Combination switch on a 210 works with the EIS (ignition key) switch.

When you select the various modes it switches resistors onto control lines. The EIS reads these resistances and generates the CAN bus messages to the various controllers.

Wipers, horn -> front SAM
turn signals, flash the brights -> headlight switch
Cruise -> hard wired to the ECU

The 140 was the first car with CAN bus. 210 was the first mainstream car with it and they were still tinkering with the best ways to do things. By the 211 time they had a 'steering wheel control' module that integrated everything on the column and put it on the CAN bus directly.

If you have access to a Xentry you can get into the system through the 38 pin plug and see what requests from the combination switch are being received by the EIS when you move the combination switch.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech