[kameroncousins1]

Hey guys, I have a 88 mustang foxbody I'm restoring and have an issue with my starting of the car. So the car will be complete off with keys in my hand and still seemingly drawing unusual levels power from the battery, which kills the battery. But before the battery is dead, if the battery is connected the car will try to turn over even if the key is out of the ignition. It won't stop until I put it in gear and kill it. This happened a while ago and i haven't driven the car since. Now I just replaced the starter, starter relay, and battery cables. Most of the actual engine is fine. I replaced all of that stuff two days ago and it worked like a dream. I've ran it for the last two days no problem. But today after taking a drive it started acting up again. I turned off the car and when I got back in it and it wouldn't turn over. After a few tries of it failing to turn over, it did the same stuff as before and now it won't do anything. No lights, sounds, fuel pump, nothing. exactly like last time. But it's still pulling from the battery. Any ideas, please? I'm thinking I'll have to replace the ICM or the cars computer.

 

[Stustu07]

Start with the ICM and the PIP...

But first I'd unplug the alternators external regulator if it has one if not just unplug the entire alternator and see if the drain goes away...

You should pull fuse-able links one at a time with a multimeter hooked up to the battery.. (They're screwed in by a screw I'm the wire nest near the radiator overflow tank, remove the screw/bolt and take one out at a time till the drain disappears) Then once you figure out the which wire stopped the drain check a wiring diagram and check the associated components...

You don't have an aftermarket or dealer starter do you?

 

[kameroncousins1]

I'll do that. I've wanted to try to look at my fusible links, but there's just so many wires in the car it that kind of scared me. But I'll do that. and it's a stock alt as far as I'm aware. most everything is stock.

 

[kameroncousins1]

If i unplug the alternator and the drain stops, then wouldn't that mean that its the alt that is probably bad?

 

[Stustu07]

It would mean the regulator is bad..

 

[OldTimer Dan]

When was the ignition switch replaced? There was a recall on the ignition switches shorting out back in 2000 - 2002 time frame. My '90 GT did not experience these issues but got the new ignition switch under the recall. Have also had the diodes in the alternator go bad and leak to ground when key is off, disconnect alternator output leads and check for battery drain. Burnt out fusible link won't cause battery drain, acts like a fuse for the circuits it connects to power. It is a good troubleshooting technique to disconnect one at a time to find if one of the circuits are causing a problem. Disconnect the smaller wire from the ignition switch at the starter relay, it's a "push on" connector. Is the wire "hot" (has ~12v on it)? If yes, definitely ignition switch issue, if not, and battery charged and connected, does engine crank? Then stuck relay issue. Never mind "new", just means they haven't been tested yet! Too many parts now-a-days arrive D.O.A. :frown:

 

[Stustu07]

Yup that's why I told him to pull fuseable links until the drain went away and then check anything related to that fuseable link any updates OP?

Also Oldtimer Dan wasn't the recall for the TFI? I never knew about the ignition switch recall... I know the TFI would over hear and cause the car to randomly shut off.. (Ask me how I know lol)

Also I agree a lot of parts arrive broken or useless before we even use them :/

 

[mg man 75]

If had a guess. I agree ignition switch. There was a recall on them. Maurice

Recall info i did it on my year. Can search yours.
http://www.cars.com/recalls/ford/mustang/1989/