Electrical Issue


New Member
Feb 8, 2007
I have recently bought a '90 Mustang Convertible. It's a 5 speed with a few upgrades on it. I have only had the car for 4 weeks and have found a problem. The battery keeps going dead on me. Alternator right? WRONG! I went the hard way and checked out the altenator. It's good. Then I bumped the window button with my elbow one day while getting into the car. Walla, it works with out the ignition being on, along with the rest of the electronics that should not work without the key being turned. (Radio, door locks, etc.) So if someone could point me in the write direction on what's hooked up wrong it'd be greatly appreciated.

:bang: Something I never thought of checking was if the stuff works when power ISN'T suppose to be going to it! I guess now I've learned.:bang:
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Typically it is something draining the battery. Small things like glove box or courtesy lights are often the culprits. If you have an aftermarket stereo or alarm system, it is also suspect.

The ideal method is to disconnect the positive terminal, and connect a Digital Multimeter (DVM) between the positive terminal on the battery and the positive cable. Set the DVM on a low current scale of 2-5 amps if it doesn't auto range. Watch the current draw, and then start pulling out fuses. When you see a sudden drop in the current, that circuit is the likely culprit. Note that the computer, radio & clock will draw less than 1/10 amp to keep the settings alive.
Oh yeah...Another issue. I just got my car back from an auto shop that I thought would have been trustworthy since they display their cars at all the auto shows around the U.S. I had them put in a speed-o gear (which they said was missing)(my speedometer wasn't working, but the guy I bought it from and still talk to swears he put in a gear) After Paul's High Performance put it in and got the speedo working I paid and drove home and parked the car. After the car sat for a month I get it in and drive it down the road and the speed-o quits about 1/2 mile down the road. Any ideas what the problem is. I would rather fix it my self than take it to another mechanic. It seems that whenever I take one of my vehicles to a shop it breeds more problems. The only reason I take them to mechanics is because I have yet to find a place to work on them. It's a bit cold in Michigan this time of year to working on 'em outside.
Also look for the speed-o cable to be melted. Sometimes they fall out if the clips that hold them in and lay on the exhaust pipes and melt.

That is a good idea. I've never even thought of that. I'll have to check that out. Thanks :hail2: That is the most off the wall answer I have ever heard but yet it sounds so right. I'll take a look this weekend and let you know. Just one more time here ---->:hail2: