GMC T-Series mk2 (1999 – 2002) – fuse box diagram
Year of production: 1999, 2000, 2001, 2002
Instrument Panel Circuit Breaker and Relay Blocks
These circuit breaker and relay blocks are located on top of the instrument panel on the passenger’s side of the cab.
| Number | Circuits Protected |
| 1 | Ignition Switch |
| 2 | Cigarette Lighter, Radio |
| 3 | Engine ECU (TICS) |
| 4 | Glow Relay, ESC, EVRV, Gov. Mod., Engine ECM (GAS) |
| 5 | Checker Connector (TICS), ALDL Connector |
| 6 | Meter, D.R.A.B., Warning Lamp, Engine Stop Relay, Ignition Relay, Blower Motor Relay, Auxiliary Relay, Power Window Relay, Air Intake Relay, Fuel Filter Relay, Intermittent Relay |
| 7 | Dome Lamp, Horn, Electric Parking Brake, Radio (Back-Up), MD Automatic Transmission VIM, Engine ECM (GAS), Fuel Pump, Fuel Filter |
| 8 | Power Window |
| 9 | Anti-Lock Braking System, Exhaust Brake, Back-Up Lamps, M.F.A.M., Electric Parking Brake, Air Suspension Dump, Differential Lock, Air Dry and Moisture Ejector Heater, MD Automatic Transmission, Ignition Coil, Injector, Fuel Tank Module and Pump, Generator (F), Engine ECU (TICS), Checker Connector (TICS) |
| 10 | Checker Connector (TICS) |
| 11 | Trailer Turn (LH) Lamp, ID Lamp, Marker Lamp, Clearance Lamp |
| 12 | Auxiliary (Ignition ON) |
| 13 | Auxiliary (Battery Direct) |
| 14 | Headlamp (LH) |
| 15 | Headlamp (RH) |
| 16 | Headlamp |
| 17 | Engine Stop Actuator |
| 18 | M.F.A.M., Hydraulic Brake Motor |
| 19 | Taillamp, Light MIR, Illumination Lamp |
| 20 | Cool Condenser Fan Motor, Cooler Compressor |
| 21 | Wiper Motor, Washer Motor |
| 22 | Heated Mirror, 2-Speed Axle Motor, 2-Speed Axle Relay |
| 23 | Hydraulic Brake Relay, M.F.A.M., Flasher Unit |
| 24 | Blower Motor, Air Conditioner Relay |
| 25 | Trailer Turn (RH) Lamp, Flasher Unit |
| 26 | Power Post (Consent) |
Maxi-Fuse Block
Maxi-Fuse block is located outside of the cab at the rear, on the driver’s side.
| Name | Circuits/Circuit Breakers Protected |
| ST/TURN/HAZ | Stoplamp, Turn Signals/Hazard Warning Flashers, Fuel, Ignition Relay (Gasoline Engines) |
| IGN SW3 | Air Conditioner, Axle, Chassis |
| INT/EXT LIGHTS | Parking 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 | ABS Module |
| ELECT TRANS | Ignition Relay (Diesel Engines) |
| PARK BRAKE | Parking Brake Motor |
| BLOWER HORN | Blower, Horn, Cigarette Lighter, Auxiliary |
| TRAILER ABS | Trailer ABS System, Trailer Stoplamps |
| PWR WDO/LOCKS | Power Windows, Power Door Locks |
WARNING: Terminal and harness assignments for individual connectors will vary depending on vehicle equipment level, model, and market.