I am doing some much needed work on an 86 Mits. MM and during thsi adventure the truck's starter has began to crank over while key is in the RUN position and stops cranking in the START positon. Accessories work and everything else seems ok.
So far I have replaced the following items.
Installed Fuel Pump - Carter.
Installed Fuel Regulator - Holley.
Installed 3 terminal oil safety switch.
Installed Distributor - '86 to a '87
Installed another ignition switch in steering column.
Installed Alternator - 50amp to a 87-89 Starion/Conquest 100 amp. (changed the rear 2 wire plug to fit updated alt)
Installed Exhaust Manifold - cracked '86 to a good '87.
Installed Starter & Solenoid - bad '86 to a working '87.
Hooked up driving lights to relay.
Removed un-needed Ballast Resistor on a 3.0 Ohm Flame Thrower coil.
Replaced old past installed accessories & wiring and installed new relays, engine bay fuse block.


Now everything worked fine that was replaced above, but the truck is now cranking the starter over while in the run position. I tried another ignition harness in the steering column an it still cranks over in RUN and stops cranking in START positon. There is no burning fuses, lights are all working, starter sounds great when cranking and voltage gauge shows a normal drop while it spins. I have not moved any wires out of their normal position in ignition or in engine bay. Getting 12 volts to coil and starter, but not while in the START position. I have now bypassed the oil safety switch until problem is corrected, Ohm readings on the coil are in specs.
I need to re-check the new alternators wire color code on the plugin behind alternator and make sure they are not reversed somehow, but it seems fine right now. I am just tracing my steps to see what possibly could of got crossed up.
If you have had this happen, go ahead and chime in and let me know what you did to correct it.
I may run some test leads from ignition switch to coil (hotwire) and starter and see if this corrects the problem, if it does then there is a wire fouled up wire somewhere. If it doesn't, I'm still at step one again. The ignition switch works in accessory, but soon as it clicks over to run, it eguages starter.

This is a diagram below that best represents my wiring, though my smog is removed and the diagram also shows extra items that are not installed on my truck.
I have a 5 speed as well.

wiring.jpg