Brain fart regulator question Options

[mb911]

So was noticing I have less voltage while the car is running. I am use to seeing 13/14 volts as the pretty much normal. I have a fairly new marchel alternator and this year I am seeing 13v on the high side. Now I do have more electrical items, wide band o2, mega squirt, and active exhaust. Regulator going bad? Pictured in upper left. Hmm maybe I have them on the wrong pins? Might have messed that up?

[mb911]

So verified some basic connections and ohms tested the wiring. The 12v wire all good. Ground good. dF is weird as I get different values depending on what 12 pin connection I check. I know that’s not a field test but now concerned I could blow something out with over voltage

[Spoke]

dF is weird as I get different values depending on what 12 pin connection I check.

What does the 12 pin connection have to do with DF? In the 914/4, DF goes between the alternator and the VR and goes through the 3 pin connector between them. That's it.

Did you do some tests on the 3 VR voltages while running? This can tell a lot about your system.

When running, measure these voltages at the VR:

D+ should be 13-14V
DF should vary between 5-10V depending on electrical load.
D- should be 0V

Also measure the battery voltage:
B+ should be 13-14V and follow D+

Measure all voltages with respect to a chassis lug, not the engine case.

For the field test, remove the VR and short DF to D+ then start the engine. This should force maximum voltage of about 16V on D+ and B+. Do this for a short burst as it's hard on the battery and alternator.

As an aside, my '86 930 was showing low battery voltage (12V) and slow starting. I bought a new battery and immediately got 13.5V steady. You mentioned you were going to replace your 10 year old battery. Did you replace it and did it make a difference?