Although the original wireless design of the Xpress plow with E-88 got a big black eye, they are really quite trouble free.

Common (I use the term loosely) problems:

Angling - C Valve, broken O Ring on the Dual Pilot Operated Check Valve.

Plow won't stay up - This is important, if it ONLY won't stay up when you try to angle it, inspect the B Check Valve. The ONLY part of the E-88 that was changed to make it an E-68 was the B Check Valve. The original design had an O Ring that would break, causing the drop when angling problem. IF you pull the B Check Valve and find a broken O Ring, replace the B Check Valve. The new one will use a ball instead of a poppet and O ring.

Controller won't turn on, but it is getting power. Check the GROUND. The main 22691 Universal Harness has numerous splices in the ground circuit that can break over time (they have, it is pretty common). Also, check the plug in the cab, and make sure all the pins are in the plastic plug housing. They have been known to push out and cause intermittent problems, or functions not to work. The ground is black with a white stripe. IF the controller lost its ground, you can replace the complete 22691 harness with the new 22691S, OR you can cut the black with white stripe wire close to the loom and leave enough to splice a new ground wire to it, and ground it under the dash. Been there done that.

Keep in mind that the self diagnostics of the controller only checks continuity and load. It does not know if a Valve is bad, O Ring broken, etc. It is electrical only that it looks for, nothing mechanical. IF the red Monitor light is not blinking, everything is fine electrically. Note it does not know if the Motor is good or bad.