Radio and lights on the dash stay on after turning the car off?

KEYZEEY1995

MEMBER
2004 CHEVROLET MONTE CARLO
3.8L
6 CYL
2WD
AUTOMATIC
215,000 MILES

I blew my head gasket about 6 months ago. I finally got a new engine put in. Car ran good but I noticed that when I turned the car off the radio would still be on as well as the lights on the dash. I thought the lock cylinder or switch was the problem so I had both of them changed as well and the problem persists. I don’t have an aftermarket radio. Please help, it's constantly draining my battery.

Thursday, March 23rd, 2023 AT 9:34 AM

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
54,137 POSTS

Did the electrical problem happen at the same time as the engine installation? If so, I would recheck the system grounds. Also, we should check all fuses with the key on because if there is a fuse out the BCM may not turn the systems off, this guide can help with the fuse location in the images below:

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

If the fuses are okay, we should do a CAN scan because it sounds like the BCM is out. 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

I included the BCM replacement instructions as well, you can get a preprogrammed BCM by searching Google or Ebay. Check out the images (below). Please let us know what happens.

Images (Click to make bigger)