Categories: GMC

GMC Topkick (2003-2010) fuses and relays

The medium duty truck GMC Topkick was produced from 2003 to 2010. In this article, you will find fuse box diagrams of GMC Topkick 2006, 2007, 2008 and 2009, get information about the location of the fuse panels inside the car, and learn about the assignment of each fuse (fuse layout) and relay.

Fuse Layout GMC Topkick 2003-2010

Contents

Table of Contents

Fuse box location

Instrument panel fuse box

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

Engine compartment fuse box

Both underhood fuse blocks are located in the engine compartment, on the passenger’s side of the vehicle.
To access the fuse blocks, gently squeeze both sides of the cover to unlatch the tabs at the top. Then, unsnap both attachments at the bottom and remove the cover.

Fuse box diagrams

2006

Primary Underhood Fuse Block

Assignment of the fuses in the Primary Underhood Fuse Block (2006)

Name	Usage
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

Assignment of the fuses in the Secondary Underhood Fuse Block (2006)

Name	Usage
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, box1

Assignment of the fuses in the Instrument panel fuse box 1 (2006)

Circuit Breaker	Usage
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

Instrument panel, box 2

Assignment of the fuses in the Instrument panel fuse box 2 (2006)

Name	Usage
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®
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

2007

Primary Underhood Fuse Block

Assignment of the fuses in the Primary Underhood Fuse Block (2007)

Name	Usage
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

Assignment of the fuses in the Secondary Underhood Fuse Block (2007)

Name	Usage
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, box1

Assignment of the fuses in the Instrument panel fuse box 1 (2007)

Circuit Breaker	Usage
1	Stoptamps
2	Center High-Mounted Stoplamp
3	Parlang 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	Parlang 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

Instrument panel, box 2

Assignment of the fuses in the Instrument panel fuse box 2 (2007)

Name	Usage
Blank	Not Used
RT PRK	Passenger’s Side Parking Lamps
Blank	Not Used
Blank	Not Used
LT PARK	Driver’s Side Pairing Lamps
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
PWRWNDW	Power Windows

Relay
ECU/PTO	Engine Control Unit/Power Take-Off ‘Diesel 7.8 DURAMAX
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
MRKLTS	Sidemarker and Clearance Lamps
HTD/MIRR	Heated Mirrors
HTR	Diesel Heated Fuel
RT TRN TRLR	Passenger’s Side Trailer Turn Signal
Blank	Not Used
LT TRN TRLR	Driver’s Side Trailer Turn Signal
Blank	Not Used
Blank	Not Used
Blank	Not Used

2008, 2009

Primary Underhood Fuse Block

Assignment of the fuses in the Primary Underhood Fuse Block (2008, 2009)

Name	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

Relay
NOTE 1	LMM/L18 Fuel Pump Relay
IGN B RELAY	Ignition Relay
STARTER RELAY	Starter Relay
HORN RELAY	Horn Relay
IGN A RELAY	Ignition Relay
PTO/ECU RELAY	Power Take-Off/Engine Control Unit (*Diesel 7.8L LF8)
REVERSE RELAY	Reverse Relay
FAN RELAY	Fan Relay (LMM)

Secondary Underhood Fuse Block

Assignment of the fuses in the Secondary Underhood Fuse Block (2008, 2009)

Name	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

Instrument panel, box 1

Assignment of the fuses in the Instrument panel fuse box 1 (2008, 2009)

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/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

Instrument panel, box 2

Assignment of the fuses in the Instrument panel fuse box 2 (2008, 2009)

Name	Usage
Blank	Not Used
RT PRK	Passenger’s Side Parking Lamps
Blank	Not Used
Blank	Not Used
LT PARK	Driver’s Side Parking Lamps
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
PWR WNDW	Power Windows

Relay
ECU/PTO	Engine Control Unit/Power Take-Off “Diesel 7.8 DURAMAX®
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	Passenger’s Side Trailer Turn Signal
Blank	Not Used
LT TRN TRLR	Driver’s Side Trailer Turn Signal
Blank	Not Used
Blank	Not Used
Blank	Not Used