The 2 devices on the 606 DBW IP are a sensor (rack position feedback) and an actuator (that moves the rack).

The ECU drives the rack actuator and uses the position sensor for feedback. The actuator signals are just a "drive the rack more" or "drive the rack less" type of thing.

Drive by wire cruise is just an extended function of the ECU. Instead of the ECU trying to modulate the fueling level given the pedal input, it modulates the fuel level to maintain a preset road speed. You'll notice in a properly functioning 210 that the pedal does not move in response to the cruise control calling for more fuel. Not like it does on a car where the pedal mechanism is actuated by the cruise control.

This also means that the cruise control on a 210 is rock solid. There is no mechanical slop from the external actuator or linkage like in a 123/124.

This all happens within the ECU and there is nothing that can be gleaned from the signals to the IP that will help you with external cruise control operation.

I think your best bet would be to send your 606 pump out for a rebuild and put it back to stock if you want your cruise to work.

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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