How to Troubleshoot a 2016 Kawasaki Mule Pro DXT Diesel Engine That Won't Turn Over?

It sounds like you're dealing with a few potential issues. First, the fuel pump relay is crucial because it powers both the fuel pump and the injection pump solenoids. If you can't find the voltage regulator, it’s typically located on the right side of the machine, near the alternator. In diesel models, the setup can be a bit different, so it’s understandable if it’s not where you expect. Since you mentioned that the engine doesn’t crank at all when you turn the key, but you can get it to work by shorting across the solenoid, that suggests the problem might be with the ignition switch or the relay. If the battery voltage is good—over 12.5 volts—then it’s less likely to be a battery issue. However, trying a different battery could still be worth it, just to rule it out completely. You also asked about the modules under the front hood. These can sometimes cause issues, but since you've checked all the wiring harnesses and fuses, it seems like you've done a thorough job there. The neutral switch is typically located on the transmission, and if it’s malfunctioning, it could prevent the engine from cranking. If you have access to a wiring schematic, that could really help you pinpoint where you might have lost power or connection. Given that the alternator seems to have an internal regulator, it’s possible that the issue lies somewhere in the electrical system. Once you run wires from the battery to the fuel pump and injection pump solenoid, you should be able to see if those components are functioning properly. Keep me posted on what you find!