GMC C-Series mk3 (Third Generation; 2003 – 2009) – fuse box diagram

GMC C-Series mk3 (Third Generation; 2003 – 2009) – fuse box diagram

Year of production: 2003, 2004, 2005, 2006, 2007, 2008, 2009

Instrument Panel

There are two instrument panel fuse blocks located behind the instrument panel on the passenger’s side of the vehicle.

Fuse block 1

GMC C-Series - wiring diagram - fuse box diagram – instrument panel (fuse block 1)
GMC C-Series – wiring diagram – fuse box diagram – instrument panel (fuse block 1)
Fuse Circuits protected
RH PARK LP Right-hand Parking Lamps
LH PARK LP Left-hand Parking Lamps
RADIO U Radio
PWR WINDOW Power Windows
BRAKE ISO Brake Warning Lamp
SPARE Spare Fuse
L-RR TRUCK Left Rear Trailer Wiring
SPARE Spare Fuse
SPARE Spare Fuse
SPARE Spare Fuse
R-RR TRUCK Right Rear Trailer Wiring
SPARE Spare Fuse

Relay Circuits protected
BRAKE LAMP C4/C5 Brake Lamps, C6/C7/C8 Tractor/Trailer Wiring
IGN 4 Ignition
MARKER LP Sidemarker and Clearance Lamps
HTD FUEL LB7/LG4 Heated Fuel
AIR HTR LG4 Air Heater
ECU MAINTAIN LG4 Electronic Control Unit
DRL Daytime Running Lamps
CHMSL ISO Center High Mounted Stop Lamp
HTD MIRR Heated Mirrors
R-TRN TLR Right Trailer Turn Signal
L-TRN TLR Left Trailer Turn Signal
SPARE Spare Relay
SPARE Spare Relay
SPARE Spare Relay

Fuse block 2

GMC C-Series - wiring diagram - fuse box diagram – instrument panel (fuse block 2)
GMC C-Series – wiring diagram – fuse box diagram – instrument panel (fuse block 2)
Circuit Breaker Usage
1 Stoplamps
2 Center High Mounted Stop Lamp
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 Crank
12 Rear Axle
13 Trailer Turn Signals/Hazard Warning Flashers
14 Radio/Chime
15 Daytime Running Lamps
16 Air Bag System
17 Exterior/Interior Lamps
18 Parking Brake
19 Accessory Power
20 Ignition
21 Sidemarker Lamps
22 Turn Signal/Backup Lamps
23 Transmission
24 Chassis
A Spare
B Spare

Underhood Fuse Block

There are two underhood fuse blocks located in the engine compartment, on the
passenger’s side of the vehicle.

Primary Underhood fuse block

GMC C-Series - wiring diagram – fuse box diagram – engine compartment (primary fuse block)
GMC C-Series – wiring diagram – fuse box diagram – engine compartment (primary fuse block)
Relay Usage
NOTE 1 LG4 Powertrain Control Valve, L18/LB7 Fuel Pump, LG5 Heated Fuel
IGN B Ignition
STARTER Starter
HORN Horn
IGN A Ignition
PTO Power Take-Off
REVERSE Reverse
NEUTRAL START Neutral Start

Fuse Usage
RR DEFOG Rear Defog
ENG 1 Engine 1
ENG 3 Engine 3
PCM-B Powertrain Control Module
BLANK Empty
ENG 4 Engine 4
ENG 2 Engine 2
BLANK Empty
BLANK Empty
BLANK Empty
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 L18/LB7 Fuel, LG4 Powertrain Control Valve, LG5 Electronic Control Module
BLANK Empty
STUD A Spare
STUD B Spare

Secondary Underhood Fuse Block

GMC C-Series - wieirn gigram – fuse box diagram – engine compartment (secondary fuse block)
GMC C-Series – wieirn gigram – fuse box diagram – engine compartment (secondary 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 Comfort Control System
NOTE C4/C5 Electric Brake, C6/C7/C8 Brake Lamps

WARNING: Terminal and harness assignments for individual connectors will vary depending on vehicle equipment level, model, and market.