I couldn't open the Terracan links, but I have been suspecting the same thing (PWM signal) for a couple of weeks.

I have plenty of snow for practice, what wire(s) should I monitor?
I think that a few inputs would be in order (front axle, rear axle, ABS, 4Lo) to the TOD ecu.
I'd definately monitor the TOD to clutch solenoid as well.

I figure that this weekend I could get started checking voltages and frequencies under various conditions. It will be difficult to catch a 70/30 or an 85/15 condition however. It seems that TOD is all-or-nothing on ice and snow.

I'll think about a nice spreadsheet for gathering all of this data.

If we get the right information together, I have an extensive inventory of tools and parts to make this happen.
Heck, if it works I might not sell the VX after all.