Alternator test OK, but not charging the Battery (Page 1/1)
robmorais MAR 22, 08:58 PM
HELP.... New to the Fiero.... I had my alternator checked when it was IN the car and it showed that the battery was not charging. I put in a new alternator and a new pig tail plug. I tested both the Pos and Neg resistance and get a Zero reading. BUT i still get the VOLTS light on when I start the car and the battery will not charge. When I run the car the Voltage drops from 12.6 down to 11 or 10 when I turn on any accessories. I also tested the ground by putting the Pos side of the meter on the battery and the neg on the Alternator case, and got the same reading as testing the battery terminals themselves.

What am i doing wrong??? Please help!

Thanks!
Rob
theogre MAR 22, 10:40 PM
What year etc.
What alt used since said need new pig tail.

1 wire of pig tail runs to alt output directly on 85-88. (slice near terminal of big output wire.) And should always be "hot."
other goes to alt light and alt light on dash w/ rest of "idiot lights" and must work or alt won't turn on.

[This message has been edited by theogre (edited 03-22-2021).]

robmorais MAR 22, 10:53 PM
Its an 86 SE with the 2.8 and Manual Trans.

I replaced the Alt and the pigtail.

Patrick MAR 22, 11:37 PM

quote
Originally posted by robmorais:

Its an 86 SE...

I replaced the Alt and the pigtail.



Still not enough info.

Usually the pigtail is replaced on an '85-'87 Fiero when the 2.8 is converted from the original SI alternator to a newer style CS unit. Is this what you did?
robmorais MAR 23, 07:04 AM
I replaced the pigtail because when i unplugged it from the old Alternator it basically fell apart in my hands.
fierofool MAR 23, 12:48 PM
Replace the bulb in the Volt light, again. If it's blown or weak, it will not charge the battery. I had the same issue, and when I went to Advance for a new alternator, a young girl clerk told me. Saved me a bundle.

[This message has been edited by fierofool (edited 03-23-2021).]

robmorais MAR 23, 05:16 PM
OK - I replaced the belt with a new one, started up the car and it is giving me over 14v when running. However, the VOLT light is still on.... I know that the PO had messed with the electrical system and put in some random wires with lights that I am still trying to figure out... Getting this car running is like playing Wack-A-Mole...

Thanks everyone!
Rob