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?

[Spoke]

Try these measurements with engine running; lights on and lights off.

D+ to chassis ground. Should be 14V
D- to chassis ground. Should be 0V
DF to chassis ground. Should be 5-9V
Battery POS post to chassis ground. Should be 14V
Battery NEG post to chassis ground. Should be 0V

D+, D-, DF can be measured in the plug coming from the alternator. Measure to chassis, not engine case or tin.

When did this start happening? Did you do any work on the car?

[Gatornapper]

Spoke -

Ran tests tonight after 1 hour drive, so nominal battery voltage at time of test was 12.2 v, not my normal 12.6

Results of Lights Off in Blue; Lights ON in Red. All readings to chassis ground from VR pins.

So what does this tell you? Clearly something major is wrong as the DF voltages are no different from the D- voltages. But when D+ and DF were jumped, battery voltage was about 17v....

Bad relay board? No, do not have another....

TIA,

GN

Try these measurements with engine running; lights on and lights off.

D+ to chassis ground. Should be 14V 11.73v 10.89

D- to chassis ground. Should be 0V .015v -.004v

DF to chassis ground. Should be 5-9V .015v-.004v

Battery POS post to chassis ground. Should be 14V 12.2v
Battery NEG post to chassis ground. Should be 0V 0v

D+, D-, DF can be measured in the plug coming from the alternator. Measure to chassis, not engine case or tin.

[Spoke]

Spoke -

Ran tests tonight after 1 hour drive, so nominal battery voltage at time of test was 12.2 v, not my normal 12.6

Results of Lights Off in Blue; Lights ON in Red. All readings to chassis ground from VR pins.

So what does this tell you? Clearly something major is wrong as the DF voltages are no different from the D- voltages. But when D+ and DF were jumped, battery voltage was about 17v....

Bad relay board? No, do not have another....

TIA,

GN

Try these measurements with engine running; lights on and lights off.

D+ to chassis ground. Should be 14V 11.73v 10.89

D- to chassis ground. Should be 0V .015v -.004v

DF to chassis ground. Should be 5-9V .015v-.004v

Battery POS post to chassis ground. Should be 14V 12.2v
Battery NEG post to chassis ground. Should be 0V 0v

D+, D-, DF can be measured in the plug coming from the alternator. Measure to chassis, not engine case or tin.

I assume the GEN light is off? It looks like there is no activity from the VR. DF drives the alternator armature and with 0V on DF thus 0V on the armature, the alternator is technically off and not running. You might want to check the resistance from the VR pins to the alternator plug just to make sure DF connects to DF, D+ to D+, and D- to D-.

If the VR pins to alternator plug resistances are good (0 ohm), then I would suspect the VR.