Trailer ABS cycle not working.

I'd see what a truck mechanic has to say about that. I drove an 08 Columbia for a while and the trailer ABS light cycled correctly on it.

I took my Cascadia to a TA thinking the problem was going to be with the trailer. The mechanic checked the pigtail, saw that the power was not shutting off with the key, and went straight for that relay box. I gather it's not an uncommon problem.

 

I have a '04 FL M2 chassis Rv with Neverending abs malfunctioning. So far about 5$k ...... Many abs wheel sensors, some calipers and recently new rotors. They can get the dash abs fault to stay off ok. But upon first panic Stop, usually fronts, will seize, smoke and quickly loose braking altogether! I suspect it's the modulator sticking, causing the brakes to seize. I'd sit by road for half hour and calipers would release, followed by dead abs system, dash abs glowing red of course. But at least I'd have brakes.