That fuse description on S2central did not match my '94 S2. But did finally found a blown fuse which was correct. After changing it, the idle solenoid went to full open with RPM up to 4000.
Then measured resistance on the pin that goes to vems to ~20Ω with ignition on. With ignition off it's close to 0Ω.
Next step was changing the INJGROUP channel that drives the solenoid to the channel that drives boost valve.
Did not connect the solenoid here, but a measurement of resistance gave exactly the same values as with the previous channel. This readings are also not affected by changing the IAC lock to full open/closed.
So.. What has blown here? Any ideas anybody? Is it the driver or something else blown inside of the vems box?
For any case measured Ω with the econoseal disconnected, it was all ok, no leakage in the wire itself so the harness seems to be OK.