Check the solenoid for the main cab power. It's a relay down at the bottom of the fuse panel. Looks like it could be mounted on inside the fender of an old ford pickup. My 7220 gave me similar problems, and it was that.
Yep are 7140 did it also got a new one at dealer was fixed for short time rumor was case got a batch of em. Ended up getting one from our electric motor repair shop I believe if memory serves correct it's a 100 amp continuos duty. And been fine ever since