Ground issue, or something else?

Pressing on the brake pedal* not depressing it..

chech you connections and the ground in and under the trunk sounds like the bumper moved enough to disturb somthing

Could it possibly be the body control module? If so, where is it located in the car?

when you open your trunk, there should be a wiring loom that runs along the hinges. try the wiggle test on it with lights on. trunk release, lic plate lights and running lights, all rear trunk area related, prolly bad wire, ( stretched and broken insulation ) in that loom that runs along the hinges into trunk lid. keep in mind that is a general diag, im a euro tech and not familiar with GM products. definatly do not go replacing a BCM yet, i highly doubt that, that is the problem.

I've had a similar problem, for you maybe a coincidence this may have been a problem b4 you bumped your wall, check the wire harness for any burnt up wires, as far as the trunk is the trunk release intact? its located just above the latch maybe 8 inches from, if its broken that's your problem there as far as the trunk, as for the rest something electrical. The body control is under the back seat or to the left under the hood look in your manual. If you don't have a manual you can get a .pdf online just type year ,make, model owners manual one should come up, good luck.

also it's unusual that both reverse lights go out at the same time, know that.

I have checked all the wiring in the back of the car , no burnt wires or broken trunk release... And this morning I noticed that the heated seats are no longer working as they were the day a this began.. There has never been any lighting issues up until now.. I check all lights daily as it is habit for me to do so... So could it be the BCM, or a serious electrical problem that could potentially cause a fire?

Just noticed that now the heated seats are no longer working, the auto dim mirror is no longer working, and tonight on my way home from work that a message " service electrical system " popped up.. Voltage is at 15.1 idle, and running it drops to 14.6... so I do not believe it to be an alternator issue. Could it possibly be the BCM going bad slowly killing one component one at a time?

I have the same problem! With the car in reverse and the engine off, I open the trunk and slowly close and open it and the reverse lights come on and off, if i hold it at the position when it comes on the reverse lights will stay on until i move it from its position. The licence plate light will do the same! I still dont know what the problem is! Can anyone help me?

I have an 04 DeVille with similar weird electrical issues. Like the trunk intermittently not opening with the remote or the interior trunk release. Also cruise control cutting out when I turn on the wipers. Also the traction control not working intermittently Also drivers side electric seat not working intermittently I suspect a ground fault but am unsure as to how to fix it

For those of you who have experienced the same or similar issues, check along the left trunk rail on the lid. thats where I found two severed wires that i was able to correct my situation