I Have a '85 300D with the following symptoms:
While driving, battery light came on and subsequently noticed that pwr windows, tach, gas gauge, temp gauge, blinkers, rear def, sunroof, etc. stopped working. I recently had a new rear window installed but have used the new defroster 5-10 times previously with no problem. Lights, starter and charging system appear to be working fine. Seems I blew some sort of fuse or relay that controls all non-essential equip. All the fuses on the firewall checked good. Any cure-all that may be a simple fix? My mechanic is swamped through the weekend so I may take a shot at it myself. Thanks for any help.

CIRCUIT 15X HAS FAILED.
THIS CIRCUIT STARTS AT IGNITION SWITCH (LABLED 15X) THROUGH 2.5MM RED WIRE WITH YELLOW TRACER TO FUSEBOX.
TEST THE WIRE FOR POWER FIRST WITH KEY ON,IF NO POWER TEST AT THE IGNITION SWITCH.
MF

PS, turn the ignition switch back about 2mm after starting and see if this helps. IF so, your switch is faulty and will have to be replaced. If not, check all of the fuses for hair line cracks.

__________________
Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

Thank you Mike and Benzmac, I will investigate!

Clay