trunk opens itself when raining... something shorting out? [Archive] - Forum


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06-24-2012, 04:17 PM
this has been going on as long as i've owned the car. when it's really moist weather, sometimes i notice the the trunk will be cracked just like i've pressed the remote button. the car isn't under a garage anymore, so now it's a problem i hafta fix.

right now my trunk looks like this...

also, on humid mornings, the ABS light and the TRAC OFF lights come on about thirty seconds after i start driving. there is usually a jerk or slight stalling of the engine just before this happens. the next time the car starts up it will be okay.

is the BCM likely to short out with morning dew? do i have gremlins in my car?

i can turn off the motor on the trunk release and go back to using the key to actually open it, but i wonder if the trunk button in the door is getting wet and shorting out...

06-24-2012, 08:35 PM
Wow, that's a weird problem.

Well for the trunk button in the door, it should be kept dry by the vapor barrier behind the door panel. The wiring does go through the vapor barrier into the door, and through the rubber flex tube between the door and the body. I suppose if the wire insulation was cut somewhere in there it would be possible to short them out and activate the release. It's not a very common problem though with how well they usually wrap the harness. It could also be the same problem with the harness in the trunk, but also not likely. It could possibly be moisture getting to the BCM, since the remote for the keyless entry will also release the trunk, so there is a circuit for that in the BCM. I'll see if I can dig up the wiring diagram in my manual tomorrow.

Have you ever noticed any water or dampness on the passenger side carpet, or under the carpet on the floor of the car? I'd pull back the carpet and check, and take the kick panel down from under the dash and look for water spots or rust under there. Any sign you could have a leak letting water in when it rains.

06-25-2012, 12:29 PM
My trunk did that about 3 or four times after it sat before it got fixed. I found water in spare well a lot. After a while it didn't do it.

06-25-2012, 04:40 PM
Why are you complaing about the trunk if it has a hot wet chick in it? Hehe
Mine did that last winter as i was driving and blasting my 1200watt subs. My problem wasnt the wireing but the trunk latch, quickest n cheapest way to try to fix it (assuming that its not electrical problem) is to spray the trunk latch with some WD40 or such products, then play around with it for a bit.

06-26-2012, 05:53 PM
My trunk was doing that same thing recently but it was because my battery was dead. When I tried to start the car with such a low battery the trunk would pop open. I think it is gremlins in the cars. So many random things happen, especially in the rain.

06-26-2012, 07:15 PM
It's probably moisture getting to the BCM, since it controls that stuff. Could be water getting in the air intake under the cowl up by the windshield.

My grand prix had that issue (minus the trunk popping). There was some weather stripping that had come loose at the bottom of the windshield and was letting water run down into the trap door for the interior air intake. Was filling up the tray where my blower fan was and made the fan and motor rust up and go bad along with my fan speed resistor, and it ran over from there down the passenger foot well and was soaking my carpet.

I'd check that out first. Take off the wiper arms and remove the plastic shield under neath. Look on the passenger side and see if you see anything missing or out of place.

06-27-2012, 07:40 AM
Service your battery ends. My friends tahoe did some weird things with dirty battery ends.