Gen Light won't turn off
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
The GEN light is controlled by the sense wire (on the 2 wire plug, 1 is hot all the time and the sense wire is hot with the key on). If the diode trio has a bad diode the light will stay on or glow.
If you're up to ripping the alternator apart, it's easy to test with a multimeter.
Same with the rectifier:
With the rectifier out, gently lift the brass tabs away from the posts. To test, use the multimeter and look for continuity in one direction across all the tabs. If you clip the black lead to the fins, 3 tabs will have continuity 1 way and the other 3 will show open. Reverse the meter leads, and the 3 open ones will now show continuity and the first 3 will show closed.
I forgot- the very FIRST thing that you should check- make sure the 2 wire plug is good. Lots of alternator problems are caused by a broken wire at the alternator plug!!
Rebuilding a SI alternator is no trick. Mark the case halves, 4 bolts and it comes apart, Changing bearings, brushes, diodes even the stator and rotor is easy. It's still cheaper to go get a reman, but
If you're up to ripping the alternator apart, it's easy to test with a multimeter.
Same with the rectifier:
With the rectifier out, gently lift the brass tabs away from the posts. To test, use the multimeter and look for continuity in one direction across all the tabs. If you clip the black lead to the fins, 3 tabs will have continuity 1 way and the other 3 will show open. Reverse the meter leads, and the 3 open ones will now show continuity and the first 3 will show closed.
I forgot- the very FIRST thing that you should check- make sure the 2 wire plug is good. Lots of alternator problems are caused by a broken wire at the alternator plug!!
Rebuilding a SI alternator is no trick. Mark the case halves, 4 bolts and it comes apart, Changing bearings, brushes, diodes even the stator and rotor is easy. It's still cheaper to go get a reman, but
Last edited by TimAT; Jan 27, 2007 at 09:23 PM.
