ange_421

charging problem on 2000 gt mustang
I replaced the alternator, and its still has a drain, my battery light has remained on, I have no power to drive it just sucks thelife right outta my battrey, is there a charging relay under my hood in my fuse box, something that is keeping my car from charging correctly?? i really need help on this cuz ive gotta fix it I have nobody else to help me.. so here i am counting on someone who knows whats up it just started draining my battery when i left yesterday and turned on my lights, i replaced alternator today and its not fixed, watched it charge then slowly loose its charge. and my car died..Help please

Mr. D

I think you are in the wrong section.... but..... I had the same problem with my '08. I was told that some Mustangs have a heavy draw problem when sitting idle for a couple of weeks, and that was the problem! Mine turned out to just be a bad battery that was misdiagnosed! They heard hoof beats & they told me to look for unicorns when it was just a horse! How old is your battery? My point is make ABSOLUTELY sure your battery will hold a charge & your new alternator is producing a charge before you go any further! I'm not sure if a battery is shorted if it will cause your charge light to go on in some cases! Bad batteries can cause really weird conditions on newer cars! If you turn everything off in the car, disconnect the negative cable of the battery & rub it on the negative post of a charged battery you should get only a very small spark due to elements that never turn off like the computer. If the spark is pretty strong & noisy you have a short! That at least might help rule out shorts as opposed to bad electrical components! Also never assume a new part is good, especially if a rebuilt part! Test the alternator to make sure it is really charging. I've run into lots of cases where new parts did not work & that can confuse you! Use a multimeter to check if you are getting a charge in & out of each element from the alternator to the battery if you can figure it out!

You may have to locate a good auto electrical specialist! Good luck!

unitedwestang

The best way, I've found, to diagnose a battery drain is to hook your multimeter on the current setting between the negative terminal and negative lead. Read the draw. Then pull a fuse. See how it affects the draw. If it has no effect, put it back in and continue down the line. If you pull a fuse and the draw drops way down, you've found your culprit. Then look at the electrical compenents associated with that circuit. Google it. Watch YouTube videos. There's plenty of write ups, videos, and websites describing this process in detail.

unitedwestang

IIRC, normal drain is somewhere around 35mV? But you DO have to leave your multimeter attached with everything off for like 20-30 minutes to wait for everything to "go to sleep" in order for it to drop down to that.