Question about 1996 Cadillac DeVille

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Cadillac battery drains over night

96 deville, battery drains to 10 v after 12 hours, overnight will kill it to the point the cells are dead. had the battery tested with a meter , it ran 0 so i was told there was no drain. pulled the stereo deck out, unplugged the lights in the doors, checked if the light were on under the trunk and hood. I can't figure out what the problem is, please help.

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Go to an Autozone,Advance, or Oreilys for a free charging system test. Have them check the Diodes in the Alternator.

Check the battery case by using a Voltmeter with one terminal on the plus post and the other on the sides of the battery case.

What sometimes happens is the Relays stick and do not turn off. When the Keyswitch is turned off, the Relays stay connected. This is hard to find because the Relays still keep the systems working.

There are 2 other ways to find the problem. In trying to do it yourself, you can work through the circuits by disconnecting the battery and bridging the 2 battery cables with an Ohmmeter. There are only a few things that always remain connected. Like the clock, computer memory, and alarm system.

When the fuses for these items are pulled you should lose the continuity or loop for the connections. Whatever is keeping the Ohmmeter active is the shorted circuit. This requires leaving fuses out of the powerblock as you keep pulling fuses until it breaks the Ohmmeter connection.

Another method is a Dealer wiring link. Wiring on your car is done section by section. The Dealer wiring link connects in between these sections and since the plugs match the factory connection pins, the Dealer machine can identify the individual pin connector that is grounding out. Or it can identify the switch or window or seat motor that is shorted.

Please rate my info.

Posted on Jan 21, 2013

Testimonial: "Great answer friend, since I am in Canada I don't have an autozone, advance or oreilys, I will just have to do it manual and pull fuses out until I find the draw, fingers crossed that its not my altenator, that is an expensive fix over here in canada."

  • fordexpert Jan 21, 2013

    Check out sites for Autozone,Advance,Oreilys,Rock Auto for shipping info to Canada. Another site for used parts is is a Nationwide Salvage Association which offers free parts search and gives you Internet photos, prices, and contact info. They routinely ship to addresses, just check for Canadian shipments. Have Alternator checked first, (It can charge and still have bad diodes}.


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Unhook neg batt cable install test light between cable end and batt terminal if light is on you have batt drain pull fuses untill light goes out thats the circut thats pulling down your batt remember where each fuse goes also clock and raido fuse should be pulled first

Posted on Jan 21, 2013

  • john ward Jan 21, 2013

    Thanks for the reply, will have my mech test it this weekend


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  • 4 Answers

I had that problem on a 87 caddy once and it was the trunk light switch the light stayed on all the time

Posted on Jun 24, 2014

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Posted on Jan 02, 2017

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SOURCE: 1997 deville, battery drains overnight,pin

I've replaced several rear body control modules that go bad and drain the battery. It is located behind the seat, black box about 4" x 5" rectangle. You can use a hand held scanner to diagnose them, the ones I replaced did throw a code. It is complicated and you need a pinout chart to diagnose it with an ohm meter. The ones I got were new and ran around $350.00

Posted on Jun 09, 2011

HD Road King
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SOURCE: 1996 Cadillac Deville trunk pull

There is a switch that lets the motor know that the trunk is closed all the way. This switch may be faulty or not adjusted correctly. Find the wire that feeds the switch and check it with an ohm meter to see if it is working.

Posted on Sep 28, 2010

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SOURCE: Battery drains overnight.

Alternator. The regular inside the alternator has an open diode. Disconnect the battery overnight and it will start the next morning. The alternator will need to be replaced to fix the problem.

Posted on Dec 23, 2009

  • 42 Answers

SOURCE: 1991 cadillac deville drains battery

when you have a problem such as this, i would try to unplug the amp over night and see if any thing changed. also you can take a 12 volt test light and remove positive battery lead. then hook up the test light in series ( the wire end with clip hook to cable that's off . and the pointed end for checking curcuits. goes to battery post. the post you removed cable from .the test light will will be bright if you have a large drain on this should have a small drain for the memory for the ecm in the car. then start removing fuses until the test light goes out or dim.try to leave the amp unplugged during this test. maybe this will help!!

Posted on Sep 21, 2011

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SOURCE: power seat on 96 Cadillac deville wont work after replacing stereo. Any Ideas?

it is not a fuse, it is a circuit breaker in the fuse box, which i believe is under the hood on that car, i would check for bare or shorted wires behind the stereo before doing anything with the power seat.

Posted on Sep 03, 2012

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