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Thread: Bad 1st time experience. Need a a Source for a 3.1 V6 Bench Harness

  1. #1
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    Bad 1st time experience. Need a a Source for a 3.1 V6 Bench Harness

    Hi All,

    First time hptune user. 2000 Chevy Malibu. It did not go well although I think I dodged a bullet.

    I disconnected aftermarket radio before starting. Completed a read, saved file. Made some mods, saved new tune and tried to write. Said "erasing" for a bit, chimes dinged, then the dreaded "controller unlocked timed out". Car would cranks but would not fire up or start. I tried recycling the interface to no avail. I was really worried that I had brciked the car. I then disconnected battery and she started back up.

    In retrospect I suspect the aftermarket remote starter is interfering. I do not want to chance bricking the vehicle by trying to update again and getting partway through a write process. Thus, seems like a bench harness might be the safer approach.

    I see lots of V8 bench harnesses on ebay and Amazon. Is there somewhere I can purchase same for the 3.1L? If someone were willing to make one up and sell it to me, please PM.

    Here is a V8 example. Not sure if they are compatible?

    https://www.ebay.com/itm/15384470383...m=153844703831

    Alternatively, plans or diagram for making one and sources for parts (I am guessing it needs a power supply of some sort as well).

    I do not want to rip out the remote start system. If that does tap into an OBDC port or wire would it be as simple as disconnecting that or, does the evil of these remote start systems run much deeper.

    Thanks in advance. I've done lots of mechanical work but this is a new realm for me.
    Last edited by Amphicar; 11-30-2020 at 10:17 PM.

  2. #2
    How long did you wait before hitting write after key on? Try it again after disabling the remote starter although I don't see that being a factor here.

  3. #3
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    Quote Originally Posted by Jeff7577 View Post
    How long did you wait before hitting write after key on? Try it again after disabling the remote starter although I don't see that being a factor here.
    Thanks for the reply.

    Ignition remained on from time I initiated read through time I attempted to do the write. Not sure how long between, maybe 10 minutes by the time I saved the tune file and went to write it to vehicle.

    I did just discover that there is a physical toggle switch to disable the remote start system. At lease there is supposed to be one. I will have to check with the shop who installed it to see where they might have hidden it. May make another attempt after that.

    I would still like to find a bench harness, seems like that would eliminate a lot of variables. While the LS1 harness looks identical, I am guessing it may be pinned differently that the 3.1 V6?

    Thanks again.

  4. #4
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    So, I tried again after disabling aftermarket remote start. I successfully was able to write twice but it took a few attempts of disconnect / reconnect battery, restart process. I have noticed that if "erasing" takes more than a few seconds i wind up with the timeout issue and have to go through entire cycle with battery disconnect, etc. My third write attempt has been unsuccessful after multiple cycles.

    Definitely something wierd going on that seems to be common with GM vehicles. Just glad it did not brick the PCM.