In Reply to: Re: Another look at the resistor posted by Jack - Iowa on January 25, 2019 at 08:11:47:
Never mind, my bad. My initial impression was the wiring to top active resistor terminal posts were backwards. The RED coil wire should be to the LH post, the ignition switch RED w/BLACK TRACER wire to the RH resistor post, as viewed from front of tractor. Then I realized it doesn't matter electrically as resistors are not polarized. I think it does matter in a real life scenario as to which tractor model, which wiring harness is used, as the wiring harnesses were different depending on location of key switch. The early 9N had the ignition switch on the upper RH dash panel. It got moved to the LH side and then to the steering column. The 8N switch is on the lower LH dash. Wiring Harnesses don't allow much wiggle room as they are so having the correct one seems more important. I've worked with aftermarket harnesses and had issues with one or two wires coming up a tad short. The OEM 9N/2N switch wires are BLACK w/RED TRACER to LH resistor post and YELLOW w/BLACK TRACER wire to the resistor bottom junction post. My 8N MPC shows the ignition switch wires as YELLOW, to bottom junction, and RED w/GREEN TRACER, to RH top resistor post. Not a big tech issue, just saying. Also, the only differences between the 9N ballast resistor and the 8N unit are the mounting screws. I don't believe there are any electrical value differences -shouldn't be anyway.