OK
After you verify Single Flash on Ea/CC module, there are a couple of other test you may be able to do as I see you have some equipment.
We need a V reading on both sides of fuse #6
That will be power inputs to N4/1 -EA Control Module.
On the ASR control module, [N30/1 ] as in earlier posting, we need feed
from OVP to pin#1. I do not suspect that feed b/c you do not dispaly ABS lamp...Do you have ABS lamp when key is On, engine Off ?
Throttle position input/output are pins 34/31, respectively , on N4/1.
Might want to check there.
On N30/1 , they would be 13 and 16.
I would also check for closed CTP sw at idle ..That would bring on ASR w/o ABS lamp b/c that is direct Actualtor feed from Fuse 6.
Here is EA/CC ASR codes for pin 14
http://www.peachparts.com/shopforum/showthread.php?t=107630
I will also say that you are correct that the US never had that .031 chassis, but I hardly think that the ASR system in your car is any different or special than the standard ones in our USA chassis 124.051. They may be the same engine [ presumimg you have an engine typo ] and should be just first generation EA systems, so I highly doubt that my .051 info and schematics are any different.. they may be , but that would certainly surprise me.
This would be the 124 Coupe/124.051 with the 104.980/24 valve engine /1990 thru 1992/US
If you are correct on your engine #, void the above info....
Further research does show the Barbus engine, but I know nothing about these .
I have info for 104 engines # built for US market, so yours is a Euro thing, as I see that Brabus site list it as you do......ie.-104.890.
I do not even know if that is something added to a .031 or is a factory car ??[ pretty nice one , too]
If that is the case , we are incorrect on the assumption of a 890/980 possible typo..
If that is the case, I would surely have no info or experience on that chassis.