1993 240, power windows stopped working all switches/all windows.
Also, shift lock now requires override.
Any suggestions?

 

Check all the fuses good and make sure the connections on teh fuse box are good.They are known to corrode.

 

most probable cause would be the 12 volt power on the window switches. it's also a good idea if you look on the main switch. or maybe a window regulator replacement should be done.

 

My mother has a used (no manual included) 1992 240 that has the exact same problem that you described with the windows not responding (at all) to the switches and the shift lock requiring override. Were you able to solve your problem? I'm new to this forum (and to car repair) so thanks so much for any help you can provide. Be well!