Ahhh....I got it!!

After a bunch more research and another call to the SPAL tech support line, I got a wiring diagram which does exactly what I want it to do......it controls both the low speed and high speed powers of the fan! And, you were all about right...a couple of relays, controlled by the grey wire to run high amp power directly to the fan (without having the high amp power going through the controller).

It modulates the low speed fan power through the fan ground (-) until the temps get to within 10-degrees of the "max" setting, that I've programmed into the SPAL controller, then it kicks in the high speed on the fan, at 100% power, until the temps drop down to 10-degrees below the "max" temp setting. When the temps get down below that threshhold, the controller goes back to modulating the power to the low speed wire on the fan. It's perfect, exactly what I wanted it to do in the first place.

I kept getting hints from here and Pirate that there was a solution for this issue...using the SPAL controller....but it took a call to the tech support line to get the wiring diagram.

It's funny, I started talking about my problem and as soon as I mentioned I had a "Taurus fan" the guy knew exactly what I was trying to do and exactly what I needed....he even e-mailed me the wiring diagram. I must have spent 3 hours searching bulletin boards for a wiring diagram or even just a description of how to wire it all up...and got nothing. All the posts mentioned that a relay was needed (which I knew)....but all were focuses on controlling only one speed of the 2 speed Taurus fan....and even with those you could either modulate the low power or only have 100% high power.

The tech guy also mentioned a few interesting things about the Taurus fan. The thing draws around 100-amps on start-up of the high power. But, the way their wiring diagram is set up, the fan is already spinning when the high spped kicks in, so you only have to deal with about 40 amps. All the posts I read said a 70 amp relay and fuse were needed to handle the high power start up. the Tech support guy told me that if you go that route you also need to buy a fire extinguisher for the resulting fire.

I'm having a few computer problems at the moment, so I can't post the PDF. But if anyone is interested, send me a PM and I'll forward the PDF of the wiring diagram.

Thanks for the help, as usually