Onan Service Error 45

So which is it - does it not run, or it runs and won't provide power? On an Onan 5500 generator, error code 45 indicates a "Speed Sense Fault," which usually means there's a problem with the generator's ability to accurately detect its rotational speed, potentially caused by issues with the generator windings, wire connections, slip ring corrosion, or excessive load on the generator itself. So, it could be lots of things. Have you tried running it without a load? Is the breaker tripped on the genset itself? Fuse blown? Seems odd that it ran fine and then it won't while moving. Makes me think of a loose wire.