Pontiac Repair: Alternator Not Charging Battery, pontiac grand prix, bright test

Question
QUESTION: I have a 1990 Pontiac Grand Prix LE, 3.1 Ltr V6 FI.  The car last week on the way to work died and wouldn't restart.  One of our company mechanics pulled the battery and checked it.  It checked out fine.  So they thought that the alternator was bad.  So we purchased a rebuilt alt %26 replaced the old one.  And it doesn't charge.  He checked the ground and that seems to be fine too.  He also thought that maybe we got a bad alt.  So he got another one, switched it out and got the same results.  He had both alts checked and they are both good.  So he reinstalled one of the newer alts and told me that I would have to put it on a charger when i'm not driving it until I can find someone that can or will fix it the problem.  (He is unwilling to follow the wiring to find out where the problem is.)  Do you have any ideas as how to fix this?

Thank you for your help.


Matt

ANSWER: Hi matt:

this alternator needs 1 power on the big red wire on the back that is connected to a fuseable like at the starter motor. and the smapp plug should have 2 power feeds and possibly a 3'rd wire if it has an battery gauge on the dash. with the engine running one of the 2 wires should have a bright test light bulb and the second wire should have a dim lamp with the engine running if you have all of them the alternator should work if not have an open wire/blown fuse or blown fuseable link at the starter. good luck :)


---------- FOLLOW-UP ----------

QUESTION: I guess he checked those but we don't have a wiring schematic to know what wires go where.  He said otherwise he would be looking all over the motor and not knowing where each wire leads to.  Do you happen to have one that you might e-mail me?


Thanks again,
Matt

Answer
No, I'm sorry. My online service info from GM only goes back to 1998 so I have no access to older ones either I work at a buick store now anf they just aquired Pontiac a year before they cancelled the brand so I don't have any old hard cover service manuals to look in either.. Look at a auto parts store for a manual "chilton" or "motor" steer away from Haynes books. Your local Library may even have a book as well. Soory I'm not much help on this old of a car for you :(
Good luck :)