I drive a 91 STD hatchback. Two weeks ago I installed a brake master cylinder and booster from a GSR with ABS. My brakes are great now, but since that install I've been having an electrical problem I hadn't had before.

When I tried to start the car after installing the booster/MC, I found that the battery was completely drained. I discovered that my brake lights had been on for three days (I hadn't adjusted the brake light switch). The charging system hasn't been working properly since.

I can charge the battery with a plug-in charger for two or three hours and the car will start, although it doesn't crank as hard as it should. But if I drive the car and then turn it off, it won't start. I've been driving it to work for the last few days and just pop-starting it every time. For the most part, it runs fine once it's started, but the lights dim when I let off the gas, and the heater fan speed slows as well. And on hard accelerating from idle, I can sometimes hear a belt squeal. Could I just need to tension the alternator belt? Or does this sound like something else? I'm getting pretty good at replacing parts, but I think diagnosing an electrical problem like this is still beyond me. If anyone can help point me in the right direction I'd appreciate it.

 

yeah try tightening the belt or replacing it if its old, otherwise it sounds like a voltage regulator problem, its inside the alternator.

F.Y.I mine did something similar but it turned out the battery was bad and me constantly jumping it off killed the alternator, try to find it soon!

 

Update: I brought the car to Advance today, hoping that they could test the whole starting/charging system. They couldn't run the whole test because my car won't start by itself (and I had no car with which to jump it) so I just asked them to test the battery again. And what do you know, it tested bad (more specifically, "bad cell").

I mentioned that the same battery had tested "good" on the same tester last week, and the guy said that if my battery had been tested immediately after being charged (which was the case) that the test result might be skewed.

So maybe my problem is as simple as a bad battery. But I'm curious why it failed when it did. Could draining it have made it go bad, or could it have already been failing?

 

I'm going to replace the belt, whatever happens. It's cheap and I have no idea how old it is.

Maybe I've got the same problem (bad battery). Am I going to damage the alternator if I keep pop-starting it and driving it with a failing battery?

 

oh yes you will do damage i actually started to burn my alternator wire, the terminal was white, get a battery cause the testers usually dont lie, the reason your alternator will die with a failing battery is its trying to charge the battery to around 14 volts, and since the failing battery is internally shorted (which is the process going on in your battery) it will try to full field ALL THE TIME to try to charge that battery resulting in it burning up.

also your pretty much running the car on the alternator alone which is not good

 

I bought a new battery today. The car is behaving normally now, not surprisingly. I'm going to keep a close eye on it though. I picked up a new alternator belt too, though I haven't yet installed it.