Further info:

Can serial data exchange on 124.032 HFM schematic does show the CAN link connector [X63/1] from therminals L/H on the ECU
N-3/4.
According to the info , this data link is simply a 2 wire parallel interface cable allowing data transfer/communication between the modules [ N4/1, N59, N3/4 and N4/3]
This is early CAN networking for OBD1 .
If you are having a CAN code 42, you may want to look at this X63/1 connector for a good connection.