Service 4WD light

Hello... Have a 2006 Chevy Tahoe with the information panel displaying the "Service 4WD" message. Statistically speaking, what are the most
common reasons for this message to be displayed? I'd like to investigate before the winter weather hits and figured I'd start here, as I'm sure there are others on this forum who have experienced this issue...
Thanks much!
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"Raymond Sirois" wrote in message

Mine was still under warranty, so I don’t really know what they fixed.
John
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Raymond Sirois wrote:

Pull the codes from the ECM and BCM and it will point you in the correct direction.
The common areas for problems are the controller, the switch assembly and the shift motor on the T-Case. With the codes and some simple tests you can pinpoint the problem real fast rather than just swapping some expensive parts.
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On Mon, 16 Sep 2013 21:23:25 -0500, Raymond Sirois

The replies you received already match my own observations, with a Tahoe 2000 and a Tahoe 2007. The good news is that the problem is very commonly the wiring harnesses or the controller. There are also contact switches that signal when a gear transfer completed successfully, with the default position being "when in doubt, do nothing:" if one contact switch is faulty, the controller disables itself.
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On Thu, 26 Sep 2013 12:08:11 -0600, Desertphile wrote:

Oddly enough this is the first reply I've seen to my query. From your response it looks to me as if they were basically along the lines of check all the connections make sure they're tight, and check the wiring for breaks in the insulation?
Ray
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Raymond Sirois wrote:

"Raymond Sirois" wrote in message > > > >Hello... Have a 2006 Chevy Tahoe with the information panel displaying > >the "Service 4WD" message. Statistically speaking, what are the most > >common reasons for this message to be displayed? I'd like to investigate > >before the winter weather hits and figured I'd start here, as I'm sure > >there are others on this forum who have experienced this issue... > > > >Thanks much! When I had this problem, it turned out to be a bad controller or switch. Mine was still under warranty, so I don’t really know what they fixed.
John

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On Thu, 26 Sep 2013 22:54:40 -0500, Raymond Sirois

Your NNTP server may not have received the replies. As someone else wrote, he had your problem and the faulty controller was replaced since it was still under warranty. The mid-age Tahoes for some stupid reason were made with wire harness connectors that did not seal out moisture very well. (Same with head light sockets, tail light sockets, and assorted connectors.)

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