72,
Not everyone here knows what a 154 fault is other than its brake related and it shuts down the unit.
So with not much info to go on, here are my thoughts;
1) Drive initiates and the brake picks too late causing rollback. Parameter check.
2) Drive initiates and brake switch doesn’t send correct signal that it’s indeed lifted. Check switch contacts.
3) Brake drags and comparator signals are beyond parameter tolerance. Clean and adjust brake components.
4) Sluggish brake pick similar to #3
5) Brake coil open. No brake picks at all. Check coil resistance.
6) Broken signal or bad contacts on brake relay. Check.
7) Low voltage on brake pick or hold if that’s part of the circuit. Check.
8) Faulty/loose brake switch hardware. Inspect.
Hopefully one of these common situations gets you out of the weeds and in the right direction.
