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Electrical problem, but new battery and alternator?

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Lethal GST

20+ Year Contributor
193
8
Jun 11, 2002
Suisun City, California
Every now and then when I start my car, the battery and brake warning lights come on. I know this means that my alternator is supposed to be crapping out, but the warning lights only stay on for a few minutes, and the thing is, my alternator was just replaced. I had the alternator tested at Autozone, and everything was okay, and I just bought a battery after my car died on me on the freeway, which I think is due to the electrical gremlins.

The problems are started after I did the fuel pump rewire, but really grew out of control after I installed my FMIC a couple weeks later. I don't know how that could be related, but the pipe from the turbo to the FMIC does pass kind of close to the alternator.

I also noticed that my Greddy TT reads in the mid to high 12 voltage range, but sometimes if I hit a bump or something, it will go back up to high 13s-low 14 range, which is what it used to be back before the car starting having problems. You guys think it could be a loose wire? If so, should I be looking for a loose positive grounding out, or a loose ground wire? I'm thinking of also making a grounding kit in hopes that could be of some help.
 
Luv2rally is correct. They test for voltage and current for a few secs...if'n the needles move they call it good....

Installed on the car is a whole nother kettle of electrons...

The charging system is actually prety straightforward as far as electrical systems go. They can do some pretty strange thing tho, so a little understanding goes a long way towards fixing what's broken.

Alternators have one task. To hold the system voltage stable at a set voltage, regardless of electrical load.

That load can vary greatly depending on conditions.

During the day, headlights and etc.. aren't generally required and demand is low....

At night, in the rain, with the a/c on dehumidify/defrost, it's a whole different ball game.

The worst case scenerio is idling hot with everything on...you can see the result, lights dim and the fan slows down.. give a few revs..and the world gets brighter..

I could easily write a kerbillion words on this subject, but just a few things are really important.

The oe alternators in these cars are temperature compensated...meaning on hot days their output voltage is significantly less than you would ordinarily expect.

If there's any voltage drop or bad connections in the system, you can get some problems.

Starting with the battery, let's check a few things...Is the electrolyte level correct? Are the battery connections clean and tight? If your previous battery was really bad, acid may have traveled down the cables quite a ways, creating some pretty serious resistance. Check the feed line to the front fuse box as well.

Moving on to the alternator. It leads a hard life. It's close enough to the turbo to see some pretty serious heatsoak. It also lives under the powersteering pump in some applications, and has reason to resent it's neighbor to the north...(Leaking ps fluid does all kinds of bad things...beyond just coating everything with gooo.) Let's make sure the harness connections are clean and tight at the alternator case. Make sure the alt drive belt is in good shape, and correctly tensioned. DON'T get carried away tightening the belt!!!!

And finally, on first gens, there's an alt fuse in the front fuse box. It's held in with bolts. These bolts can get loose/stripped and cause some interesting issues as well.

I've had really bad luck with aftermarket lifetime gaurantee parts on these cars. Speaking entirely for myself, I'd rather have my own piece rebuilt by a local electrical repair shop then buy an aftermarket one. You might pay a little more, but you'll get the experiences of the man that's been dealing with automotive electrical issues for a living. They can be VERY helpfull indeed. Good luck.

And remember, it could be worse...you could be working on a 6 volt positive ground british car...talk about issues....:D
 
Hopefully you didn't buy the alternator from Autozone as well. They SUCK! I went through 3 in one year.
 
I did buy my alternator at Autzone! :cry:

Thanks for informative posts and suggestions guys. I had my car on the lift today while changing my suspension, so I had a better angle to mess with alternator connections. I made checked if everything was tight and wiggled the wires around a bit to make sure. I also tried to clean out as much of the goo and road grime that I could. After I started the car, the voltage was up around 14.2-14.5 again. Hopefully everything should be okay now.
 
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