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Thread: 4l80e swap issues

  1. #1
    Join Date
    May 2008
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    4l80e swap issues

    Recently completed a swap in the white truck. I'll give you the complete history of Trans to my knowledge to perhaps help ideas.
    The 80e is a 06 model. 70k miles. Pulled from a truck that got clipped on the side. Friends and I installed a transgo hd-2 shift kit. ( I throw that in to make clear if you think this could be part of the problem by all means say so you won't hurt my feelings. ) install went easy. Using stock converter. I've double checked the wiring to the PCM. I have not yet doubled checked my work on the sensor that plugs into valve body.
    I've tried two tunes from different years so far. The segment swap isn't as easy as it should be. Some dildo through the trucks history loaded a custom VCM OS ID. I don't know if this was done by the first tuner TR or perhaps from gm. Word is the first owner was a paralyzed individual and it had everything a up for him to control it through the steering wheel. That was all removed when he sold it.
    NOW what it's doing is. The gears are shifting as soon as the truck starts moving. I put it in drive it will jump to 2nd by 10 mph. 3 right after and be in high before I get to 15 mph. Also doesn't want to down shift until at a complete stop. Strangely and by complete accident to keep it from going dead I found it would shift into reverse while moving ( I had hell getting the park-neutral safety switch off the 60e and installed on here so that's a possibility ) it is throwing me two Trans codes.
    P0740
    P0785
    Both coming back to solenoids. Any help greatly appreciated. I do currently have hptuners a copy of tune to see if the segment swap is working correctly. Current segment swap is from exact year model as mine.

  2. #2
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    No ideas ?

  3. #3
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    are you getting a vss signal?

  4. #4
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    Quote Originally Posted by farmtruc View Post
    are you getting a vss signal?
    That's exactly what I was thinking. Sounds like the pcm doesn't know what the rpms or speed is or its programmed shift points are waaaay off... but what gets me is that it DOES down shift. Super late, but still. Which means it's getting a reading from somewhere right?

  5. #5
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    Mar 2003
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    it could be an erratic signal, all over the place, forcing it to up and downshift.

    scan it and make sure it's a nice clean signal/reading.

    then export it to an xls sheet, (keep eyes on road ) and look down the column for spikes.
    just a thought, and one less variable excluded.

  6. #6
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    anytime i seen a 4l80 not see VSS it had park, 2nd or reverse. as thats the Default settings in case you lose pcm power to trans
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  7. #7
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    Well hptuners were able to segment swap a correct segment on it. Apparently it had a custom VCM os id loaded on it sometime during its life. And nothing I tried was right. The correct segment installed shifts like a charm.

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