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Intermittant starting Problems


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99 Cadillac STS,68,000 miles. Car starts fine for weeks then suddenly it won't turn over, no interior lights, door opener won't work, everything is dead. Had a parasistic test done at local GM dealer's and had battery replaced. No luck. Problem has reocurred. Back to dealer and again no help. Any ideas? No-one has been able to diagnose problem. Battery connections checked. Could this be an alternator problem?



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I'm not an electrical systems expert, but I'll try to help you work through this logically.

The first thing I would ask is when the problem occurs, does the battery have to be recharged?

If it does, then I would look at the charging system (alternator, voltage regulator, etc.). If that all checks out, I would look for lights or other electrical devices that might be occasionally staying on and draining the battery after the car car is shut down. It might be something like a trunk or glove compartment light, heated seat, rear window defroster, something that could sometimes stay on without your knowing.

If the battey does not need to be recharged, I would suspect something in the primary battery wiring (since, when it happens it affects everything). I would check the battery cables very carefully. I would also check the cable connections at both ends of both cables. A loose or corroded connection where the grounding cable connects to the frame could cause the problem you describe. I know you said the cables were checked but this is an intermittent problem and if they were checked while the problem wasn't occurring, they would probably check out OK.

Intermittent problems can be very frustrating to solve. Be patient. Somehwere in your electrical system, there is one flaw that is causing this. When you find it, the problem will go away. I hope this helps.


Happiness is owning a Cadillac with no codes.

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It sounds like you have a drain on the battery, when you shut down car. You need to get a test light , or make one. Don't use a volt meter because it is too sensitive to slight voltage. Take a 12 volt auto rear light bulb and solder the 2 wires to the light bulb, attach ends to big alligator clips. Make sure no lights are on and security fuse pulled out ect. , Now disconnect the negative side of the battery. Put the jumpers betwwen the negative terminal and negative wire. After you do this, watch the light , if it lights you have a 12 volt drain. Most likley coming from a bad diode in alternator , or other appliance in car, such as a cigar lighter, heated seat , anything. Keep trying to shut things off, or disconnect wires or clips, untill light goes out. Then you have found the problem. You can also disconnect diodes, or hot wire at alternator . Be carefull when disconnecting hot wire from alternator, so it does not short to ground such as the body of alternator. Good Luck

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