Door/trunk ajar and dome lights stay on drain battery while car is off or on

KINGTB012800

MEMBER
2004 BUICK CENTURY
3.1L
6 CYL
2WD
AUTOMATIC
100,225 MILES

Hi, my name is Tb.

I wanted to put a double din in my car so I did everything I had to do, but I felt too good to unplug the battery (more of story). I plugged the wire harness from deck to factory harness went to slide the double din in cubby the black wire from the deck came unhooked from the wire harness I plugged black from deck back to the black on the wire harness doom. Car shuts off. So, I put the factory radio back in because the car wasn't turning back, so I though I ruined the battery. Went to charge battery was drained but still good. Go home, plug it back into the car and drive around everything is good. Next morning I get in the car and door/trunk ajar pops on, dome light and the light under dash stays on. I checked all fuses, replace the alternator. I just need help. I'm located in Tacoma, WA. Any ideas what to do?

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

If the trunk ajar light stays on, then that is going to cause the dome light to come on.

So, we need to figure out why the trunk is remaining "open"

This circuit is just a simple open closed switch. So that means when the trunk is open and closed it opens and closes the switch. This completed circuit or open circuit tells the BCM if the trunk is open or closed.

So, we need to check the voltage on this circuit and see if there is voltage there when the trunk opens and closes. Here is a guide that will help with this:

https://www.2carpros.com/articles/how-to-check-wiring

Below you will find the wiring diagram that will help with this. However, if the voltage goes away when the trunk is open then the switch is fine, and the issue is in the BCM.

Let me know what questions you have with this.

Thanks

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