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4WD not engaging-86 S15 Need help!

Discussion in '1983-2005 S-Series models' started by mkmiller, Aug 31, 2003.

  1. mkmiller

    mkmiller 1/2 ton status

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    got an '86 s15:2.8L and auto. When you shift into 4wd the light comes on but the front hubs don't engage. When in 4L you can feel the lower gearing but the front wheels still won't pull. WHAT'S UP???
    I've had a '93 Z71 and had to replace the actuator on it but this one looks different. I pulled the little thing that the wires plug into and it just has a little ball-bearing looking thing in the end, I'm assuming this just makes the lights in the cab work. What should I replace?
    thanks,
    Matthew
     
  2. HarryH3

    HarryH3 1 ton status Author

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    If it's setup like my '91, there's a vacuum switch on the very top of the transfer case that sends engine vacuum to the front axle engagement servo when you shift into 4WD. I bought a new one from the GM dealer for $18 and my front axle worked fine once again. /forums/images/graemlins/thumb.gif
     
  3. rigdonhome

    rigdonhome 1/2 ton status

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    [ QUOTE ]
    If it's setup like my '91, there's a vacuum switch on the very top of the transfer case that sends engine vacuum to the front axle engagement servo when you shift into 4WD. I bought a new one from the GM dealer for $18 and my front axle worked fine once again. /forums/images/graemlins/thumb.gif

    [/ QUOTE ]

    Agreed... I think there are 3 vacuum lines coming out of it and it is a common problem.

    You should also check the actuator that is similar to your Z71. On the early S10's it was vacuum activated by the above mentioned switch. If the pod doesn't hold vacuum it won't be able to pull the cable that engages the front hubs. On the early S10's the pod was mounted on the passenger side fender well, and around the late '80's they relocated it because it was far too easy to reach. They put it under the battery tray so you have to remove both the battery and tray to get to it.

    I'm pretty sure I have an extra vacuum pod if you need one cheap. I seem to remember they were kinda expensive from the dealer. They are probably pretty common in your local yards too. PM or email me if you need one.

    Sal
     
  4. mkmiller

    mkmiller 1/2 ton status

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    thanks for the help. It turnoed out to be a cracked vacuum line right at the pod. New line and now it works!
    /forums/images/graemlins/thumb.gif
    Matthew
     

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