42RH OD and LU testing

If it just stopped working all of a sudden it sounds like you lost power supply somewhere like a wire connection or maybe your vacuum line fell off the vacuum switch. If it’s like mine the higher vacuum keeps the circuit closed via the vacuum switch and the drop in vacuum due to increased load/pedal stomp/passing opens the circuit resulting in kick down. If you have a separate toggle type power switch on the supply side I’d be checking those connections too as well as anything with physical connections. Also the pressure switch ground.