Flaky ignition on aerocab trucks

To my knowledge this is a fact of life with these trucks so I've just lived with it, but I'm fed up now and wanna figure it out. What I'm talking about is on W900s, T660s, and I imagine T600s and T800s. The problem being where you go to start the engine and nothing happens, you keep turning the key back and forth, one time it might turn over a tiny bit and stop, the next it does absolutely nothing, and after a few or several tries it starts perfectly. But most of the time it works just fine on the first try, it never leaves me unable to start it either. I just started doing some digging online and I'm hardly finding anything, although I did see something about a starter interrupt relay, is that the likely cause? That would make sense as I don't hear the solenoid click when it doesn't turn over. Have any of y'all experienced and solved this?

To clarify, this is on a 2019 W9 glider with a 3406E, but I've experienced it on other W9s as well as T660s.

 

I appreciate the input, although I'm familiar with that sort of issue and the remedies, hammer included. I've driven KWs with this issue ongoing over hundreds of thousands of miles in each truck. Never have I found it to relate to a starter, or more specifically a starter solenoid. E.g. the W9 I drive now, it's at 434k, ~350k of which I've done and it's had that issue since I got in it. Same deal with the W9 I was driving before I switched from 3 to 4 axles, and so on and so forth.

Years ago when I was green and first encountered this, I asked people who had been around the block about it and they said it's just a KW thing. I've brought it up to other people over the years and gotten the same answer, although some people assume it's the ignition switch, but they've never bothered to try fixing it.

 

There we go, I knew someone else here must have experienced this lol. So it is the interrupt circuit after all, sweet. You ran the wire from the start position on the ignition switch to the solenoid's control signal input? I'll look at the wiring and see if I can figure out how the interrupt circuit works. Hopefully there's a direct way to bypass it, maybe just a jumper in place of a relay in the fuse box. If not, I've got your solution in my back pocket, thank you. I'll let you know if I come up with a more direct solution.