Hi Richard
That's interesting thanks.
I can find no mention in the VDO CANcockpit manual about terminating resistors fitted across either of the two CAN bus's in the master gauge but it may be configurable. Easy to check though by removing the master gauge 26 pin connector whilst monitoring the resistance across the CAN bus pins at the diag socket to see if it increases to about 120 ohm.
Rog mentioned in his comment on this thread that the BCU pins can get mucky or corroded. My thought was that if on this vehicle the BCU is one of the units with a terminating resistor, bad pin connection might lead to a bus term missing or high value and hence as you say due to reflections data corruption to the instruments.
Regards Tony
