Something is draining the battery?

NINETYN9NE

MEMBER
2006 CHEVROLET TRAILBLAZER
4.2L
V6
4WD
AUTOMATIC
90,000 MILES

We brought a new battery and when it will start the very next day the car wouldn't start. You can jump it or at times the battery can be unhooked from the cables and upon re-attaching them the car will again start. Otherwise, the car doesn't run due to the constant draining. The car was looked over by a technician and he couldn't find the cause of the drain. The engine does not have 100,000 miles and is seldom driven.

Thursday, January 19th, 2023 AT 9:06 PM

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
51,685 POSTS

It sounds like the BCM is not shutting down which common when it goes bad, but I need to ask was there a CAN scan done? You can get a CAN scanner (Controller Area Network) from Amazon.

Here is a video to show you how:

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

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Also, with that big of a drain there with be heat, with the engine cold place your hand on the alternator when the battery is fully charged to see if it is warm, if so, you have found the problem because the alternator has an internal short.

Here is a guide to help you to see what's going on:

https://www.2carpros.com/articles/car-battery-dead-overnight

Here is how to replace the alternator in case you need it. I have also seen the instrument cluster short out and cause this issue as well. Check out the images (below). Please let us know what you find. We are interested to see what it is.

Images (Click to make bigger)