Control boxes
I have replaced both control boxes on my the 2 of my M-812 trucks. Memphis Equipment has them from Southern Electrical for $320.00 each. Main condition was that the internal sylimolds were not hitting in and staying very well. Resulting in you continuely flipping the switch to engage the sylinoids and then when you hit the starter, they would kick out or resulting in lower voltage to the starter.
I am experienceing lighting problems on one truck. I was hopeing that replaceing the control would solve the problem, but no such luck. Starter engagement and a stronger voltage are a lot better with a new box.
As stated, you can break into them and rebuilt the box, but it looks like a lot of work. BOYCE Equipment says they know how to wire around the box. Tom @ Snake River