My 2002 39x thinks an estop is on somewhere. I've replaced the 2 that had buttons broken and opened the other 2 and blew them out. The 3 leds in the box glow dimly. I'm thinking there may be a ground problem somewhere. How do I troubleshoot this?

Also, a prior owner wrote in the control box on truck, 1 8  and then 2 5 estop bypass. I have also read that you can jump j1 and j8 to bypass in an emergency. I can't seem to locate j1 or j8. Any ideas?

You are probably right, when you say you have a grounding issue. Chances are, the switches on the inside of the estop stations are bad. Check those first.if they are good, but some moistre inhibitor on it. This will keep the water out of the switch. Go to the estop at the water box, at this station the whole loop begins and ends. And then ohm out the individual wires, going to each station. This will tell you if there is an issue with the wiring. 

For your estop bypass, j1 and j8, as well as j2 and j5 are designations on a plug on the estop card. Temporary a paper clip gets you by, but it is never a good idea to bypass safety features. Repair them and maintain them.

Found a loose wire at an estop. Thanks for your comment.

I think I am the one that wrote that in the panel