Jacob's brake

Driving on a unpaved rough road rhis morning, Jacob's brake working fine, made it to pavement drove about 1mile let off pedal and my Jacob's brake wasn't working hasn't worked all day, my motor is a cat c12, and the wires coming from Jacob's brake switch are still running to block, how does it get its power through relay, circuit breaker, I kinda tested the switch on dash and I really don't know if there supposed to light up tester if not working but nothing lit up any help be appreciated thanks

 

I thought about that also and tried it still didn't work, even tried pulling up on clutch pedal

 

Nope, the one other thing is that it supposed to have a on and off switch, and another switch for low med and high, they removed the on and off switch awhile back so somehow they got power just going to the low med high switch and somehow bypassed med and jsut have low and high

 

The one thing is I have no on and off switch somehow bypassed it and all I have is off low and high on the one switch , traced those 3 wires and there all going into the block, so was thinking it has to have a power wire somewhere