I could not connect to my ABS computer either; I used the green cable and tried to connect to it using both a bluetooth dongle and an ODB2 USB cable with both a Win7 computer using Multiecuscan and an Android tablet using AlfaBB. Neither could connect to the ABS computer, but the Android using bluetooth ELM dongle (and no other cable) connects OK to the engine ECU. So I took it to an Alfa technician and his scanner could not connect to it either, furthermore the engine ECU would not even show up on his scanner. We even tried logging in as a 3.0 166 and still didnt show up. We were about to give up when he suggested trying an old Garmin scanner he had there and this was able to communicate with the ABS ECU and indicated a problem with the rear left sensor. Am waiting on a replacement sensor.
But I am a little mystified. I tried all different settings on the Windows computer and it seemed to communicate with it on the KLL setting but still wouldnt connect using Multiecuscan. I even tried disconnecting the plug on the immobiliser. This made no difference. My thinking is there is a bad contact/earth somewhere. Three computers couldnt read it but the old Garmin one did.