Hazard light flashes when car is locked

TDCHRYSLER

MEMBER
2014 BUICK LA CROSSE
AUTOMATIC
106,967 MILES

Hello, so my Buick La Crosse now flashes the hazard lights when it locks, and the alarm engages. Meaning that when the car is turned off, it automatically locks, and sets the alarm, in about 5 minutes or less the hazard lights begin to flash on their own. Even when I press the unlock button on the key fob the lights will continue to flash until I press the hazard light button in the car, then it turns off. I tried taking the terminal off and back on but that did not do anything. I also would leave it and see if it may turn off on its own, but no change. Also, sometimes when it does this the trunk will open on its own or the alarm will just go off. So now I'll have to take the negative terminal off and put it back on whenever I would have to move the car. Does this issue sound like anything familiar?

7 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,602 POSTS

Yep, it sounds like the BCM is going out. To be sure let's do a CAN scan which is the future of automotive repair you can get a CAN scanner from Amazon for about $30.00. here is a video to show you how and a link to a scanner from Amazon. I have left instructions on how to change out the BCM in the diagrams below.

https://youtu.be/u-4syLc-ifQ

and

https://amzn.to/3OpAotj for the scanner

Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.

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Wednesday, June 29th, 2022 AT 12:08 PM

TDCHRYSLER

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Okay, thank you for this information. After having the car scanned the code:
U0140 - Lost communications with BCM.
I attached the image below so that you can see what displayed. Also, is there a way I can get the model/part number for my BCM without having to remove it first?

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Wednesday, June 29th, 2022 AT 6:24 PM

KEN L

MASTER CERTIFIED MECHANIC
47,602 POSTS

Nice work on the scan.

Body Control Module - 13580698 - $198.37 OEM

Please let me know what happens.

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Thursday, June 30th, 2022 AT 8:24 PM

TDCHRYSLER

MEMBER
19 POSTS

Thank you for the help.

Will let you know what happens.

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Friday, July 1st, 2022 AT 6:43 AM

TDCHRYSLER

MEMBER
19 POSTS

So, update so far, I took the LaCrosse to my Auto Technician for the BCM issue. He then informed me what is causing the BCM to malfunction is my passenger side headlight. That headlight is no good and was wired poorly interfering with the power from BCM. After scanning the car and the checking the BCM, all the codes were coming clear except for the power interference of the bad headlight wiring/receptor (if I am remembering exactly.) So, I will purchase the new headlight and let you know what happens moving forward.