I have an 87 LX 5.0. Yesterday my AMP light came on and I noticed that my battery gauge was way down. I barely got the car home. I took the battery to a local shop and tested it -- they said it was no good. Bought a new battery and installed it. Same problem. AMP light is on... gauge is down in the red... even though the battery is new. What's my next approach? Alternator replacement? Just seems weird that a brand new battery starts off in the red... Thanks for your help! EDIT: Oops, this should probably be in tech, not talk, right??
you should get your alternator tested. Take the car to autozone or advanced and they can test it in the parking lot. Check the ground on the alternator, and the plug on the side of the alternator, a lot of times that plug gets brittle and the clips break and it will make a poor connection. Or you can start the car and take the ground cable off of the battery while the car is running and if the car dies it is most likely the alternator. Then you can take the alternator off and just take it to advanced or autozone and just get it tested. It will kind of narrow down your search.
Never disconnect the power or ground cables from the battery with the engine running. The resulting electrical spike can damage the computer, radio or other electronic devices in the car. If you are going to replace the alternator, use a 3G from a 94-95 Mustang. It is a 130 amp alternator and should have been standard equipment on all 5.0 EFI Mustangs. See http://forums.stangnet.com/showthread.php?t=646825 for complete details on how to do it.
