Four wheel drive not working

Tiny
JASON EMERSON
  • MEMBER
  • 2010 GMC SIERRA
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 300,000 MILES
I have a automatic four-wheel drive turn knob in my truck. As I switch it from two-wheel to four-wheel drive to light switches but nothing engages are in the truck. No dash lights are on for four wheel drive. Not sure why not going for a drive or engaging.
Wednesday, January 15th, 2020 AT 7:51 AM

2 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,602 POSTS
Hello,

It sounds like you have a encoder motor that has gone out which is common. here is the transfer case wiring diagrams so you can see how the system works and which fuses to check before replacing the motor. I have also included the fuse location and the encoder motor replacement instructions in the diagrams below.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.
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Thursday, January 16th, 2020 AT 11:06 AM
Tiny
TOUGHDIVER
  • MECHANIC
  • 224 POSTS
Hi,

Jason it could be a blown fuse I'm attaching wiring schematic, fuse location and repair guides below for your reference. With a test lamp check the fuses for 12 volts on both sides of the fuse replace if blown. If the fuses are good you will need a test light to check the front axle actuator connector unplug it with key on engine not running. Check the pink wire to the black wire for 12 volts. If you have 12 volts it could be a faulty actuator. If you don't have 12 volts same connector check the pink wire to a remote ground like the frame or body if good there is a open circuit in the black wire will need repaired. If you still do not have 12 volts you an open circuit in the pink wire needs repaired. Check the transfer case encoder motor/actuator with the key on engine off unplug the connector and check for 12 volts at the red wire to remote ground if there is 12 volts could be the a faulty encoder motor. I highlighted the wires for you to test. Let us know if this info was helpful and what fixed the vehicle.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Thank you
Joe T.

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Thursday, January 16th, 2020 AT 1:01 PM

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