Battery drain?

Tiny
ART SIGMAN
  • MEMBER
  • 2008 CADILLAC SRX
  • 4.6L
  • V6
  • 2WD
  • AUTOMATIC
  • 135,000 MILES
We've had three new batteries in less than two years. The latest new battery was just installed a couple weeks ago and it's already not wanting to start without a jump. We heard a little clicking noise yesterday while trying to jump start it, any suggestions please?
Wednesday, August 31st, 2022 AT 6:58 AM

3 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,782 POSTS
The little clicks are normal when the battery is low, but I think what is happening is the car is no going into "sleep mode" because of a bad BCM which is common but to be sure let's do a CAN scan which is easy to do. You can get a CAN scanner from Amazon for about $30.00.

Here is a video to show you how:

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

Here is how to replace the BCM in case you need it in the images below. You can find a rebuilt BCM if you search Google, have your VIN number ready for reprogramming. The export (euro) is one the left side btw. Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.
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Wednesday, August 31st, 2022 AT 11:11 AM
Tiny
ART SIGMAN
  • MEMBER
  • 1 POST
Our mechanic checked the sleep mode, and the vehicle is doing what it was supposed to. Also, my wife had just driven the vehicle for an hour or so and shut it off for about 10 minutes then went to start it again and vehicle wouldn't start again? Thanks
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Monday, September 19th, 2022 AT 7:11 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,782 POSTS
Okay, then we need to check to see if the alternator has a diode out which will cause the alternator to charge with AC voltage which ruins batteries fairly quickly. Use a voltmeter and switch it to AC voltage with the engine running to see.

Here is a guide to help:

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Please go over this guide and report back.
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Monday, September 19th, 2022 AT 7:15 PM

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