gt40 wrote:

The canbus is not fused as such so pulling a fuse that removes power from a module wont necessarily affect the canbus or how it communicates.

Ideally one needs to disconnect any electrical connector from a module to isolate it completely from the bus.

But before doing all that you should test the canbus using a simple multimeter via the diagnostic plug. Its very quick and easy and will at least point one in the right direction.

Your right
Pulling fuses and relays will not help at all if a module has gone down / shorted somewhere.
In fact it is probably best to check resistance with the battery disconnected and allow some time for everything to drain out (or hard reset with the battery leads), then test.