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Thread: ALDL connector pins - how loose is too loose?

  1. #1
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    ALDL connector pins - how loose is too loose?

    I need to get to the bottom of an intermittent communications problem on a '95 Caprice LT1. I've been getting intermittent dropouts during data collections and then after things seemed to clear up, I had a failure on a PCM load (doorstop!). The ALDL plug is extremely loose in the car's port. Looking at the plug and the port, the male plug pins are nice and tight inside the molded. On the '95 LT1 port there are only three pins present, and they have a ton of front-to-back play. There appears to be a white plastic insert that fits in behind them, but it is just flapping around in there. I looked at some other ports from similar Caprices in the junkyard and they are all just as loose!

    I'm sure the actual individual female connectors are relaxed as well and could probably use to be retensioned with a pick or something?

    I'm thinking a couple of things:
    1. The ALDL plug has more male pins than the car's port has female connectors. I could add a few extra dummy connectors to strengthen the physical retaining ability.
    2. One the connectors are retensioned, pack the back of the port with hot glue to lock the pins in place to keep the connectors from shifting around.

    Part of me would be okay with a benchtop programming setup for safety's sake (have you done this?) but I've never had a problem with my other '94 LT1 car and this car has toasted two PCMs now, so it seems that there's a problem specifically with this one. It also doesn't solve the datalog problem.

    What's your experience with this?

  2. #2
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    i've plugged and unplugged an ALDL cable in couple of cars MANY, MANY times and i have yet to experience loose pins/intermittent connections. perhaps the ports used on the 94-95 LT1/L99 cars were made slightly differently? is this still the 12 pin or 16 pin connector?

    but if i were experiencing loose pins... i'd probably go route #1 and 2... or just 3(hardwiring in the ALDL circuit).

    those two "junked" PCMs could just have their PROMs desoldered, sent to somebody with a Willems programmer with the BIN files seperated, reburned, then resoldered(maybe in a socket in case it happens again in the future) and they'll be useful again.
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


  3. #3
    EFI GearHead ! EagleMark's Avatar
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    They all move around a little in the ALDL port which is not an issue. The inside is spring loaded for a good connection on the ALDL plug.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
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  4. #4
    Fuel Injected!
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    This is the older square style. All of the newer cars I've plugged into for scanning/monitoring seem to have a much more physically tight positive connection between the port and the connector body.

    One other option I thought of is reangling the mount of the port so that it faces upward instead of downward. This way, gravity would help keep the connector in the port rather than the other way around.

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