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tristan, ASE MASTER
Category: GM
Satisfied Customers: 1610
Experience:  8yrs. exp. ASE MASTER
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2006 GMC Sierra 1500: Crew Cab..4 wheel drive engaging..activating

Resolved Question:

I have a 2006 GMC Sierra 1500 Crew Cab Z-71. My "Service 4WD" has alarmed a couple of times and I have cleared it and not had any issues. Since then, I had an issue with theXXXXXengaging without activating it with the 4WD button. I have started my truck and it wil be in 4WD low or the light indicating 2WD or 4WD will not light up at all. I can kill the ignition or switch to 2WD and it works fine, but this has also happened a couple of times. What could be the problem, and is there something I can do or check before bringing it in to the shop?
Submitted: 8 years ago.
Category: GM
Expert:  tristan replied 8 years ago.

the only problem i have seen on these is the prop shaft harness key some water in if and need to be replaced, this is the most common failure for a intermittent concern. locate C151 by the fuse block and inspect for water there and at the prop shaft speed sensor on the transfer case. im sending the wire harness part number also. with 2 wheel steer 15224663, without 4 wheel steer 15832722. good luck.and please accept my answer. thanks T-MAN



Object Number: 814636  Size: LF
Click here for detailed picture of above image.

(1)Fuse Block - Underhood
(2)C153 - Engine Harness to Transfer Case Harness
(3)C150 - Transfer Case Harness to Axle Jumper Harness
(4)Transfer Case Harness
(5)C151 - I/P Harness to Automatic Transfer Case Harness (NP8/NP1)
(6)C154 - I/P Harness to Automatic Transfer Case Harness (NP8/NP1)
(7)Power Take-Off (PTO) Relay


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