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4L80E Trans problom

Discussion in 'GM Powertrain' started by rlander06, Mar 13, 2010.

  1. rlander06

    rlander06 New Member

    I have a 1995 Chevy 2500 pickup with a 5.7 and a 4L80E trans . My problems is I put the shifter into OD and it will shift up to 3rd gear untill I reach 30MPH after 30 it will kick down to first untill I slow back to 30 then it will shift up to 3rd gear. Then I put the shifter in 3 and I can get up to 40mph before it kicks out of 3rd untill I slow down. And then some times it will not shift out of first gear at all after it has sat awhile.I hope you understand what I am saying. If you need more info I will try to make more sense.Thanks for your help
    P.S The shop I took it to said my ECM was bad and some bad wires, so they put a new one in and I still have the same problem.
  2. xmrracer

    xmrracer New Member

    are you running an aftermarket ignition at all like a MSD ?
  3. rlander06

    rlander06 New Member

    The ignition is the same that came with the truck when I bought it about6 mouths ago.The truck ran fine for 4-5 mouths and then started to act up.
    P.S. I don`t know if this has anything to do with the tranny but, I can pull the keys out of the ignition any time with the truck running and in gear.
    Last edited: Mar 14, 2010
  4. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    You may have a bad ignition switch or you could have a bad shift solenoid. Check the voltage at the transmission fuse while cranking the engine. If the voltage drops below 9 volts you probably have a bad ignition switch. Do your dash lights dim while cranking? Does your tach act up?
    If the ignition switch is OK then you need to check the solenoids. First step is to get the trouble codes. And believe me you have trouble codes stored in your computer.
  5. rlander06

    rlander06 New Member

    My truck is back up and running. I took it to anouther shop. They found that the harness to the computer was bad ( burnt wires and pins). Also the wire harness in the tranny was burnt. They also replaced the ignition switch ( the electrical part ) The first shop said I needed a new computer and went and put one in but it did not fix the problem. The problem was all in the pins and wire harness and switch. So now I have a new computer for no reason.

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