I think that is a good area to explore, but I did have rapidly blinking net indicator lights in the front and the rear VMMs. Also had input lights at the rear VMM indicating that it was communicating with the front. I had input 17 light go on (rear VMM) when the ignition key was turned to start, although it was rapidly flashing indicting a short.
I think the rear VMM controls the rear lights through its output section. I had no lights in the rear of the coach. Also, I did not have input lights on the rear VMM when I turned on the emergency flashers, which would support the net failure scenario. So is the problem with the front VMM (failure to communicate) or the rear VMM (failure to execute), that is the question. My coach is a not equipped with a HydroMax unit.
I have ordered the replacement from JCA which should ship later next week. Then I should have 2 good units to work with.
Thanks for your help.
2004 Alpine Coach 38FDTS