2005 Cadillac Deville dies when any light is turned on
Asked by Lee May 21, 2022 at 09:41 PM about the 2005 Cadillac DeVille Sedan FWD
Question type: Maintenance & Repair
Engine stalls when you turn any light on including
blinkers and hazzards. I know it's got to be a ground
issue, just hoping someone has dealt with this and has
a solution for me. I read somewhere that the ignition
switch could be the issue. So I replaced it since it was
very loose. That did not fix it. Any help would be
appreciated, thanks
14 Answers
beatupchevy answered about a year ago
Look for good motor to chassis ground or obvious wiring problems ,
Sounds like a bad ignition system ground. Do you have any lights, that aren't turned on, glowing dimly? Anything on the vehicle that's not working or not working correctly? Check those circuits first. If you have a bad ground electricity will "hunt" for a ground and cause lights to glow dimly, etc. Also, if you have an aftermarket stereo, check the wiring for that too. They're often the source of electrical problems. Hope that helps! Jim
The battery stores electricity for starting the engine and after the start, the alternator takes over. It charges the battery, runs the engine, and provides about three volts of electricity to the car to run the lights and other things..... When the engine dies when an accessory, like lights, is turned on, it's often caused by two problems: Defective alternator and weakened battery..... You might have a good battery, but the alternator just can't keep up with everything. Accessories steal juice form the engine and the engine starves for electricity, so it can't run properly, or at all, as in your case. If this goes on long, it damages the battery, too.... Just check the alternator and the battery.
Check the battery cables and the power distribution box. It is a long run from under the rear seat cushion to the engine compartment so you could have a problem almost anywhere.
When the ignition is on, the mirror turn signals are lit up. Other than that, all lights seem to be normal. When I pull the park lamp relay, I can turn the lights on, but blinkers will still stall the engine
Another fun fact. Disconnected head lights, and when I turn the headlights on and use the blinker with key off, instrument cluster lights up like the key was switched on
All this still sounds like grounding or distribution issues.
I guess my biggest question is "so don't replace BCM?"
It really doesn’t sound like a BCM problem, it won’t cause the engine to die out. Besides I doubt you can find one right now, I’ve been waiting for over 12 weeks for a BCM and it still shows on national back order. If you really think it’s a BCM problem you might consider a reflash.
Honestly, I'm with you on it not being a BCM issue and it being a ground issue. I'm assuming the headlights are in the CAN system because with both headlights disconnected, engine won't crank. Sorry for all of the questions. I'm a diesel mechanic, wiring issues are a lot easier with Diesel does anyone have a wiring diagram?
If you can’t find one on the internet then try your local library in the reference section and see if they carry the vehicles shop manual, if they do have the wiring sections copied from the book.
So I guess my next question is, am I looking for an improper ground or a short to ground issue
The way things are acting I would say an improper ground. Now these Cadillacs are ground crazy and they all must be good or you get feedback like what your experiencing. After we got rid of out last Deville we decided no more Cadillacs.
So I found the issue. It was a ground distribution block by the front right headlight. It wasn't bolted down lights work fine now. Thanks for everyone's help and advice
