My old alternator on my 88 Iroc Camaro went bad pretty much all of the sudden. I had the old alternator tested and it did not pass. I replaced with a new alternator (had that tested too and it passed) and still having same problem - it's not charging the battery. I checked all the fuses, everything looks good. I cleaned all of the grounds and connectors, that looks good as well. I also, checked all connections to the starter and it all looks nice and tight.. Voltage was checked from the pigtail in the back of the alternator and it was good. The red wire was 12 volts constant, brown/white was also 12 volt constant with ignition on.

Please help!!
Thank you!

 

Means nothing ;
all you are seeing is the battery voltage there if engine not running and Alt not charging.

Output from Alt should be above 12V with engine running.
With a low battery should be seeing 13.5 or higher volts at the Alt terminal
A DVM on the battery Pos terminal should also see volts change ( over 12V ) if Alt is charging correctly

 

Thank you for your respond. I did find a break in the wire from the alternator to the battery. After replacing the wire its running great! Thank you again for your input!!