2005 GMC Yukon Service 4 wheel drive is lit.

2005 GMC YUKON
48,000 MILES • V8 • 4WD • AUTOMATIC
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GAUBERG
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I've had this truck to the dealer before for this same problem. Ever since I purchased this truck has had this problem. I'm the only owner! When I start engine the message comes up, but all the lights on the left side of dash go out before you can push them. So I know the bulbs are good. It just won't let me shift into 4wh or 4wl.
There was a time when I could restart truck, and lights would stay lit. At least whatever range you were in, but I have no LED's lit now. What could be wrong?
Feb 1, 2010 at 7:46 PM
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FACTORYJACK
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The message that comes up is 'service 4wd'? There are several possibilities of faults, and several bulletins as well. Reallistically, I would need a trouble code to go off of. I did a little research in GM service info, and some codes disable the switch LED's, and some disable shifting of transfer case. The restarting and getting the switch back may just be that the fault was intermittent in nature. If cycling the ignition is not bringing it back, it may be a hard failure at this point. It could be the encoder, the transfer case control module, switch, or circuitry wiring. A fault code would narrow it down a bit, if not significantly. I am not sure if a parts house like autozone can interrogate the transfer case for codes, since it is not emissions related.
Feb 2, 2010 at 10:59 PM