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Trans/4X4/ABS problems

Discussion in 'GM Powertrain' started by jnbascom, Nov 30, 2009.

  1. jnbascom

    jnbascom New Member

    Hi all. I am new to this site and hoping to get some ideas on how to get this truck fixed. It is a 1999 GMC Jimmy 4X4 with 150K miles and the 4 button 4X4 selector switch.

    First problem-transmission: When driving very long on the freeway (more than 10 miles) truck shifts out of overdrive and will not go back in. Also, when this problem occurs, when you let off the gas the torque converter completely disengages. It shiftas really hard from 1st to 2nd intermittenly. It will run perfect for a while then starts shifting hard. Temperature doesn't seen to make a difference.

    Second problem-4X4: Cannot get the front diffefential to engage. It will shift into 4 hi and 4 low but the front differential will not lock in.

    Third problem-ABS: There is a clicking sound coming from the kick panel on the passenger side. Sounds just like the hazards are on but I beleive it has to do with the ABS because when you step on the brake pedal, even a little bit, the noise stops.

    Please help as this thing is driving me crazy!!!
  2. Jimmiee

    Jimmiee New Member 1000 Posts 100 Posts

    You first step is to get the truck scanned for trouble codes. This will save lots of time and money throwing parts at the transmission problem. The 4X4 problem is probably a front actuator as this is common on your truck. As for the ABS the clicking may be some debris between the sensor and rotor. Get your truck scanned and report the codes.
  3. jnbascom

    jnbascom New Member

    Thanks Jimmy. The clicking noise sounds like the blinker is on but it is not. It is coming from the passenger kick panel and stops when the brake pedal is depressed that is why I was thinking it had to do with the ABS. I have alson read a lot of threads on the ignition switch being a POS on these trucks. Would that have something to do with the gas gauge not working correctly and possibly the clicking noise?

    One more thing, the code the computer is throwing is "P1870" which is trans slippage. There is a repair kit for the valve body from Sonnax for less than $200 including the reamer. This will fix the slippage in these higher milage vehicles. It is common in 99% of the 4L60E transmissions.
    Last edited: Dec 1, 2009
  4. Jimmiee

    Jimmiee New Member 1000 Posts 100 Posts

    Yep, the 1870 code is usually a worn TCC regulator valve in the valve body. Instead of buying the reamer tool which you will never use again a better choce would be to buy a reman valve body that has all the updates. VBX has a good product. Click Here
  5. Jimmiee

    Jimmiee New Member 1000 Posts 100 Posts

    Here's a link to TransGo's video library. You can download a zipped file which gives a step by step view on how to R&R the valve body and install their kits. Good video demos here.

    Click Here
  6. jnbascom

    jnbascom New Member

    Thanks again. Do you have any idea what the clicking noise is coming from the passenger side under the dash? Like I said in my earlier message it sound like the hazards or blinker is on but it is not. Could it just be the key switch or am I looking for something more?
  7. Jimmiee

    Jimmiee New Member 1000 Posts 100 Posts

    It could be a relay. Can you have someone else drive the truck while you get down there and listen to the noise? That's the best way to pinpoint it.
  8. jnbascom

    jnbascom New Member

    That should be pretty easy as it does it when its not moving and while driving. It is intermitten but for the most part it will just stay on even when the ignition is in the run position but not started. I will tear apart the kick panel tonite and let you know what I find. Thanks for all your help.

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