02 Tahoe Transfer Case Shift Motor

Discussion in 'GM Powertrain' started by mortalwombat, Apr 24, 2009.

  1. mortalwombat

    mortalwombat New Member

    I have an '02 Tahoe Z21. Recently, I noticed a bit of noise when driving 65 or 70 down the highway. It turned out to be the front driveshaft clanking. The front U-Joint on that was worn, so I replaced that, which stopped the clanking.

    However, shouldn't the driveshaft not be turning when in 2 wheel drive? There is a motor, which I assume to be a shift motor, that you can hear turning when you shift from 2 to 4 and back to 2. Is this is the shift motor that is supposed to disengage the front driveshaft, but it's just slipping and not pulling the transfer case out of 4? Is there any way to test this without buying a new motor just to find it's not the problem?

    A mechanic told me that the transfer case stays engaged 24/7, but that seems bogus to me. It sound like a lot of wear and tear for a model vehicle that seems to spend more time on-road than off.
  2. Jacqson

    Jacqson Rockstar 100 Posts

    Your mechanic is right. Any truck with the Auto 4WD feature has the NVG 246 Transfer case and the front shaft turns all the time the vehicle is in motion. The shift motor your talking about disengages the front end but the front Drive shaft still turns.
  3. mortalwombat

    mortalwombat New Member

    Thanks for the reply. Earlier today I climbed underneath and had a listen to what I had assumed was the shift motor as someone shifted in and out of 4WD. It sounded like it was slipping when going into 2WD but sounded like it was grabbing going into 4WD.

    What you are saying is intresting, and you may very well be right. But if that is the case, what is this? http://www.1aau.com/1A/4WDve/Chevrolet/Tahoe/1AFWM00002/1094257/
    It looks to be the same part I was listening too. If it doesn't shift the transfer case from 2WD to 4WD, what does it do? Just shift from 4 hi to 4 low?

  4. Jacqson

    Jacqson Rockstar 100 Posts

    Since your front driveshaft turns all the time which means it's engaged like it is in 4WD all the time, I"d have to guess that part shifts the TC from Hi range 4WD to Low range 4WD. The transfer case works like a full time 4WD and the only thing that keeps it in 2WD is that there is a similar type of switch on the diff that disengages it. That's my best guess.

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