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HELP! electrical problem mystry

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I have a 1996 Cadillac Devile Concours. This problem started several years ago when the original alternator failed on the vehicle. It was approximately 30 below zero and went to start the car and the battery was dead and obviously frozen. Replaced the battery and checked the charging system and it showed that it was charging less than 12.5 volts. Replaced the alternator with a NAPA rebuilt. It lasted about 3 weeks and failed. replaced it again. It lasted a little over a month and this time the new battery froze again so another new battery as well. Over the course of 6 months and after 4 rebuilt Napa alternators and 3 batteries we were finally able to locate a new alternator. During the course of all this there was times that the battery would intemitently end up dead and after recharged the charging system would work fine. Thinking there may be a draw on the system it was tested after each altenator replacement or dead battery condition and passed all the tests as outlined by the service procedure. The new alternator has lasted over a year now but still had the dead battery problem on a intermitent basis. Just recently it got to where that if the vehicle sat for 2 days the battery would be dead. In searching for a draw it was found that indeed there was a draw on the BODY 3 fuse in the MaxiFuse/Relay Center. Then the draw was traced back to the rear compartment fuse block to the fuse named COMFORT which controls the CD player, Remote function actuator (RFA). Controlled Power relay, Air control module (ACM), & the PZM (Platform Zone module)-Body computer. Also during this time that the problems were occuring the air ride suspension would quit working intemitently for no apparent reason. We also searched for bad grounds during all of this too and found none. Also there would be times that the turn singnal indicator lights would slightly illuminate slightly and intemitently. Also the voltage indicated at the battery was approximately 1 volt higher than the voltage displayed on the dashboard display.

My question is, does this sound like a failed PZM (body computer) or controlled power relay? And is the controlled power relay a separate component or a integrated part of the PZM? Any help would be greatly appreciated.

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I think you are talking about the RETAINED POWER CIRCUIT, see this link:


If you still have the NAPA alternator, and you are still having charging problems next time you replace it replace it with either a NEW OEM AC DELCO or an AC DELCO rebuilt unit... We have not had a lot of success with aftermarket alternators. Mike

Pre-1995 - DTC codes OBD1  >>

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Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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The battery cable may be part or all of the problem. The positive cable is actually three cables, one going to the alternator, one going to the starter, and one going to the power distribution point on the maxifuse block under the hood on the driver's side. A common problem is poor contact between these cables at the battery. I suffered under this due to a pulled-out battery post at low mileage for nearly 100,000 miles before I replaced the battery cable. It mimics a myriad of problems. The poor contact can be at the ground cable too, either at the battery or at the ground connection(s).

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