ok well every time i step on the brakes my lights dim WTF. i just had my alt tested today and they said it was running fine. so i dont get it i just dont want to be chillin on a free way and they bam no more light or something

 

what is the voltage when this happens?

 

i just took it for a test drive after doing a good hr charge on the battery. and i took it out and had my fog lights on, my cd player high beams on and it read about 12.5 (right above the 12 line) then i turned my rear defroster on and it went down to under 12 maybe 11. i am not sure what is happening my heater isnt working ether and when i told the guy about it that i bought the car from he said it worked fine. so i am not sure i just hope i dont have to play find the bad wire. i was just thinking it was the alternator, maybe it ok just not strong enough.

 

any time the voltage drops under 13.5 the battery is no longer being charged, and if at any point the voltage is dropping under 12.5 the car is running on the battery.

You have a bad alt

 

that is what i was thinking too maybe i should get a second opinion. is it possable to have a bad ground somewhere ?

 

^^^ that is also possible, and cheaper to check

 

Also check the thick wire that runs from the alternator output to the fuse box. More then once I have seen them burned all to hell at the terminal which will produce the exact same symptoms...

 

thanks i will report back when i checked the wire and the altnator again

 

Personally, I don't trust the stock voltage gauge.

Mine never reads above 13. I have a reman alternator with less than 500 miles on it and have never had my battery die on me for the last 4000 miles (except when I left my lights on). My gauge has always sat that low.

Unless that means there's another problem I have...

 

do you think this would help my problem? http://www.vividracing.com/catalog/p...ducts_id/13196

 

only if your problem is more money than sense

 

ever tried tightening the belt? i had this problem not too long ago '90 GTU - i had a good alt and a new battery and my battery kept getting drained. i almost went crazy until a buddy of mine suggested tightening the belt, so i did and the problems ceased.

 

When you test it from the alternator, do you still get the ~12.5V? Like I said, I wouldn't trust the stock gauge much.

 

no i am still looking for my volt meter. as of the belt i tighten it down pretty good. i know it not good to have it too ttight but it has a little bit of play. but i will try it again who konws maybe i just suck

 

Im going to go out on a limb here and say you've got an S4...........

Upgrade the alt. to either an S5, or best, an S6 (FD alternator) You'll never have any charging issues unless the thing seizes up on you.

On my DD I have had the alt. fully rebuilt and still had charging issues, its just not strong enough to deal with the load....not to mention that by now I imagine the resistance across the ENTIRE wiring harness is slightly more then the day the car left the factory - so everything takes just a tad more juice to run.

After an FD alt. swap - I've got no problems, other than the pulley im using is too large and I run on battery when idling.......