Okay here's a tough question (or not). I drive a 93 Ford Mustang,
1.4L. For a while there has been a short in the electrical system, forcing me to disconnect the battery every time I shut off the engine, so as not to let it drain. I believe the short is being caused by the car alarm. I am not sure how to locate the alarm system and disable it, or if the short is somewhere else, what tests to do to locate it. I know the short is not caused by the alternator, as is sometimes the case. thanks in advance
Zach Borst opined in news: snipped-for-privacy@posting.google.com:
I'd worry MORE about the 1 and 1/2 cylinders you seem to be missing..
Did you mean 2.3L?
Get a test lamp...put in series with the neg battery cable, remove the fuse links from soleniod one by one till lamp goes out. thats the circuit... will prolly go to the fuse block. Find the connection to the alarm unit and remove ... or find alarm unit and work toward power.
The alarm shouldn't be that hard to locate, especially considering how sloppy a job most install shops do these days. Seems to me the most common spot for installing the alarm brain box for Mustangs around that year was above the stereo, behind the ventilation controls... I've seen more than one shoehorned in there, might be a good place to check. But otherwise, you should be able to follow the various alarm wires to the source... usually the wires that sense the opening of the door/hatch/whatever are pretty easy to spot since the alarm installed likely didn't go to extra length required to really conceal things. As the wire style won't match the normal Ford wiring, it should stand out. But again, if that doesn't work, try following from the alarm's siren which is probably mounted under the hood someplace, maybe by a fenderwell. Also check to see if power wiring for it was run straight to the starter solenoid. It really should have its own fused power line, which if it does and you can find it you can just pull the fuse and see if that solves the problem.
Otherwise, you could start isolating the problem by pulling fuses for individual circuits and seeing when the leak goes away. It's a slow process, but it would at least isolate which group of circuits have a problem. In that regard a fairly sensitive ammeter hooked into the power line for the sake of testing would be useful... hook it up and start pulling fuses until you see the flow of current out of the battery disappear. Or if you want to be more anal about it disconnect the circuits at the point of the fusible link since that would eliminate leakage past the fuse block, although that's rather unlikely anyhow. A good place to start is with circuits you know aren't switched off when the key is removed; power locks, mirrors, things like that. It's not guaranteed that the switched circuits aren't leaking, but it's a safe enough assumption to make when starting your diagnostics.
I'd agree that starting with the alarm is a good choice, though. Anything not part of the factory wiring schematic is pretty much always immediately suspect.
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