Cadillac Repair: 73 Cadillac sedan DeVille electrical problems, auto theft claim SIU investigation EOU consultant/expert

Question
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

Answer
Hello,

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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