I'm still driving with a defective M4 auxiliary fan and/or N65 pulse control module. As I mentioned earlier, there are two motors in this aftermarket M4.

The right motor is hooked to the left with bullet connectors, and I unplugged it so only the left runs. N65 starts the single motor reliably, so I can assume that it thinks that too much current is running to the fan with both plugged in.

However, I did see a >.2V drop between the red supply wire and the black/white fan power input wire during full-power operation (10ma control current). This is with both fans running, so assuming a 10A draw, this would be .02 ohms which is way too large for the SUP75N06 under saturation. As there is nothing else between the power and fan leads, I now strongly suspect that one of these MOSFETS is bad. If the MOSFET has too high of a resistance, it's concievable to me that the circuitry in the N65 would think that the current draw was too high. But I still have no idea how it determines the current draw; I just know that it does.

The local dealer lists the N65 at $179, so I'm not too terribly afraid to cut mine up. I ordered some of these MOSFETS today. Hopefully early next week I'll be able to fix the N65.