" can" , also faults 43 & 44 are displayed when the communication lines have an issue. Could be shorted or open can wires, can wiring shorted to batt positive, or a bad display or controller. You'll need to test the can wires ( starting @ the controller - CA401 pins 3 & 4, follow thru CA501 pins 3 & 4, thru TB301 pins 3 & 4 which is the control cable connection, up to CA101 pins 5 & 6, to the display - CA701 pins 5 & 6. If the wiring tests ok, your looking at either the display or the controller.

Curtis has a lot of stuff on their website, have you tried there? curtisinstruments (I think)
you might add your e-mail to your profile, it won't show here, for good reasons.

found CAN Fault hooked up Curtis hand set. don't know what it means, dont have manual

I swapped then out from and still the same problem

batteries are (naturally) the first thing to check.
are they all good and well charged and stand up to load testing?

I have the same issue with my wav50 did you have any luck with yours

I agree with crownie, aside from any of the panel switches or platform ED switch/connections, check the plugs in the back of the service panel. They habitually come apart. Just use a wire tie to secure is so. Also the fuse holder in the service panel is a common problem.

check all your service panel switches and ED switches are in correct positions
acts like drive/push switch is open circuit, could be plug connector to service panel