SB,
My lit shows Can serial data line on 104.032 HFM , obd1

The Can element at HFM module calls for 115-125 ohm test reading at module.
I believe this is OBD1 serial data link between modules vs. the later CAN OBD2 systems. [96 up]
Any which way, my lit shows code 42 as Can communication fault between EA,DM, and HFM somewhere..[ HHT tester chart does seperate these down to sub codes as to which module is bringing the code up]It also give the test teminal on each module for the spec ohmage of each..

???????