easiest check
The easiest check is to check for shorts as you build.
As you build up each connector:
1) ohm check from canbus high to canbus low and make sure it is open.
2) ohm check from canbus high to connector back shell (ground) and make sure it is open
3) ohm check from canbus low to connector back shell and make sure it is open.
4) check from the newest connector that you just got done building up to the previous one for continuity from canbus high to canbus high, and from canbus low to canbus low.
5) when you are all done, check from the last connector to the first connector continuity from canbus low to canbus low; and canbus high to can bus high, and open from canbus high to ground and canbus low to ground.
Do these checks before pulling the connectors into the boxes and before power up everything.