'90 coupe low voltage

[bertsbassbox]

Hi guys. I have a '90 coupe and at idle the voltage shows 14.6, but when i turn the lights on then step on the brakes the lights dim a little and the voltage needle goes down a little. Then when I put the car in drive the volts drop to 10 or 11. I took it to advanced auto and they load tested the battery and it showed good and the alternator showed good too. I replaced the alternator with a brand new one a week ago because of the same problem but it didn't help. Any ideas on what might be the problem? Thanks for any help!

 

[gmjunkie]

Hi guys. I have a '90 coupe and at idle the voltage shows 14.6, but when i turn the lights on then step on the brakes the lights dim a little and the voltage needle goes down a little. Then when I put the car in drive the volts drop to 10 or 11. I took it to advanced auto and they load tested the battery and it showed good and the alternator showed good too. I replaced the alternator with a brand new one a week ago because of the same problem but it didn't help. Any ideas on what might be the problem? Thanks for any help!

Check and Clean "ALL" Grounds!! Ex-Specially From Battery to Chassis and Engine!!!!!

 

[G Winter]

If cleaning all the connections don't fix it. Then I would say you have a fried diode or even two in the alt. Unless your belt is slipping really badly, which isn't that likely with the serpentine belt .

Glenn


Junk, a blown fuse wouldn't allow any charge, would it ?

 

[gmjunkie]

If cleaning all the connections don't fix it. Then I would say you have a fried diode or even two in the alt. Unless your belt is slipping really badly, which isn't that likely with the serpentine belt .

Glenn


Junk, a blown fuse wouldn't allow any charge, would it ?

No,a fuse wouldn't do it!! But if someone has put a Larger pulley on the alternator to gain a couple HP,that might!!