Electrical problem with ’87 300SDL

[cgryphon]

This car has been at my Mom’s house for the last few years. It gets driven about 300 miles per month.

Last time I was there, I had to charge the battery to start it up. Radio is dead, not just “_ _ _ _” but blank. Everything else works fine, windows, seats, sunroof, dash and lights, etc.

Driving down the highway, suddenly all electrics go dead…….gauges, lights, everything. Car keeps running fine. After 5 seconds it all powers back up again, like nothing happened. Happens again on the off ramp, and twice more getting back to the house.

Checked all the fuses in the box, wiggled all the wires and cables, including around the battery, alternator, starter, etc. and could find nothing amiss. Went out for another ride up and down the street and it did it all again, 4 times in around 10 minutes of driving. Weird.

Any thoughts of what to check? I’ll be there over the weekend. Car keeps running fine, just zero electrical.

Thanks and Happy New Year!

Clay