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'01 1500 No 4x4

Discussion in 'Ram Trucks' started by NPMinc, Mar 15, 2011.

  1. This weekend while using this truck to remove fallen branches from my yard, I noticed that the 4x4 was only engaging sporadically and now today it wont engage at all. No 4x4 dashlight, no hub engagement etc. I briefly got under it and verified that the shift lever was working the transfer case lever and didnt appear that vaccuum lines off the transfer case were rusted through broken etc. Any ideas/help is apprecited as my mechanic is in the Bahamas on his honeymoon and I dont really wanna rush it to a trans shop as this is simply a yard truck, backup truck etc. Thanks!
  2. MrPLow2011

    MrPLow2011 Senior Member
    from Boston
    Messages: 276

    Did you check to see if the vacuum line came off the top off axle up near the hubs? i am pretty sure its on the passenger side by the tire
  3. MrPLow2011

    MrPLow2011 Senior Member
    from Boston
    Messages: 276

    Check 2 vacume lines under body by cross member bar and plug in if out controls vacume to front hubs
  4. justme-

    justme- 2000 Club Member
    Messages: 2,138

    odds are they are attached since the OP said it was sporadically there. Once the lines come off they don't put themselves back on....

    Check the lines- more for damage then anything. Then follow them back to the transfer case- there is a ball switch the lines attach to on the top of the case- unplug the lines and remove the switch. You want to check the ball (visible when the switch is out) is freely movable. They will bind on occasion and cause the vacuum not to proceed to the axle. A swift tap to the ball should free it if stuck. Reinstall and reconnect the lives (single plug on the switch).
    If 4x4 is still not working, odds are it's the vacuum solinoid on the front axle - they go bad either seizing or the diaphragm leaks. Pull the CAD cover plate (4 bolts holding it to the axle) and try to move the shift fork. If it moves (not seized) put a vacuum source on the ports and see if it tries to pull.

    New solenoids are about $160 online.

    FWIW, vacuum lines were a combination of hard plastic and rubber - both fail in time so you might want to look at the lines for cracks/leaks all over the truck. Low vacuum from a leak somewhere else will result in the same situation you have because there is not enough vacuum in the system to hold the axle engaged.
  5. USMCMP5811

    USMCMP5811 Senior Member
    Messages: 267

    That's where you want to start. Turn on your defroster and then switch to the floor setting, and then vents. Does your heat stay on defrost at all times? If it switches to the other options, does it go to defrost under hard acceleration? If so, then you have a vacuum leak. check all your T fittings at the back of the intake manifold by the throttle body. Most common cause is vacuum or should I say, the lack there of....

  6. Thanks for all the suggestions guys. I am pulling it into the shop tonite and will keep ya posted. Thanks Again!!!