Turn Signal/Stop Trailer
LTTRNLeft Turn Signals and Sidemarkers
VEH STOPVehicle Stoplamps, Brake Module, Electronic Throttle Control Module
RT TRLR ST/TRNRight Turn Signal/Stop Trailer
RTTRNRight Turn Signals and Sidemarfcers
BODYHarness Connector
DDMDriver Door Module
AUX PWR 2Not Used
LOCKSPower Door Lock System
ECCNot Used
TBC 2CTruck Body Controller
FLASHFlasher Module
CB LT DOORSLeft Power Windows Circuit Breaker
TBC 2BTruck Body Controller
TBC 2ATruck 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

SEOSpecial Equipment Option
TRAILERTrailer Brake Wiring
UPFITUptitter (Not Used)
SL RIDERide Control Harness Connection
HDLR 2Headliner Wiring Connector
BODYBody Wiring Connector
DEFOGRear Defogger Relay
HDLNR 1Headliner Wiring Connector 1
CB SEATDriver and Passenger Seat Module Circuit Breaker
CB RT DOORRight Power Windows Circuit Breaker
INFOInfotainment 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

GLOW PLUGDiesel Glow Plugs and Intake Air Heater
CUST FEEDGasoline Accessory Power
STUD #1Auxiliary Power (Single Battery and Diesels Only)/ Dual Battery (TP2) Do not install fuse.
MBECMid Bussed Electrical Center Power Feed, Front Seats, Right Doors
BLOWERFront Climate Control Fan
LBECLeft Bussed Electrical Center, Door Modules, Door Locks, Auxiliary Power Outlet-Rear Cargo Area and Instrument Panel
STUD 2Accessory Power/Trailer Wiring Brake Feed
ABSAnti-Lock Brakes
VSES/ECASVehicle Stability
IGN AIgnition Power
IGN BIgnition Power
LBEC 1Left Bussed Electrical Center, Left Doors, Truck Body Controller, Flasher Module
TRL PARKParking Lamps Trailer Wiring
RR PARKRight Rear Parking and Sidemarker Lamps
LR PARKLeft Rear Parking and Sidemarker Lamps
PARK LPParking Lamps Relay
STARTERStarter Relay
INTPARKInterior Lamps
STOP LPStoplamps
TBC BATTTruck Body Controller Battery Feed
SEO B2Off-Road Lamps
4WSVent Solenoid Canister/Quadrasteer Module Power
AUX PWRAuxiliary Power Outlet — Console
IGN 1Ignition Relay
PCM 1Powertrain Control Module
ETC/ECMElectronic Throttle Control, Electronic Brake Controller
IGNEInstrument Panel Cluster, Air Conditioning Relay, Turn Signal/Hazard Switch, Starter Relay
RTDRide Control
TRL B/UBackup Lamps Trailer Wiring
PCM BPowertrain Control Module, Fuel Pump
F/PMPFuel Pump (Relay)
B/U LPBack-up Lamps, Automatic Transmission Shift Lock Control System
RR DEFOGRear Window Defogger
HDLP-HIHeadlamp High Beam Relay
O2BOxygen Sensors
SIRSupplemental Inflatable Restraint System
FRT PARKFront Parking Lamps, Sidemarker Lamps
DRLDaytime Running Lamps (Relay)
SEO IGNRear Defog Relay
TBC IGN1Truck Body Controller Ignition
HI HDLP-LTHigh Beam Headlamp-Left
LH HIDNot Used
DRLDaytime Running Lamps
IPC/DICInstrument Panel Cluster/Driver Information Center
HVAC/ECASClimate Control Controller
CIGLTRCigarette Lighter
HI HDLP-RTHigh Beam Headlamp-Right
HDLP-LOWHeadlamp Low Beam Relay
A/C COMPAir Conditioning Compressor
A/C COMPAir Conditioning Compressor Relay
RADIOAudio System
SEO B1Mid Bussed Electrical Center, Rear Heated Seats, HomeLink
LO HDLP-LTHeadlamp Low Beam-Left
BTSIBrake Transmission Shift Interfock System
CRANKStarting System
LO HDLP-RTHeadlamp Low Beam-Right
BTSIBrake Transmission Shift Interlock System
CRANKStarting System
LO HDLP- RTHeadlamp Low Beam-Right
FOG LPFog Lamp Relay
FOG LPFog Lamps
HORNHorn Relay
W/S WASHWindshield Washer Pump Relay
W/S WASHWindshield Washer Pump
INFOOnStar/Rear Seat Entertainment
RADIO AMPRadio Amplifier
RH HIDNot Used
EAPNot Used
TRECAll-Wheel Drive Module
SBASupplemental 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.

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

COOL/FANCooling Fan
COOL/FANCooling Fan Relay Fuse
COOL/FANCooling Fan Fuse
COOL/FAN 1Cooling Fan Relay 1
COOL/FAN 3Cooling Fan Relay 3
COOL/FAN 2Cooling 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.

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