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How-to: Remove and replace ECM

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    How-to: Remove and replace ECM

    I took my car to my mechanic today to have him look at why the cooling fan isn't coming on (AGAIN). He informed me he'd previously wired it to ground through the ECM, and that I probably have a malfunctioning computer. This was backed up by the fact that last time I took it to him he tried to run his diagnostic tool on it and it said it couldn't communicate with the car. He then wired it directly to the ignition so it would come on with the key regardless.

    What the hell, I thought, may as well get a "new" computer. Headed off to the junkyard, looking for an 87-89 2.8/4 speed A-body. Wasn't having much luck until I came across a beige Celebrity. And damned if it wasn't an '89! It took me all of five minutes to get the thing out, since someone else was kind enough to do half the work for me.

    Anyway, I dropped some new batteries in the camera and documented the process.

    Here is the computer I acquired. As I said, it came from a 1989 Celebrity, 2.8/4 speed, full cluster, pretty much all the options my car has. Note the sticker, which reads "REMANUFACTURED BY GENERAL MOTORS CORP."

    First step is to, of course, disconnect the battery. Too bad GM didn't have any foresight and made it almost mandatory to move the strut brace.

    I don't have an 8 mm wrench for some reason, and a ratchet + socket is too big to fit... it's easier to just pull the battery out completely.

    The ECM on this car is actually pretty easy to get to.

    Nobody's home.

    One side, one side.

    You can't hide from me.


    Three harnesses are attached.

    Check out the sticker. It's old as hell. It fell off when I touched it.

    So lonely.

    And if you've never heard this one before: "Installation is the reverse of removal."

    No check engine light, ran just fine. We'll see if it's solved my cooling problem. If not, oh well, only spent $33 on it. And to stave off the inevitable question, I did not swap the PROMs. I don't trust my clumsy-ass fingers handling something so delicate. I might end up getting a custom chip though, haven't decided yet.
    Kaiser George IX: 1996 Buick Century Special wagon. 214-SFI. 227k miles. Never gonna give you up, never gonna let you down. First documented LX9 swap in an A-body! Click here to read my build thread!
    Goldilocks: 1992 Buick Century Special sedan. 204-MFI. 132k miles.
    Susana: 1993 Buick Century Custom wagon. 204-MFI. 121k miles. No longer with us.