I know this is not a problem that can be pin-pointed on a forum like this, but any advice would be a help. My 99 DeVille base model drains the battery stone dead if left to sit for a couple of days. It is at the dealer right now, but they are saying they can't find the problem because there are no codes. If a certified Cadillac dealer says they can't find the problem, what can I do? I don't have the skills or knowledge to deal with this myself, so I am resigned to paying someone else to do this, which is okay, but where can I take it? Thanks for your help.

Maybe a leaking rear air suspension system? Thus causing the compressor to run all the time? Just a thought. Have they checked the battery? Could be a dead cell. That would cause the battery to work until it is left unused for a few days. V.

Thanks for the suggestions, Vinny. I forgot to say that the battery checks out ok (its new), and the dealer says the drain is "intermittent", because a test reveals no drain on the battery at the time of testing. How can a drain be intermittent? Does this mean that something is switching on by itself periodically and not switching off? Is there a particular function on a DeVille that is programmed to turn on by itself when the car isn't running and then turn off?

The rear leveling system(air suspension) comes to mind. It will run even if the car is off and sitting, but only if a load in placed in the trunk, sitting on the back, or leaking shocks, etc. Try unplugging the compressor(electrical connection, not the air line) and see if that is the cause. The dealer could hook up a multimeter to check if there is a higher current draw than normal. There should be some draw for the computer, radio, etc. V.

Thanks, Vinny. I'll tell this to the dealer.

I had to replace the Continue to Run module on my 99'. The battery would go dead overnite because the module was bad. It is the module that lets your radio,windows etc. continue to operate after the ignition is turned off and until you open the door. Mine showed no symtoms of any kind. The accessories all turned off when I opened the door but the power was still on and draining the battery.

Thanks, bschelle. Do you know if there was a measurable current drain on the battery before you found the problem?

I think that is called the RAP (retained accessory power) module.

I never checked for the current drain. The dead battery every morning was enough evidence for me that there was a current drain.
Retained accessory power (RAP) is the term for the feature. The main components of the RAP system are the body control module (PZM), controlled power relays, accessory time delay relay and several fuses. If my memory serves me correctly the PZM is what I replaced on my 99'.

I just found the invoice for the repair and it states: shorted N2829 relay-replace engine wiring. Replaced relay #12088567