TerpBE

I have a 1999 3.8L Mustang that has been giving me problems lately. Last week the battery died so I jump started it. When I drove it around, I noticed that there was some radio interference, and at one point the electrical system seemed to cut out for a split second, causing several dashboard lights to come on for a couple of seconds. Then, when I turned off the car it wouldn't start again - the battery was practically dead. It seems like it might be a short somewhere. (I had a similar issue last year, but it turned out to be bad/corroded battery terminals, which I replaced).

I've jump started it a couple of times since then, but the battery won't hold a charge. To try to diagnose any potential shorts, I disconnected the negative wire, put an electrical tester between the wire and battery terminal, and started pulling fuses under the hood:



I noticed that the circuit connected to fuse "M" was drawing current, which isn't a surprise since it is the radio, and I assume uses power to maintain the clock and presets. But I also noticed that the tester remained lit up until I pulled fuse "F" - "Instrument Cluster / PCM".

Is there any reason that "F" should be drawing a current when the car is off, or does this indicate a short? If so, should a new instrument cluster fix the problem? For many years my odometer has only lit up intermittently, so I don't know if that might be a sign of a problem.

Does anybody have any suggestions? I think I can replace the instrument cluster relatively easily, but I want to make sure I'm headed down the right path before investing the time and money. Thanks.

-B.E.