[T3] Odd Electrical Gremlin - Voltage Regulator?

[Robert Bills]

I'm having one heck of a time tracing this down.  Some ideas would be helpful.





A few weeks ago the following started on cold starts:  Gen light would glow dimly at idle, then get progressively brighter up to about 2500 rpm or so (guessing as no tach), then go out and stay out.  Generator belt is good.  Voltmeter tests showed nothing unusual, although regulated voltage was a bit lower than when the VR was new.  Also, my fuel mileage has gone down a few mpg.  My suspicion has been that my VR is on its last legs (not a Bosch - an american made generic acquired in 4/11 from Autozone because my local suppliers were out of the Bosch and I needed to get to a VW rally).  I've been told that these generics often fail after 8-10 months.  I had planned to order a Bosch unit in February, which is scheduled tune up time.





Last night, on a cold start after sitting about 3 hours, the gen light didn't glow after start as it has been doing the past few weeks, but after shutting off the motor after about 20 minutes on the Interstate, the gen light came on brightly and stayed on.  It didn't matter whether the key was in or out of the ignition, and oddly, when I turned on the 4-way flashers (I was turning everything on and off to see what, if anything, might affect the gen light staying on), the oil and gen lights started flashing in addition to the turn signal indicator lights.  When I started the engine the gen light went off, and when I tried the 4-way flasher with the engine running, only the turn signal indicater lights flashed (as they should.)  The gen light stayed on again after I shut off the engine, and was on for at least an hour (gave up and went to bed).  The gen light was off this morning, the car started normally (no glowing gen light this time), and when I shut the car off after about 20 minutes of driving the gen light did not glow as it had last night.  Voltmeter test of the regulated voltage was the same as last week - 13.7





I am at a total loss as to how to trace this issue.  Any suggestions?
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