Some weeks ago, I posted in an effort to fix my Distronic (DTR). I was having very frequent dropouts of my Cruise Control more or less rendering it useless and it had deteriorated over time. It seemed that almost anything or even nothing would disengage the system. I'd get a beep and a DTR message, and I'd have to wait a minute to reengage it. And I really like to use cruise in many settings. I was guessing the problem had to do with a mis aligned Radar (the sensor behind the grill). No one was able to help me. I played to re-aiming the Radar sensor to no effect.

Last weekend I spent about 8 hours over 2 days using Chat GTP as my resource. Chat took me all around, sometimes in circles. I probably uploaded 30 screenshots of my STAR screens. But I finally saw an error code C1590 in the ESP module (Stability Control) that reflected a communication issue with the DTR module. Chat jumped on that one. It had previously mentioned in a number of those prior loops about deterioration (Corrosion) in various connector contacts. Chat told me to clean all of the connector contacts at both the Radar behind the grill and at the DTR module (located under the passenger footwell kick panel).

I found that the connector pins at the radar looked very good, but I cleaned them anyway. But at the DTR module, the pins appeared to have some corrosion. I cleaned those also. And "Problem Solved"!! It's now entirely desensitized. I also noted that the Radar connectors (2) are tightly sealed while those at the DTR were not sealed at all. Chat said, "MB's of this vintage are known to have connector contact deterioration". And in my case, I see many communication errors stored when I run a STAR Quick Test........none of these seem to affect anything. Chat also described how the DTR system kept an eye on all kinds of potential discrepancies and that even a very momentary comm error would cause it to disengage itself.

These Pins and Sockets are very small, so I'll describe how I cleanen them. I didn't have any contact cleaner, but I'd have likely used abrasives anyway. I used an Oxy Acetylene welding torch tip cleaner to get into the tiny sockets. It's essentially a set of mini round files in various sizes. For the pins, I taped a small strip of 320 grit wet/dry sandpaper to the end of an old ignition points file that was slim enough to get to all 4 sides of these small square pins.

One other observation was that the DTR module doesn't show up in the STAR Modules list (odd). The only way I could get at that module was via the quick test where I could select it and read it.
Hope this helps.

 

This topic is very interesting. I too have frequent cruise control drop outs but i do NOT have the distronic option. No codes present relating to cruise control.
Any and all suggestions to remedy this would be appreciated. Thanks