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Cadillac Repair/1999 Cadillac

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Expert: - 11/19/2009


Question
Every once in a while like today my wife went to start her car.  It was completely dead. Nothing worked, she called AAA.  The battery was fine so he attached a jumper box and asked her to try an start the car.  The dash lights came on but it would crank the starter.  She turned it off and tried again then it started.  The same thing has happened before.  Any idea what is the issue?

Answer
Hello,

By nature, we all know the battery is key element in power supply for the vehicle. The battery is only one part of a much larger electrical system.

Now, there are numerous possibilities as to what is wrong and without being physically present at the vehicle, I cannot help you. However, the first thing I would check for is a parasitic draw. Very easy to do. Remove the positive battery cable. Put one end of a test light on the cable and the other end on the positive post. If light comes on you have a draw. Go to the fuse box (extra one in trunk)and pull out a fuse. If the test light does not go out. Re-install and go to the next and on and on until you find the fuse that will shut the test light off. Then you know what circuit the problem is in.

Common sources for draw are ant, cigar lighter, dome lites etc.

If test light never came on showing a draw, I would take a volt meter across the battery to see if it is charging. It should be around 14.2 volts. If not, you need an alternator.

If any of this helped, please rate my answer. Thanks,

Rob

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Rob Painter

Expertise

Alarm system questions cannot be answered on this forum. These systems are not what I can answer. Without being physically at the vehicle and not knowing what kind of electrical service has been done on the vehicle, there is no possible way to give an accurate answer over the internet. My expertise is in Ignition/key based anti-theft systems. These issues include GM VATS (resistor chip in key blade) PASSLOCK (MRD)-ignition lock rotation based, no special ignition key and the PKIII Transponder (computer chip in key) systems. These systems are not alarm based and are integral with the starting of the engine. This is why I cannot diagnose alarm problems without physically looking at the vehicle: Alarm systems are a completely different annimal than ignition key/lock based anti-theft system. Many alarm questions come from vehicles 10 years old, and since older, many hands that had been involved over the years.I am an expert in all GM factory (ignition/key based)systems. Alarm system questions pose to many situations beyond my knowledge as to what has been done to the vehicle over the years. Some guy may have actually wired the stereo into the alarm system. Who knows? Over my past 30 years in vehicle wiring repair, I have seen unbelievable wiring disaters done by guys that consider themselves "mechanics." I have seen stereos and alarms intalled using surgical tape. I have seen modules burn up, un-fused circuits, wiring jambed between the doors and even lamp cord used for a starter kill. To answer alarm questions over the internet without examining the vehicle is like asking; What does it take to remove a dent?

Experience

Education/Credentials-ASE certified. 11 years with a GM dealer and 17 years with a repair facility dealing with only the repair of theft recovered vehicles.

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