Trailblazer 4X4 SERVICE LIGHT

hook
Posts: 1
Joined: Fri Dec 07, 2012 9:34 pm

Trailblazer 4X4 SERVICE LIGHT

Unread post by hook » Fri Dec 07, 2012 9:46 pm

This came on a few days ago. Every thing works except it won't shift to4L. With the engine off you can hear the shift motors run from 2H-AWD-4H then nothing when trying to go 4L. The dash switch seems to function properly what else do I need to check. Thanks for your time.

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ProTech
Posts: 651
Joined: Wed Oct 17, 2012 10:08 am

Re: Trailblazer 4X4 SERVICE LIGHT

Unread post by ProTech » Sun Dec 09, 2012 9:56 pm

Usually when it won't shift into a certain 4WD range, it is a faulty encoder motor on the side of the transfer case. Since the 'Service 4WD' light appeared, the transfer case control module would have stored a trouble code. If you can get it scanned, that would obviously help.

If the encoder motor does need replaced, it's a very easy change. You might want to inspect the wiring harness going to the encoder motor just to make sure there is no corrosion or terminal problems that would lead to another problem.
GM Dealer Technician For 18+ Years
In the automotive industry for 20+

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