Anyone see a problem running a 4 wire with only the signal wire connected? I don't plan on running the 4 wire all the time, I just need to have it on there for a few days and don't feel like running power/ground to it.

 

I think it needs the heater circuit. I tried to test a 4-wire by connecting a voltmeter to it out of the car and using a propane torch to see it react and I got no reaction to the flame. I tested it again in the car and it worked. So I don't know if I was doing something wrong or not.

Easy to test. Plunk it into the car and run a voltmeter to see if it dithers at idle.

Cliff Knight on m.net has some information about testing and how they work on a webpage somewhere.