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Cadillac Repair/73 Cadillac sedan DeVille electrical problems


When I turn on my headlights my tail lights, break lights, turning signal and reverse lights don't work. I changed all the bulbs; fuses are good. Then on top of that my battery won't stay charged, new alternator and good battery. What's going on


It could be your draw to the battery relates to the light problem. I suspect the problem is in the rear lighting harness. Depending on the car and I haven't worked on one of these for 30 years, the harness should attach to the fuse box and runs all the way to the rear either under the carpet or under the door sills. It is possible that this harness could have a problem such as a short and feeding back into another circuit causing the draw on your battery. Another thought is that you have two seperate issues in which the harness has become disconnected at the fuse box, but that issue which needs to bechecked out as to why power is not going to the lights from the fuse box. The  draw is easy to test for. Disconnect the positive battery cable. Place a test light between the disconnected cable terminal andthe positive battery post. If there is a draw, the test light will be illmuminated. One at a time remove the fuses and reinstall until test light goes out. That will tell you the problem circuit however you may not know what all is on that circuit for the exact problem of which you would have to obtsin a Cadillac service manual from Ebay or Craigs. My experience for a common draw issue was cigar lighters. Commonly the rear because they faced flat and downward collecting moisture. Check the rear harness before anything else.
Good luck!


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Rob Painter


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?


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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