w124, 1994 Wagon w/Electrical Gremlins?
 

A cry out for help from a w124 addict! Crazy symptoms...total stall on highway a week ago during idling at stop light...battery totally dead, replaced old battery with new, checked alternator and is working within specs. Normal driving for one week and today same issue returned. Started the vehicle in below zero (-6f), allowed to idle for ten minutes, returned to vehicle and engine stalled with battery dead and unable to start. Clicking noise from relay box quite pronounced but I believe this to be normal. Any suggestions where to look now? Thanks, in advance, for taking the time to reply.

Most likely a problem with the voltage regulator.

You can try driving with a voltmeter connected. Radio Shack even offers one that will plug into the cigar lighter.

thanks, MB DOC, is this a big job or small, expensive part or not?

I replaced the VR in my wife's '95 wagon about a year ago, ~200K miles. I bought the part locally for around $40 and it took me about an hour to install. You should be able to find it cheaper online.

Have you verified that the battery is actually dead? It seems strange that a near-death battery could start a car in very cold weather, allow the car to run for some minutes, and then suddenly die. My guess is a bad connection somewhere. Suggest loosening, cleaning, and retightening all connections to/from the battery, same for all the grounds on the strut tower, etc.

Rgds,
Chris W.
3 x W124