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Cadillac Repair/1989 cadillac deville battery drain

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Expert: - 10/7/2010


Question
how do I determine what is draining battery power.  If the auto is not driven for a few days, the battery power is not enough to startn the vehicle.

Answer
Hello,

First get a 12v test light. Disconnect the positive battery cable. Place one leead on the battery terminal and rhe other side on the positive cable. If the test light is iliminated, you have a draw.

Remove the underhood bulb and if the test light is still illuminated, you need to go to the passenger compartment. If possible, have someone watching the test light for you.

Now, you don't car about switch powere circuits like the wipers or radio.

You need to remove a fuse one at a time. Close the door and see if the test light goes out. The reason I tell you to close the door each time, is that too will show a draw. Keep pulling the fuses and reinstall while watching test light.

The minute you pull a fuse and the test light goes off, that is your problem circuit.

In the event you have not found it, then pull the dome and then the courtesy light fuse.

If there is a draw you will find the circuit this way.

I will just give an example here. Lets say the problem is found on the dome circuit. The cigarette lighters are on that circuit. All lighters would be disconnected and the dome lamp removed. Each lighter would be connected one by one to see if the test light stays out. The last lighter you plug in turns the test light on. That tells you tge lighter is the souce of the draw. Now say all the lighters are connected and test light is out. Now you reinstall the dome buld and test light comes on.

That tells you something is wrong with the dome wiring. Maybe a vad door pinswitch.

Good luck! If my answer helped you pleade rate it.

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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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