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No 4wd

Discussion in 'Chevy Trucks' started by B&E snowplowing, Nov 12, 2007.

  1. B&E snowplowing

    B&E snowplowing Senior Member
    Messages: 159

    My 1990 GMC 2500 seems to be sick.

    When I shift the shifter from 2wd to 4wd (hi or low) the 4wd does not engage, it sound like the transfer case is engaged but I have no power at the front axle. Any ideas where I can start to look...4wd worked great last winter, the truck sat most of the summer,so I can't understand what has happened.

    All the fluid are full, so now i'm stumped
  2. grandview

    grandview PlowSite Fanatic
    Messages: 14,609

    Hubs locked?
  3. jryden145

    jryden145 Member
    Messages: 86

    It is probably the actuator, the same thing happend on our 93 chevy and we replaced it and it worked fine. Its also nice becasue the new updated actuators make it go into 4wd faster

  4. B&E snowplowing

    B&E snowplowing Senior Member
    Messages: 159

    Is this actuator expensive, and is it hard to change....Do I have to mortgage my house to get it fixed, or can I do it myself, since I am mechanically inclined.
  5. PlowMan03

    PlowMan03 Senior Member
    from Maine
    Messages: 471

    I have to agree with jryden145. Also you might want to check the actuator hoses to see if they are weather cracked from sitting all summer.
  6. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

  7. gcsupraman

    gcsupraman Senior Member
    Messages: 110

    Exactly what I was going to say. If I remember correctly, it screws in near the front axle area on the passenger side and its about 1 inch in diameter - I think it was silver. It has a hose running out of it. I remember changing one about 5 years ago and the updated one is electronic and not electrical so there is 1 power wire to run.

    The old ones are problematic over time and the new one is not that expensive. $100?

    Here is a pic of the new one:

    Last edited: Nov 12, 2007
  8. gcsupraman

    gcsupraman Senior Member
    Messages: 110

    Here is a pic of a chevy ifs system with a posi lock installed....you can see the new posi lock actuator in the old housing. Look there under your truck for it....

  9. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    It's easy to change and a common problem. My Brother inlaws went bad in his 93 GMC. It took about 1/2 hr to change once the truck stopped dripping ICE WATER. PB Blaster -ed it for a while before I took the old one out.
  10. B&E snowplowing

    B&E snowplowing Senior Member
    Messages: 159

    No 4 WD

    I changed the actuator yesterday took about 1/2 hr. and everything is back to normal.

    Thank for the input, saved my some cash for the diagnosis