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Discussion Starter · #1 ·

I bought a used 1989 BMW 735i. This car is having a "small" electrical problem. When I start the engine and then kill the engine, get out of the car and close the doors...about one minute later the gonger will gone once or twice every 15 seconds or so, usually accompanied by the Instrument Cluster LCD read out back light will flash some times before, during, and after the gong.

The battery voltage when not running is a little over 12 volts. When running, the alternator is putting out 13.84 volts. When the car is off, the electrical system is pulling anywhere between .38mA and .45mA. When I pull fuse 20 (the Instrument Cluster and Anti-Theft protection fuse), the current draw drops to zero.

Sometimes, after the car sits about 24 hours or so, I turn the ignition to position 2 (not starting) and the Instrument Cluster LCD displays in German. When I disconnect the battery for 10 seconds and reconnect it, the readout is in English.

I have pulled the Instrument Cluster and replaced the 22uF and 220uF capacitors mentioned by "shogun" and inspected the PC broard for broken solder joints and burned traces. Everything looks good. And, I have reseated the Instrument Cluster wire harnesses.

At first, I thought I was dealing with a parasitic battery drain. Now, I think it is the Anti-Theft module "thinking" the car is being "woken up", or maybe I have a grounding issue with the Instrumentation Cluster, or maybe I have a back noise capacitor somewhere.

This is a project car so I am using this to brush off the frustration of work, and to learn about BMWs.

What I am looking for is primarily information from other 735i owners who may have seen similar symptoms, or might offer suggestions on how to start eliminating sub systems to isolate the sub system that is causing this.


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