QUOTE(yeahmag @ May 5 2022, 07:34 PM)
I just did the test on the D+ side of the light (blue wire) and it goes to 5V. It doesn’t go high…
When does it go to 5V? It should be at battery voltage so there is no current through the GEN light.
Did you check the voltages of the VR and battery?
D- to chassis
D+ to chassis
DF to chassis
Battery voltage to chassis
Do these tests with headlights on at idle and 3500RPM.
If D+ is equal to the battery voltage at low RPM then drops with high RPM, it might indicate some sort of rotational issue.
Not on a 914 but I had a car where the alternator would charge at idle then virtually stop working at higher RPMs. Removed the alternator and checked the resistance across the brushes and armature. Got a resistance value then when I spun the rotor, the resistance went way up. Took the alternator apart and cleaned the brushes and commutation ring and the alternator worked perfectly after that.