Looking for fuse box information for the GMC T-Series (T6500, T7500, T8500) ? This article covers model years 2003, 2004, 2005, 2006, 2007, 2008 and 2009 , showing fuse box diagrams , explaining the locations of the fuse panels , and detailing the fuse and relay assignments so you can quickly identify what powers what without digging through guesswork.
It is located on the top of the instrument panel on the passenger’s side of the vehicle.
There are four relay blocks in your vehicle
A – Relay Block A
The maxi-fuse block outside of the cab on the driver’s side of the vehicle.
Fuse Data
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Assignment of the fuses in the Passenger Compartment fuse box
Fuse Data
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No. Description 1 Ignition Switch 2 Cigarette Lighter 3 ECM Ignition 1 4 Truck Body Controller 5 ALDL Connector 6 Warning Lamp, Ignition Relay, Blower Motor, Motor Relay, Auxiliary Relay, Power Window Relay, INT Relay 7 Room Lamp, Horn, Electric Parking Brake, Radio Back Up, Rear Body Dome Lamp 8 Power Window 9 Exhaust Brake Back Up, Air Suspension Dump, Differential Lock, Air Dryer, Moisture Ejection Heater, Electric Air Compressor, Power Take Off 10 ECM Ignition Power 11 Trailer Turn (LH) Lamp 12 Auxiliary (Ignition ON) 13 Auxiliary (Battery Direct) 14 Headlamp (LH) 15 Headlamp (RH) 16 Headlamp 17 Heated Fuel 18 Meter Truck Body Controller 19 ID Lamp, Marker Lamp, Tail Lamp, Lighted Mirror, Illumination Lamp 20 Cool Condenser Fan Motor, Cooler Compressor 21 Wiper Motor, Washer Motor 22 Heated Mirror, Two-Speed Axle Relay 23 Empty 24 Blower Motor, Air Conditioner Relay 25 Trailer Turn (RH) Lamp, Flasher Unit 26 Power Post (Consent)
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Assignment of the relays in the Relay Block A
Fuse Data
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No. Description 1 Power Window 2 Back Lamp (Reverse) 3 High Beam 4 Lighting 5 Lighting (Low, High) 6 Trailer Turn Signal (Left Headlamp) 7 Tail Lamp 8 Marker Lamp 9 Trailer Turn Signal (Right Headlamp)
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Assignment of the relays in the Relay Block B
Fuse Data
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No. Description 1 Air Conditioning Condenser (If Equipped) 2 Air Conditioning Compressor (If Equipped) 3 Heater Fan 4 Ignition (Accessory) 5 Ignition 1 6 Ignition 2 7 Auxiliary 8 Horn 9 Ignition 3 10 Dome Lamp (If Equipped) 11 Exhaust Brake (If Equipped) 12 Power Take Off Control (If Equipped)
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Assignment of the relays in the Relay Block C
Fuse Data
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No. Description 1 Parking Brake 2 Daytime Running Lamps (DRL) On (Engine Run) 3 Daytime Running Lamps (DRL) Off (Parking) 4 Parking Lamps/Daytime Running Lamps (DRL) 5 Fuel Filter (Heated Fuel) 6 Stop Lamp
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Assignment of the relays in the Relay Block D
Fuse Data
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No. Description 1 Neutral (Medium Duty Transmission) 2 Back-up Lamp (Reverse) (Medium Duty Transmission)
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Assignment of the fuses in the Maxi-Fuse Block
Fuse Data
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Short-Code Description ST/TURN/HAZ Stoplamp, Turn Signals/Hazard Warning Flashers IGN SW3 Air Conditioner, Axle, Chassis INT/EXT LIGHTS Parldng Lamps, Dome Lamp, Instrument Panel Lights HEAD LAMP Headlamps, Daytime Running Lamps AUX WRG Auxiliary, Parking Brake IGN SW1 Ignition Switch, Washer/Wiper, Crank, Radio HYD PUMP Hydraulic Brake, Brake Pump Motor ABS Anti-Lock Brake System Module ELECT TRANS Ignition Relay PARK BRAKE Parking Brake Motor BLOWER HORN Blower, Horn, Cigarette Lighter, Auxiliary TRAILER ABS Trailer Anti-Lock Brake System, Trailer Stoplamps PWR WDO/LOCKS Power Windows, Power Door Locks
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