Autosport Labs

I want to use aux channel input to switch on additional electrical radiator fan. Can I do that? I have one pole engine coolant temp sensor (for temp gauge). But I guess it changes resistance, not voltage. Can I use that one without loosing temp gauge?
Fan has low and high speed relays, and I want to use two programable outputs to first start fan on low, than on high (and perhaps third output to shut off a/c ).

Yes, you can do this. you should use a separate temperature sensor and not piggy-back on the existing one, or you may affect the readings on the dash gauge.

The temperature sensor is wired similarly to the V4- see the graphic here:
http://www.autosportlabs.net/MJLJ_V4_ve ... e_resistor

I thought I could use existing temperature sensor. I am not sure if I can add another one easily.

But if I manage to fit one, Do I just connect wire from sensor directly to "From Sensor or external device" here: http://www.autosportlabs.net/images/1/1 ... ircuit.png

Or do I need some additional electronic?

Yes. you would connect the sensor to the "from sensor or external device" input on that schematic.