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Service 4WD...Need help

Discussion in 'General Chevy & GM Tech Questions' started by Dented Fender, Dec 29, 2010.

  1. Dented Fender

    Dented Fender New Member

    Newbie here, just joined about an hour ago after reading quite a few interesting posts... i figureed I'd ask a question and see if i can get some useful input!
    I drive a 1999 silverado 1500, and believe it or not; I am having problems with my 4 wheel drive. First off, I am 100% positave that it has nothing to do with the push button switch on the dash. Anyways here's the deal. Sometimes (maybe 30% of the time) when I start my pickup the amber colored light on the 2hi button is lit up, and I am able to switch between 2hi and auto 4wd. However, I am not able to get it into 4hi. The light on 4hi just flashes at me about 5 or 6 times when i press it while 2hi is lit up, then 2hi flashes 5 or 6 times then stays solid. The service 4wd message does not show up.
    The other 70% of the time or so is a differnt story. As soon as i turn on my key on, the light on the auto 4wd button flashs for a fraction of a second and then i can hear relays behind the dash start to click. they click about 10 times and its almost to a rythem (im serious). Then as soon as i start my pickup they start clicking again, and then service 4wd comes on.
    I recorded videos and posted them on youtube. The first one is a video of when i am able to switch from 2hi to auto. this is the link http://www.youtube.com/watch?v=NApnkiqQMz4. The second video is when the service 4wd message comes on and you can hear the strange relay clicks. there's that link http://www.youtube.com/watch?v=zEGWzBybvx4


    Can somebody please let me know if they have heard of the same problem. I really dont want to go to the bank and refinance my pickup to buy a new TCCM and a new encoder motor or a new transfer case if i dont have to. Thanks for any help
    Last edited: Dec 29, 2010

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