I also had an issue where my ignition switch would not shut down my engine, C-13 CAT though, not Cummins. I replaced ignition switch and start relay in front run box, and still not shutting down. Mine would shut off id I hit my emergency stop button on HWH 2000 series leveling pad, then get out and hit HWH reset button in outside front run box to get dash to shut down. Ended up being 2 diodes in the HWH main control box in my basement compartment, I sent it up to HWH to be rebuilt.