overcharging alt

[msgsupra84]

This morning on the way back from dropping my wife off at work, I was doing about about 70 on a 3 mile long bridge, she was just purring, running pristine. I looked down and noticed the alt running about 16 volts (little black mark between 12 and 18). NO LIGHTS. I went to slow down upon a red light and the light flashed for a split second and I put down on the clutch and started braking, the volts dropped down to about 13ish. When I took off the gauge gradually rose to 16 again, but while traveling to 16, the light would come on, go off, come on, then go off and stay off depending on how many rpms I'm at. I figured volt reg but is there anything else it could be? 4 month old battery, the alt is less than a month old, starts fine, runs fine.

[Donn29]

Alternator probably needs a voltage regulator, which should come with new brushes. Not to hard to change yourself. Bring it to a alternator repair shop.

[tyrantfour]

i would check the terminals. ive seen some weird things happen with dirtry terminals. but if its charging at 16 volts its the alternator. setup a dvom on the posts to see whats its really doing.

[celipra]

If you bought the alternator less than a month ago, couldn't you just take it back to where you bought it and get it replaced with a working one? For example, I know Autozone has a lifetime warranty on their alternator for the 5mge(I know this because that's where I got mine).

[msgsupra84]

Yeah I have a new one coming in today from advance, but this will be my third one. I replaced the original back in april due to overcharging and blowing efi fuse, got a reman from advance, about two weeks ago the volts were dropping on the interstate and lights were dimming then it shut off and acted like the battery was dead. About five minutes later it cranked fine but the volt light was still on. I replaced it and now this one charges at 16 after the engine warms up. I feel like I have bad wiring somewhere but not sure where to start because I know it can't be limited to just the alt to bat cable and the ground.

[RedP85]

specs says 13.5 to 15.1
http://www.cygnusx1.net/Supra/Librar....aspx?S=CH&P=4

[msgsupra84]

Just put a reman alt on 20 minutes ago, which is number 3, and now its out, no charge to the battery at all, I'm really desperate for a solution, this is my only car and my wife gets off in less than an hour, urgent help is needed.

[RedP85]

in the link above check the pages after it.
it gives checks instructions and fuses..

[Donn29]

Get a oem alt and have it rebuilt. I skimmed the part where you said it was only a month old..... I have no idea why those Non-ND alts don't work most of the time.

[quickeddie79]

lookin to find out if thay maid 85s in ttops or tagatops thinkin i might try to make mine a taga top .... aney info a plus.....