What chassis is your coach?
If Workhorse, they used Waco and Meritor depending on chassis model so important to note.
Had ABS issues with our W22 chassis which after a few months figured out it was Meritor after downloading all the Waboc info. Took it to Navistar for the brake recall, they scanned the ABS for issues, said it was the front left sensor and Master Cylinder.
I drove it for a year and finally got around to replacing the front left sensor. ABS light went off driving out my 60 foot long driveway.
Master Cylinder issue is the crappy Master Cylinder design for monitoring front and back brake pressure. Requires replacement of the MC - or, just unplug the sensor under the reservoir., problem solved.
Some may say phewy to that and hope I’m never behind them needing to stop. Well, I know my coach and I keep it properly serviced. And my toad has a brake system. It might not can stop my coach, but I mechanically inclined enough to know when there is an issue.
91 Ultrastar Champion02 Georgie Boy Landau 8.1l Workhorse
03 Jeep Wrangler TJ 2018 Jeep Wrangler JK toad