The GMC Topkick, a medium duty truck, was made from 2003 to 2010. In this article, you’ll find diagrams showing where the fuse boxes are located in the 2006, 2007, 2008, and 2009 models. It explains which fuses and relays are for what parts of the vehicle.
Table of Contents
Fuse Box Location
Instrument panel
There are two fuse boxes inside the dashboard on the passenger’s side of the vehicle.
Engine compartment
Both fuse boxes under the hood are on the passenger side of the car’s engine area. To get to them, gently press both sides of the cover to release the tabs at the top. Then, unclip both connections at the bottom and take off the cover.
[2006]
Primary Underhood Fuse Block
Name
Description
RR DEFOG
Rear Defog
ENG 1
Engine 1
ENG 3
Engine 3
PCM-B
Powertrain Control Module
BLANK
Not Used
ENG 4
Engine 4
ENG 2
Engine 2
HTD FUEL
Heated Fuel
BLANK
Not Used
BLANK
Not Used
O2A
Emissions
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 Fuel, LG4 Powertrain Control Valve, LG5 Electronic Control Module
NOTE 3
L18 Fuel, LG4 Powertrain Control Valve, LG5 Electronic Control Module
STUD A
Spare
STUD B
Spare
Relay
NOTE 1
LG4 Powertrain Control Valve, L18 Fuel Pump, LG5 Heated Fuel
IGN B
Ignition
STARTER
Starter
HORN
Horn
IGN A
Ignition
PTO/ECU
Power Take-Off/Engine Control Unit “Diesel 7.8L DURAMAX
REVERSE
Reverse
NEUTRAL START
Neutral Start
Secondary Underhood Fuse Block
Name
Description
IGN 1
Four-Wheel Drive Module
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
Instrument panel
Fuse box 1
Circuit Breaker
Description
1
Stoplamps
2
Center High-Mounted Stoplamp
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/lnterior 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
Fuse box 2
Name
Description
HTD/MIRR
Heated Mirrors
Blank
Not Used
RT TRN TRLR
Passenger’s Side Trailer Turn Signal
Blank
Not Used
LT TRN TRLR
Driver’s Side Trailer Turn Signal
Blank
Not Used
BRK
Brake Warning Lamp
RT PRK
Passenger’s Side Parking Lamps
Blank
Not Used
Blank
Not Used
Blank
Not Used
LT PARK
Driver’s Side Parking Lamps
Blank
Not Used
RT REAR TRN/STOP
Passenger’s Side Rear Turn Signal/Stoplamp
LT REAR TRN/STOP
Driver’s Side Rear Turn Signal/Stoplamp
RADIO
Radio
Blank
Not Used
Blank
Not Used
Blank
Not Used
PWR WNDW
Power Windows
Relay
ECU/PTO
Engine Control Unit/Power Take-Off “Diesel 7.8 DURAMAX®
Tom Smith is a passionate car mechanic and automotive enthusiast, specializing in the intricate world of car fuse boxes. With years of hands-on experience under the hood, he has earned a reputation as a reliable expert in his field. As the founder and content creator of the popular blog website 'carsfuse.com,' Tom has dedicated himself to sharing his extensive knowledge of car fuse boxes and electrical systems with the world.
