I recently noticed that my headlights would brighten slightly when I revved up from idle. I put a multimeter on it and found
13.6V at idle
12.9V with lights, AC and heater blowers running
12.9V at the Optima Red top when the car is off.
While at idle again, out of nowhere, it went to 14.5 then 15 then 16V for a split second and returned to 13.6 and stayed there.
I drove home and have seen no variance of brightness in headlights (with or without other accessories).
So, is this an alternator, VR, or both? If VR, can I replace just the VR (I think it is internal on my `87)