In this article you will find a description of fuses and relays GMC,
with photos of block diagrams and their locations.
Highlighted the cigarette lighter fuse (as the most popular thing people look for).
Get tips on blown fuses, replacing a fuse, and more.
Instrument Panel Fuse Block
There are two instrument panel fuse blocks located behind the instrument panel on the passengerâs side of the vehicle.
Circuit Breaker | Usage |
1 | Stoplamps |
2 | Not Used |
3 | Parking Lamps |
4 | Powertrain Control Module |
5 | Auxiliary Wiring |
6 | Heater/Air Conditioning |
7 | Hazard Warning Flashers |
8 | Power Post |
9 | Courtesy Lamps |
10 | Warning Lights, Gages and Indicators |
11 | Starter |
12 | Rear Axle/Four-Wheel-Drive |
13 | Trailer Turn Signals/Hazard Warning Flashers |
14 | Radio/Chime |
15 | Daytime Running Lamps |
16 | Airbag System |
17 | Exterior/Interior Lamps |
18 | Parking Brake |
19 | Accessory Power |
20 | Ignition 4 |
21 | Sidemarker Lamps |
22 | Turn Signal/Backup Lamps |
23 | Transmission |
24 | Hydraulics/Air Brake |
A | Spare |
B | Spare |
Â
Fuse | Usage |
Blanj | Not Used |
RT PRK | Passengerâs Side Parking Lamps |
Blank | Not Used |
Blank | Not Used |
LTÂ PARK | Driverâs Side Parking Lamps |
RT REAR TRN/STOP | Passengerâs Side Rear Turn Signal/Stoplamp |
LT REAR TRN/STOP | Driverâs Side Rear Turn Signal/Stoplamp |
RADIO | Radio |
Blank | Not Used |
Blank | Not Used |
PWR WNDW | Power Windows |
Â
Relay | Usage |
ECU/PTO* | Engine Control Unit/Power Take-Off *Diesel 7.8 DURAMAXŽ |
BRK LAMP | C4/C5 Brake Lamps, C6/C7/C8 Tractor/Trailer Wiring |
DRL | Daytime Running Lamps |
IGN-4 | Ignition |
CHMSL | Center High Mounted Stop Lamp |
MRK LTS | Sidemarker and Clearance Lamps |
HTD/MIRR | Heated Mirrors |
HTR | Diesel Heated Fuel |
RT TRN TRLR | Passengerâs Side Trailer Turn Signal |
Blank | Not Used |
LT TRN TRLR | Driverâs Side Trailer Turn Signal |
Blank | Not Used |
Blank | Not Used |
Blank | Not Used |
Underhood Fuse Block
Fuse blocks are located in the engine compartment, on the passengerâs side of the vehicle.
Primary Underhood Fuse Block
Fuse | Usage |
RR DEFOG | Rear Defog |
ENG 1 | Engine 1 |
ENG 3 | Engine 3 (L18/LF6/LF8) |
PCM-B | Powertrain Control Module |
TCM | Transmissions (LF8) |
ENG 4 | Engine 4 (LMM/LF6/LF8) |
ENG 2 | Engine 2 (L18/LMM) |
HTD FUEL | Heated Fuel (LMM) |
BLANK | Not Used |
BLANK | Not Used |
NOTE 3 | Fan Relay (LMM), Emissions (L18) |
A/C COMP | Air Conditioning Compressor |
ABS 1 | Anti-lock Brake System 1 |
ABS 2 | Anti-lock Brake System 2 |
ABS 3 | Anti-lock Brake System 3 |
ENGINE | Engine |
E/A PUMP | Electronic/Automatic Pump |
HORN | Horn |
NOTE 2 | Fuel (L18/LMM), Electronic Control Module (LF6) |
NOTE 3 | Electronic Control Module (LF6) |
STUD A | Spare |
STUD B | Spare |
Â
Relay | Usage |
NOTE 1 | LMM/L18 Fuel Pump Relay |
IGN BÂ RELAY | Ignition Relay |
STARTERÂ RELAY | Starter Relay |
HORNÂ RELAY | Horn Relay |
IGN AÂ RELAY | Ignition Relay |
PTO/ECU* RELAY | Power Take-Off/Engine Control Unit (*Diesel 7.8L LF8) |
REVERSEÂ RELAY | Reverse Relay |
FANÂ RELAY | Fan Relay (LMM) |
Secondary Underhood Fuse Block
Fuse | Usage |
IGN 1 | Ignition 1 |
IGN 4 | Ignition 4 |
IGN 3 | Ignition 3 |
BATT/HAZ | Battery/Hazard Warning Flashers |
HEADLAMP | Headlamps |
LIGHTING | Interior/Exterior Lamps |
HVAC | Climate Control System |
NOTE | C4/C5 Electric Brake, C6/C7/C8 Brake Lamps |
WARNING:Â Terminal and harness assignments for individual connectors will vary depending on vehicle equipment level, model, and market.
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