Looking for confirmation - fault Voltage Regulator?

[D_Ryan]

Good Afternoon All;

Headed out to work the other day in 'Frau Blue-car', my '85 300TD. Noticed that the charge light on the dash was faintly glowing, but extinguished one the revs came up. Aftera few short minutes it was glowing once again, albeit faintly, then it went out once more. Again out on the highway it made itself know. I turned around, parked the car and took an another vehicle.

Troubleshooting now, and with the engine warm and at idle, with high beams on and defroster/blower on high, the output measured at the battery is about 12.4. Increasing the revs shows a reading of 13.4 - 13.5. Turn the lights and heater/blower off, and the voltage at the battery climbs back to 13.4 - 13.5.

I'm thinking failing voltage regulator, but am looking for confirmation.

Thanks in advance,
Dave