1990 351W Charging problem
Thread Starter
|
New User
Joined: Oct 2006
Posts: 8
Likes: 0
1990 351W Charging problem
I have had the alternator tested twice and both times was told it was fine, yet when I turn on the lights and defroster at idle my gauge goes to very low discharge. Also the lights dim until I give it a little gas. The belt is in range. New battery. My idle is at 650 rpms. I would appreciate any ideas you have on how to fix this problem.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Could be a bad ground cable on the truck.....
But check the charge voltage with a multimeter with the engine running. It should be a pretty steady 13.5-14v. If it varies widely with rpm then the regulator is gone. Both the regulator and rectifier are internal to the alternator.
I also have had alternators with bad rectifiers/regulators test OK on the local garage bench testers.
But check the charge voltage with a multimeter with the engine running. It should be a pretty steady 13.5-14v. If it varies widely with rpm then the regulator is gone. Both the regulator and rectifier are internal to the alternator.
I also have had alternators with bad rectifiers/regulators test OK on the local garage bench testers.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
It should stay at a steady voltage... that's what the regulator does. You are getting a large voltage drop somehwere, I'd suggest you check/replace all the grounds on the motor, and clean all battery and alternator connections. Test the DC resistance between the battery and frame ground(motor off). It should be 0 ohms.
