In this article you will find the GMC T-Series (T6500, T7500, T8500) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 fuse box outline, information on the location of the fuse boxes inside the vehicle and the allocation of each fuse (fuse layout) and relay.
The cigar lighter (socket) fuse on the GMC T6500, T7500, T8500 is fuse #2 in the instrument panel fuse box.
Fuse box location
Instrument Panel Fuse Block
It is located on the top of the instrument panel on the passenger’s side of the vehicle.
Maxi-Fuse Block
The maxi-fuse block outside of the cab on the driver’s side of the vehicle.
Relay Blocks
There are four relay blocks in your vehicle
A – Relay Block A
B – Relay Block B
C – Relay Block C
D – Relay Block D
Fuse box diagrams
Instrument Panel
Assignment of the fuses in the Instrument Panel fuse box
| № | Circuits Protected |
|---|---|
| 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) |
Assignment of the fuses in the Maxi-Fuse Block
| Name | Circuits/Circuit Breakers Protected |
|---|---|
| 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 |
Relay Block A
| Relay Block A | Usage |
|---|---|
| 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) |
Relay Block B
| Relay Block B | Usage |
|---|---|
| 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) |
Relay Block C
| Relay Block C | Usage |
|---|---|
| 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 |
Relay Block D
| Relay Block D | Usage |
|---|---|
| 1 | Neutral (Medium Duty Transmission) |
| 2 | Back-up Lamp (Reverse) (Medium Duty Transmission) |
