View Full Version : Alternator help

03-30-2010, 11:46 PM
I bought my 1999 Camaro SS about a month ago with around 60k miles on the alternator. I installed my amp and a capacitor which Iím not too sure if installed correctly, its digital reading changes from 11.8 to 12.4 from what Iíve seen. But back to my original problem, my battery volt gauge usually sits at 13-14ish when I start the car but when I place it in gear it drops down to around 10ish then when I start moving it goes back up to 13-14ish. Shortly after I bought the car I was looking around the engine and found a red wire that went to my alternator that was just twisted together to a red wire that went into a wire bundle but not too sure where to, I crimped it together vs. it just being twisted together. Anybody have any idea what that wire was and if my alternator is bad or if its something different? And any help with the capacitor problem if It is one would be nice also.

04-01-2010, 10:41 AM
What was your intent with the capacitor?
There are many types of capactors, but the important thing here is was it polarized? Look for a positive or negative marking. Positive goes to hot, negative to ground. If there's no markings, it doesn't matter which way it goes in.

You alt sounds like it's not spinning fast enough with the car idling. Do you have underdrive pulleys? If idle RPM is correct, and you don't have UD pulleys, then something is wrong with the alt.

04-01-2010, 01:15 PM
My intent with the capacitor was to prevent headlight dimming, and I am not sure about the answer to you pulley question could you please explain a little more.

04-01-2010, 01:50 PM
Anybody have any idea what that wire was and if my alternator is bad or if its something different? And any help with the capacitor problem if It is one would be nice also.

that is the output wire from the alternator and gets spliced into the hot side of the ignition system within the wiring harness, basically it gets hooked up to battery positive. Without looking up the wiring diagram in a service manual i can't tell you exactly where it goes or what wire it gets spliced into, but it usually gets spliced into a main feed running between battery positive and the starter. if that's not connected, or poorly connected, you will have piss poor output from the alternator... because the output wire isn't connected. It sounds like work had been done and the wire got busted or cut and they did a bad job to fix it. You should either have it soldered and shrink tubed to insulate it or use a good crimp and shrink tube that.

How do you figure the capacitor would help with headlight dimming?
It might... remotely might... prevent flicker or pulsation. and if you had pulsation that would be from the alternator's voltage regulator and/or rectifier going bad in which case needs to be replaced.
like was said, if the car has an underdrive pulley which is a smaller aftermarket crankshaft pulley that had been installed to get a little more horsepower by reducing parasitic loss by turning all the accessories (alternator, ac compressor, power steering pump) slower then the alternator is turning slower which results in not enough power output and if you have headlights, heater, and radio going at idle rpm the voltage will drop below 13v.
The other case is the alternator is on it's way out, provided it's wired properly and no other wire connections are bad. And unless you know how to replace the rectifier and/or voltage regulator in it then you just swap out the whole alternator for a new one at the parts store.

04-01-2010, 02:18 PM
Check charging voltage at the alternator.

04-03-2010, 06:11 PM
Hey Moto! Just like The Shop said, put a multi-meter on the posts of the alternator at idle and see what you have. Then shut the car off and put the multi-meter on the same posts on the alternator, you should have less voltage...this will tell you if it's cranking anything out. After that, you need to trace down the mysterious red wire and find out if it's attached to anything on the other end...let me know.

04-04-2010, 12:17 AM
Get rid of the capacitor, upgrade the big3, and test alternator.