I have a 04 Deville. Yesterday as I was about to leave for the morning, I had placed my car into reverse without thinking, and backed into a plywood wall separating my garage from the other one.. No damage to the car, no damage to the separating wall.. I noticed as I returned home yesterday evening that my reverse lights were not working,upon inspection I found out my license plate lights were not working but coming on instead when the car was in reverse and the trunk was open.. Today as I headed out to go to work I went to pop the trunk to place some things in there, and you could hear the solenoid clicking but it wouldn't release, after several attempts it finally popped the trunk.. ( Keep in mind that the trunk of the car never hit the plywood separating wall and it was merely a small bump.. ) and now the inner bottoms of the tail lights have a section that will not light up ( sort of like a 2x2 square cut out ) yet the rest of the tail lamp will remain on as if I am pressing the brake pedal... The tail lights operate as normal when I have no lights on, the reverse lamps as well as the license plate lamps are completely screwed up no matter what I do, and the third brake light, well lets just say, I have seen brighter colors out of a box of crayolas ( i.e Its not working either ).. Am I suffering from a wiring issue, i.e Broken Ground Connection? Could it be a
solenoid on the transmission that has gone bad? Maybe the trunk solenoid is going bad? It wasn't a hard enough bump to hurt or even leave a mark on the car or the brace on the wall I bumped, and it still does not explain why the license plate lights come on in reverse and when I pop the trunk rather than my back up lamps and trunk lamp, and why the brake lights are not working properly... If anyone has any Ideas, I would greatly appreciate it as I am about to drive this thing off a cliff and say good bye to Cadillac for
good!


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 on the rear view 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 when driving... 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?

 

There are codes stored most likely. See FAQ to see how to access them. Also check fuses, fuse box is under rear seat bottom.

 

The codes I have managed to pull are Ipm B1004, Ipm B1327, Pcm 1574, Rcc B1009.. checked all fuses and none are blown.. however, I did notice that the battery is a mere 475 cca.. could be that the battery is on its last leg, ( although it seems to be holding quite the charge )

 

the smaller battery could be cause of your b codes. the P coded related to stop .lamp switch circuit