Don't know if it will help anyone but a problem came up when installing the Cummins 4BTA diesel into my Town Wagon. Everything was wired correctly and extra good grounds but the starter would barely turn over, not enough to fire engine.

I had just installed a new aftermarket cheapo ignition switch so what the heck? Well, I got a 75 Amp Pushbutton switch and wired it into the start circuit instead of using ignition switch Ign-1 position. Instant start!

Turned out the cheapo aftermarket ignition switch didn't have the ampacity to carry the amperage load to my starter relay to crank a high compression diesel. Well if the switch is that crappy for starting it's hard telling how good the rest of it is?

So I'm suggesting to you all that if you have a strange electrical problem like you just don't have enough voltage or amperage going where you need it don't overlook the ignition switch itself, even if it's brand new! You most likely buy Made in China quality nowadays...