By on May 27, 2015

module. Shutterstock user BLKstudio

Gary writes:

Good Afternoon,

Today when I got into my 2002 Saturn SL2, the power door locks started chattering. Each door, over the space of about 45 minutes, had the same thing happen. Sometimes it would be one at a time, other times it would be two or more. I also noticed that the inside locks – the “up/down” button, not the little lever you use to manually unlock the car – would not work, only later to work. For now I have removed the lock fuse and that stopped the problem. I wait and plug the fuse back in, and the sporadic chattering once again begins. Sometimes it is completely quiet. Any thoughts?

Thank you!

Sajeev answers:

Whenever a problem like this occurs, I blame something Body Control Module like. When guidance systems break down? When there’s a struggle to exist? To resist?  That’s not a mere switch panel or short in chassis wiring. Oh no, Son, this is some heavy duty FAIL right here.

A body control module that’s scared out of its wits is the only culprit behind such berserk behavior. My apologies to the TTAC mothership (and all Torontonians) for such a shameful riding of RUSH’s coattails.

If I’m right, the video (below) is helpful. Ditto this Saturn forum link, complete with the body control module’s pinouts for your testing pleasure. A replacement is over $200 at Rockauto, rebuilders on eBay want over $150 for the privilege. So you’d be wise to test the wiring, get a factory shop manual and perhaps learn the proper BCM diagnosis method.

And don’t forget the BCM recall, too!


Send your queries to [email protected]com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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24 Comments on “Piston Slap: The Body Control Module Electric?...”

  • avatar

    p/g FTW!

  • avatar
    SCE to AUX

    Yep. The same thing happened on my former 98 Grand Caravan.

    The BCM is pricey, and so is having an auto electric shop install and program it for your particular vehicle.

  • avatar

    The infamous early to mid 2000s gm body control module. Saw a lady have to get towed on the back of a flatbed while stuck in park because the bcm went bad in her saturn and wouldn’t let her start the car, shift out of park, or remove the key.

  • avatar

    Spilled any energy drinks into the carpet lately?? Seriously, by default, I start troubleshooting flaky electrical problems by checking the grounds.

    • 0 avatar

      If these BCMs are known to have problems, it could be. But I see door switches(modules) get soaked by an open window at one time, maybe months/years ago, turn into a green monster and no longer function reliably. Better to disconnect door connectors, even have a Tech2 handy and see if things change.

  • avatar

    While some speculate that you are facing a mere GM parts bin issue, I would like to suggest that this may be a message from God. Your Saturn may be possessed, and it’s time to upgrade. Put a burned-out fuse in the appropriate slot, sell Saturn on Craigslist stat, and put the hundreds in proceeds toward another car. Doesn’t much matter what you choose – pretty much anything is bound to be great in comparison, unless you find a great deal on a VW of similar vintage. If so tempted, please instead get a bicycle as the car gods obviously have it in for you.

  • avatar

    Sajeev, the recall only involved the Opel derived L-series Saturns, not the S-series.


    Only selected 2000 – 2002 mode/year L-Series Saturn vehicles within the following VIN ranges will require this campaign:”

    • 0 avatar


      Who would have thought that, in 2002, a Vectra based Saturn with an English engine would have been a bad idea? This is the worst sort of GM thinking.

      • 0 avatar

        Vauxhall assembled them but technically zee Germans designed it.

        “General Motors’ Opel subsidiary in Europe designed a compact V6 engine with an odd 54° vee angle. It was an iron block/aluminum head DOHC design with 4 valves per cylinder. All 54° engines were assembled at Ellesmere Port in England.”

        • 0 avatar

          Right. Nevermind that GM already had perfectly suitable V6 engines in the US. I would take the 3100/3400 over the 3.0L.

          (I am assuming that GM would not have put the 3800 in the L-series)

          • 0 avatar

            “I am assuming that GM would not have put the 3800 in the L-series”

            Well this would have made entirely too much sense, so no. Shipping a US built motor/drivetrain to Europe and then fitting/testing/certifying it to an Opel would have been too expensive. What happened here I suspect was simply an excuse to exploit under utilized Opel/Vauxhall capacity. Just like L-Series, Aura, Astra, Catera gen 1, Regal etc. Whats funny is many years ago when I first learned L-Series and Catera were Opels I thought “pretty cool”, but now I’ve learned Opels suck just as much as most other German cars.

          • 0 avatar
            heavy handle

            28, wiki says the L Series were built in Delaware, not in Europe.

            The reason why GM used the 54° V6 instead of the 90° 3800 is that the 90° engine did not fit the platform.

            The L-Series was a half-assed effort to compete in the mid-sized segment, so they grabbed whatever international platform they could find (a 5 year old Opel), added cheap interiors, and called it a day.

          • 0 avatar

            Thanks for the info, I let too much Catera history cloud my thinking.

    • 0 avatar

      Oops, thanks for that. Too many Saturn forum tabs were up while researching the problem.

  • avatar

    I know exactly what the issue is.

    You’ve got a bad power lock switch.

    My exGf’s 98 SL1 used to do that all the time, and it was inevitably the drivers side power lock switch would fail, and causes the locks to chatter.

    It probably also feels different compared to the passenger side. What’s happened is the centering pin/spring for the switch has broken and allowing the switch contacts to bounce, instead of opening the contacts up like it normally does.

    the BCM in this case isn’t an issue, it’s a $5 junkyard switch. two seconds with a flat tip screwdriver to pry it out of the junk car, and you’re good to go.

  • avatar

    I had the BCM go out in my Dakota, it lead to all kinds of weird issues with lights. Headlights would randomly blink, the dash lights would fail, turn signals would randomly turn on and off and other crazy things. I thought the truck was possessed!

  • avatar
    schmitt trigger

    Not related to the Saturn, but to the Body Electric video.

    Remember seeing it for the first time at a hotel in El Paso. Awesome. Light years ahead from the usual MTV fare.

  • avatar

    Oh yes, that will do it. I’ve seen body control modules fail on lots of General Motors vehicles, mainly Pontiac G6s for some reason. One indication from outside the car is when the brake lights stay on while driving, but turn off when the brake pedal is depressed.

  • avatar
    Felix Hoenikker

    Anybody know why are these modules keyed to the car’s VIN?

    • 0 avatar

      The same module can be configured a variety of different ways for vehicles with different features. Keying it to the VIN allows to be configured properly for that specific vehicle’s options.

    • 0 avatar
      SCE to AUX

      Some of them also control the odometer, whose reading needs to be implanted into the new BCM. As you know, the odometer reading is an Important Thing.

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