2021 GMC Sierra 1500 Owners Manual - Electrical System

Electrical System

The vehicle has fuses to protect against an electrical system overload. Fuses also protect power devices in the vehicle.

Replace a bad fuse with a new one of the identical size and rating.

If there is a problem on the road and a fuse needs to be replaced, there are some spare fuses and a fuse puller in the left instrument panel fuse block. The

same amperage fuse can also be borrowed.

Choose some feature of the vehicle that is not needed to use and replace it as soon as possible.

An electrical overload may cause the lamps to go on and off, or in some cases to remain off. Have the headlamp wiring checked right away if the lamps go on and off or remain off.

If the wiper motor overheats due to heavy snow or ice, the windshield wipers will stop until the motor cools and will then restart.

Although the circuit is protected from electrical overload, overload due to heavy snow or ice may cause wiper linkage damage. Always clear ice and heavy snow from the windshield before using the windshield wipers.

If the overload is caused by an electrical problem and not snow or ice, be sure to get it fixed.

The wiring circuits in the vehicle are protected from short circuits by a combination of fuses and circuit breakers. This greatly reduces the chance of damage caused by electrical problems.

See Accessories and Modifications 0 321 and

General Information 0 320.

To check a fuse, look at the silver-colored band inside the fuse. If the band is broken or melted, replace the fuse. Be sure to replace a bad fuse with a new one of the identical size and rating.

Fuses of the same amperage can be temporarily borrowed from another fuse location, if a fuse goes out. Replace the fuse as soon as possible.

If the vehicle has a diesel engine, see the Duramax diesel supplement.

The engine compartment fuse block is in the engine compartment, on the passenger side of the vehicle.

Lift the cover to access the fuse block.

A fuse puller is available in the left instrument panel end cap.

The vehicle may not be equipped with all of the fuses, relays, and features shown.

Fuses Usage

High-beam left

High-beam right

Fuses Usage

Headlamp left

Headlamp right

Fuses Usage

Auxiliary underhood electrical center

Cooling fan motor left

Active fuel management 2

68 –

69 Starter Pinion (LD) / Starter Motor (HD Gas)

Cooling fan

Cooling fan right

Trailer stop/turn lamp left

TIM

DEFC

Electric RNG BDS

Engine control module

Auxiliary battery

Cabin cooling pump

Trailer stop/turn lamp right

TIM

Fuses Usage

FTZM

Trailer brake

ENG

Engine control module

Injector B even

O2 B sensor

O2 A sensor

Injector A odd

Engine control module throttle control

Cool fan clutch

Relays Usage

5 Headlamp

18 DC/AC inverter

23 Rear window defogger

Parking lamp

Run/Crank

43 Second fuel pump

59 A/C clutch

Relays Usage

64 Starter Motor (LD & HD DSL) / Cool Fan Clutch (HD Gas)

70 Starter Pinion (LD) / Starter Motor (HD Gas)

77 Powertrain

The left instrument panel fuse block access door is on the driver side edge of the instrument panel.

The vehicle may not be equipped with all of the fuses, relays, and features shown.

Pull off the cover to access the fuse block. A fuse puller is available in the left instrument panel end cap.

The vehicle may not be equipped with all of the fuses, relays, and features shown.

Fuses Usage

F1 Rear heated seats left/right

F3 –

F4 –

F5 Spare/MFEG

F6 Heated and ventilated seats left/right

F8 –

Fuses Usage

F20 Endgate

F22 Rear sliding window

F23 –

F24 –

F25 –

F26 –

F27 –

F9 Passive entry passive start/ Spare

F10 –

Circuit Breakers

CB1 –

Usage

F11 –

F12 Passenger power seat

F13 Export power take off/ Special equipment option 1

F14 –

F15 –

F16 AMP

F17 –

F18 –

Relays Usage

K1 Rear sliding window open

K2 Rear sliding window close

K3 MFEG major 1

K4 MFEG minor 1

K5 MFEG minor 2

K6 MFEG major 2

K7 –

K8 –

The right instrument panel fuse block access door is on the passenger side edge of the instrument panel.

Pull off the cover to access the front of the fuse block.

To access the back of the fuse block:

Push the tab at the top of fuse block down.

Pull the top of the fuse block outward.

Reverse Steps 1–2 to reinstall.

Back

The vehicle may not be equipped with all of the fuses, relays, and features shown.

Fuses Usage

F1 Right doors

F2 Left doors

F3 Universal garage door opener

F4 –

F5 –

F6 Front blower

F8 Lumbar switch

F10 Body control module 6/ Body control module 7

F11 Seat/Column lock module

F12 Body control module 3/ Body control module 5

F14 Mirrors/Windows module

F17 Steering wheel controls F18 Video processing module/

Obstacle detection

F19 DLIS

F20 Ventilated seats

F21 NOT R/C

F22 Heated steering wheel

Fuses Usage

F23 MISC R/C

F24 Instrument panel cluster ignition/Overhead

F25 Heating, ventilation, and air conditioning ignition/ Heating, ventilation, and air conditioning auxiliary

F26 USB ports/Special equipment option retained accessory power

F27 Accessory power outlet/ retained accessory power

F28 Accessory power outlet/ Battery

F30 Sensing and diagnostic module/Parking brake

F31 Body control module 4 F32 Special equipment option/

Data link connection

F33 Body control module 8

F34 Cargo lamp

F40 CGM

F41 Infotainment 1

Fuses Usage

F42 TCP

Circuit Breakers

Usage

F43 –

F44 Active vibration management

F45 Body control module 2 F46 Heating, ventilation, and

air conditioning/Battery 1

F47 Instrument panel cluster/ Battery

F48 Transmission control module

F49 Body control module 1

F50 –

F51 Battery 1

F52 Battery 2

F53 –

F54 Sunroof

F55 Driver power seat

F56 DC DC TRANS 1

F57 DC DC TRANS 2

F58 Infotainment 2

Accessory power outlet 2

Accessory power outlet 1/ Cigarette Lighter

Accessory power outlet 3

Accessory power outlet 4

Relays Usage

K1 Run/Crank

K2 Retained accessory power/ Accessory 1

K4 Retained accessory power/ Accessory 2

K5 –

manufacturer.