Late 2005 W211 E320 CDI Estate

I bought this car about six months ago, for months everything was ok, then it wouldn't start.

All the usual lights on the dash but just a faint click on turning the key. After a few attempts it starts and runs fine.

I changed the battery for one I know to be good. Worked fine for a couple of weeks, then same problem again, even after fully recharging the battery.

The F59 (I think) fuse has been upgraded to 20Amp and has continuity, though I tried another fuse just in case.


Checked it with an Icarsoft MV 2.0 diagnostic tool...


Engine off:

Voltage (DLC) 12.28 - 12.41 Average 12.33


Engine on - No load:

Voltage (DLC) 8.46 - 12.41 Average 11.92 (same reading with a multi-meter on the jump start posts in the engine bay).

Revving engine doesn't change this.


Engine on - Headlights and Heater/Aircon on: Average 11.88


Can I assume the voltage regulator on the alternator is dying?