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Tranny wont shift

Discussion in 'GM Powertrain' started by 88burban, Mar 17, 2008.

  1. 88burban

    88burban New Member

    Ok first off i got an 88 suburban 6.5 diesel 4x4 automatic and my tranny wont get out of first gear. When i bought the truck there was a problem with the tranny but i was able to get out of first gear and into second. One day i decided to take it to a car wash and i get on the road and cant get out of first. It just happened overnight. Now when i got the truck it had been sitting for 2 years. When i drove it I would have to pretty much redline the rpm, let off the gas, then it would slip into second gear. A year later and it doesnt switch at all. I dont know anything about trannys so any help is greatly appreciated.
  2. GaryL

    GaryL Epic Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    See if you can find the vacuum modulator (I think yours has one) on the passenger side of the transmission. Make sure the vacuum line is hooked up at both ends and there are no holes in the line. If everything is hooked up fine, the modulator may have gone bad.

    Have you tried shifting it manually?

    It should look like this:

    [​IMG]
  3. 88burban

    88burban New Member

    Thanks im gonna go look at that in a little bit. I have tried doing it manualy but didnt have any luck. Thanks alot for the picture refrence, that will help alot
  4. 88burban

    88burban New Member

    I checked the vacuum modulator and the hose was still connected. Im gonna replace it but does any one know where i can get one. I tried searching for one but cant seem to find one
  5. GaryL

    GaryL Epic Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    Looks like O'reilly has them for around $20.

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