Alternator electrical problem [Archive] - GrandAmGT.com Forum

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angrysk8r
02-17-2009, 08:49 PM
Finally got around to having my transmission rebuilt and I dropped the new one in. Everything started and ran fine until the battery died. Started checking the alternator and found that the voltage between the positive red wire on the alternator and a ground source reads 0 volts...then checked the same wire between the positive on the fusebox and it reads 12 volts. I'm assuming this means that somewhere there is a short on the alternator wire that is grounding it somewhere.

Problem is I can't seem to find exactly where that red wire on the alternator goes to...it disappears into the wire harness somewhere. Anyone know where that wire goes or where I may have messed it up by chance?

edited:
also did some multimeter testing...
the + on the fusebox and a ground reads 12v (normal)
the + on the alternator and a ground reads 0v (should read 12v when not running)
the + on the alternator and the + on the fusebox reads 12v
the + on the alternator and the + on the starter reads 12v

another thing...it will start and drive for quite a while (did this when i first started it, not knowing a problem until the battery light came on), so i assume the battery is at least getting a partial charge somehow or it wouldn't have driven half as far
and when it's starting the starter sounds really slow, almost as if the battery is bad but i just replaced it with another one thinking that may have been the problem

Grandamgtblk99
02-17-2009, 09:40 PM
Starter I think, but im not sure.

angrysk8r
02-17-2009, 09:54 PM
Starter I think, but im not sure.

that's what i had assumed as well...but i just did some multimeter testing...
the + on the fusebox and a ground reads 12v (normal)
the + on the alternator and a ground reads 0v (should read 12v when not running)
the + on the alternator and the + on the fusebox reads 12v
the + on the alternator and the + on the starter reads 12v

if it did lead from the alternator to the starter wouldn't it not read 12v? assuming the short is causing the 12v reading...

another thing...it will start and drive for quite a while (did this when i first started it, not knowing a problem until the battery light came on), so i assume the battery is at least getting a partial charge somehow or it wouldn't have driven half as far
and when it's starting the starter sounds really slow, almost as if the battery is bad but i just replaced it with another one thinking that may have been the problem

Grandamgtblk99
02-17-2009, 10:05 PM
Im a little tired to understand what all that says. But Im pretty sure it should be sitting at 12v even when off.

You could run your own wire from the alternator positive to the battery itself and see if it acts any different.

Maybe check the wire that grounds the engine block to the chassis, to make sure the engine ground is good.

2000 GT Coupe
02-17-2009, 10:20 PM
I think the fact that the starter runs slow is an indication the voltage going to the starter is not there, check the starter lead.

angrysk8r
02-17-2009, 10:27 PM
recieved advice off of GAOC saying the fusible link may have blown somehow...going to test this tomorrow and see if it fixes the problem