Hi Erik,

Be careful using Reed relays. They're very sensitive on electromagnetic fields.
As in the bus you may have some high level fields due for example to electromagnetic retarder, it could open or close the relay.

Reeds are sometimes used to detect fields...

We have experienced it a few days ago again on a device designed by my compagny. This is a current inverter to reverse the polarity of a given current, using a H bridge. This is used for current sensors test in lab.
When applying only 300A in the main loop (the current to measure), the electromagnetic field associated makes the reed relay to open and it's located at 20cm.

For your termination problem, I have seen a manufacturer using FETs for termination switching on CAN bus. I hadn't anaylsed this, but it could be a way to investigate.

In a recent past I've worked for Renault trucks (Vovlo trucks now!) and IRISBUS was a bus manufacturer depending on Renault Trucks. Now it's part of FIAT.
I've spent a while on the whole electronic inter-system architecture and also on a specific ECU.

What are you designing ?

Regards
Stephane