truck won't move.

Discussion in 'GM Powertrain' started by yotaboy81, Nov 9, 2010.

  1. yotaboy81

    yotaboy81 New Member

    I have a 98 GMC K2500 4wd. 7.4l. The vehicle won't move when in d or reverse. and when i put in Park there is a clanking/grinding noise. i used the auto 4wd a couple of days ago. and then it stopped moving on my way to work. where should i start? is the transfer case stuck in neutral. please help
  2. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    Sure sounds like the transfer case is stuck in neutral to me. The grinding noise you hear is the parking pawl trying to engage on the output shaft of the trans after spinning when you put the truck in gear. Next time, leave the trans in neutral for a bit before shifting to park.

    When you say "auto 4wd" do you mean push button selection?

    Probably have 2hi, 4hi, 4lo? It's possible that you have a wiring problem, blown fuse, or the switch is faulty. Also possible the encoding motor crapped out mid shift. You can get under the truck and remove the shift motor. There is a shaft extending out from the case, with flats on two side. Use a wrench to turn the shaft. I think it's 14mm. Don't use pliers/vise grips, they will damage the shaft. I don't know which rotation direction is which, but there are four positions. 4lo, N, 4hi, 2hi. Turn it all the way in one direction and see if you get back into gear. It doesn't turn far, about a quarter turn total if I recall.

    What doesn't make sense is that neutral is basically halfway between hi and lo range. I'm guessing you didn't try to put it in lo range while driving, and it shouldn't allow it to change ranges above a few MPH anyway. \

    Be sure to set the park brake and chock the wheels before climbing under the truck.

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