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My wife's 97 SLS keeps killing batteries... 2 in 2 months' time. Both times the car sat for 3-4 days while she was off on a business trip, and she came home to a dead car. Both times, the auto parts store popped the battery on their charger/tester and proclaimed the battery as "dead... can't be charged".

We hooked up a power supply to the car and started to troubleshoot it... set the power supply to 12VDC at 1 amp, powered it on, and the needle pegged at 1 amp. So we started pulling fuses until the needle dropped, and we have the current drain isolated to the 10 amp "comfort" fuse. (With the breaker pulled, the system only pulls 150mA.)

When re-installing the breaker (in the trunk), the A/C Compressor relay clicked a couple times, which I found odd since the compressor has its own 10A fuse under the hood. So I think there may be something messed up with the A/C circut, but what I'm not exactly sure.

We don't have a shop manual or Haynes manual on the car yet.... anyone know what systems are on the "comfort" circuit that may be pulling over an amp of juice? A schematic of that circuit would be nice too.

The only thing not OEM on the car is an iPod2Car kit that I got her for Christmas last year, which plugs into the CD changer connector in the trunk.

Any help would be appreciated.

Thanks!
 

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White Diamond '03 DHS (with DTS floor shift)
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The only advice I can give you is forget the Haynes manual and get a FSM by Helm Inc.
 

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I have a similar situation with my 1997 Cadillac STS. I have been troubleshooting it for about a year.
Here is what I have found:
The amplifier to the Bose stereo, found behind the back seat in the trunk, is draining the battery when the car sits. When I unplug the smaller of 2 wire harnesses from it, the battery holds charge fine. However, the stereo has no sound as you would expect. It appears that the amplifier is working fine, but the power to it is not turning off when it should. If I find the source of the maintained power problem, I will post it. Currently, I have removed a large gray colored potter & brumfield relay that you will see to the lower right of the amplifier at the trunk floor level. When I pulled it, nothing seems to be affected. Hopefully, wishful thinking, this relay is intended to hold the amplifier on for cell phone amplification or some other function. Only time will tell.
 

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Re: 97 Cadillac Seville SLS STS drain drains battery from "comfort" circuit

I have found the problem for my car. The relay that I pulled in the recent post is called the RAP relay. (Retained Accessory Power) It's design is to keep power to the audio system for cars which have an integrated cell phone installed. It must be controled by the cars' computer. My relay was actually OK, I took it apart and checked it, but the computer is telling it to stay energized too long. There must be a major glitch in the programming of at least the 97 Sevilles and who knows how many other models. Since pulling the relay from the car, the battery is holding charge fine. Too bad Cadillac has not recalled for this issue. Anyhow, although it doesn't solve the actual issue of the programming for the car, pulling this relay solves the battery drain without noticable side affects ( unless you have an integral cell phone and talk on it without the key in the ignition).

To find this relay:
Open the trunk.
Remove the carpet liner from the roof of the trunk. there are 4 plastic retaining nuts you unscrew just behind the upper lip of the trunk.
You will see a large black plastic wall against the back of the rear seat.
There are 4 stud/nut retainers holding it in place.
2 in the upper corners and 2 about a 1/4 of the way up from the trunk floor and about 1/3 of the way in from the edges. You will be able to see this large gray relay through an opening in the lower right of the black plastic wall.
Just tilt the wall down, and unplug this relay. The connector has a black squeeze clip that must be depressed to disconnect the relay. See if it solves your problem, then put it back together.
Hopefully this will help you too. It took me a year to solve this. The posts on this website have helped me to finally get it .
Good luck.
 

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Another update:
Pulling the RAP relay disables the power to the power locks.
I will keep investigating for a work around.
The battery is still holding a charge!!:)
 
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