Yes, in fact my luck is the same as Richard's. It has the MAS box, not the Klima relay. I read up on the Klima Relay. Does the MAS box have the same type of solder failures?

I checked the belt tension - no problem, and the belt is fairly new.

I disconnected / reconnected the battery. No change. While I saw from other posts that a tachometer malfunction is often also related with a Klima relay, I don't know if it is controlled by the MAS in my car. If it helps, my tach is operating properly, as is everything else on the car.

Next steps? Troubleshoot the MAS? Jump across the high pressure switch?

Thanks in advance!

__________________
D.H.

04 ML500
02 E430

Experience is something you don't get until just after you need it.