Alternator question., Not Charging. Options

[Olympic 914]

Took the car out for a drive today, planning on going to dinner. everything is working as it should. getting on the PA turnpike and I had to accelerate briskly to get into traffic, and a moment later I noticed that the RED alternator light had come on. Pulled of at a wide spot to check the belt and wires and shut it off. Not checking the belt with it running. Belt good, plug tight, tapped the VR a couple times for good measure and started it back up. Light still on and now my Autometer AFR gauge just had bars. I know that is because it doesn't turn on until the voltage is +13v So not charging.

Now I am on a limited access highway with the next exit `12-15 miles away. Good thing had the battery fully charged on the tender before I left the house. So I made it to the next exit, turned around and headed back home for a total of 35 miles on battery only. Whew. But that shot dinner.....



Replace the VR with another I had that previously tested good. still no charging. checked the plug on the relay plate again. looks good.

I have not yet checked the wire connections at the alternator, possibly a wire vibrated loose during the brisk acceleration.

Now the question

I read to test the VR to short between D+ and DF and if the alternator is good voltage at the battery will go to alternator maximum of about 15-16V

So do I REMOVE the VR for this test? and jump between the D+ and DF at the relay plate.
OR
Leave the VR in place and short between those pins?

[Gatornapper]

Ok, friends - this thread has been very helpful, but my situation is a bit different from any listed here.

New gel battery, resting voltage, 12.6. Ground connections good.

Gen Light:

* Comes on very bright as it should with ignition on, engine not running.
* Completely goes out when engine is running. No, it's not even dim.
* Comes on dim when headlights are on.
* MAXIMUM charging voltage with engine running, no loads except ignition, is 12.2, very slowly drops over time; drops to 11.9 with headlights on, slowly continues to drop over time. Strong battery lets me drive for 30 min with headlights on.
* Gen light never comes on bright when engine is running; only when engine is off.

So, alternator is not charging - OR, VR is not adjusting voltage for load.

DID THE D+ TO DF Jumper TEST: at rpm, voltage at battery jumps to 16.9 to over 17.

So alternator is good, right?

Purchased NOS regulator from great fellow member here.

My original VR and the NOS VR both perform exactly the same....no charging. Gen light is OFF unless I turn headlights on, then is dim. Engine running with either VR is 12.2, and seems to stay there for some time.

So it seems to me that there is some charging going on - just not enough.

Been doing auto electrics for almost 50 years and never seen this one. Never seen a VR/alternator problem before I couldn't diagnose and repair.

Oh - would the wrong size Gen lamp cause this? Seems the correct size to my by the way it is functioning......but hey, what do I know?

Oh- ordered a cheap new VR from Rock Auto to use as a test unit, but it won't be here for 10 days - like to have the car ready for the local 9/14 - 914 event.

TIA,

GN