Greetings again from Amarillo, where the part store clerk's ask "who makes that" (Prius). Happened three times. I'm to the steps of removing codes so I can get on the road. It looks like I need to put in a resistor of some level to let it think that the heat res is still there. I have had to temporarily remove it. Any ideas of the range of resistance? I'm down to picking up some sort of sensor from the auto parts store or if there is a radio shack store in town picking up a resistor. Thanks for your thus far.
Unfortunately the schematics don't give the actual resistance range of the thermistor. What they do give is the voltage on the pins of the plug, which says @ 20C gives .5-3.4V @ 60C gives .2-1.0V Seems like a wide tolerance. As a hack to get things going you might try a 10k potentiometer, and adjusting it to the lower of those numbers. It is such a wide tolerance though, that I might just try shorting the thermistor wires together. The actual thermistor value is probably on the order of a few hundred ohms at high temps.
A diode drop would be from about 0.5V (if it's really low current) to 0.7V (if it's above a few mA). You might want to just put a diode in there (instead of a resistor). If it works, great! If not, reverse it and it should work.
