by cmann250 » Fri Jan 03, 2014 8:37 am
I'm thinking about this again.
I tried splicing the thermistor wires and I got manual control of the heaters. A side effect was with the switch open, the original circuit was left open. That resulted in the grid heaters turning on regardless of the temperature and then the WTS light would blink, indicating an open circuit.
I'm back to my original idea. I am going to wire up a "redundant" S21 and S22 that are manually controlled. In doing this, I leave the automated part of the system untouched therefore it should work as before. My manual control circuit will be an undetectable redundant piggyback, more or less. This will allow me to use the grid heaters at 30* and they should still work as the factory intended below 15*.
I feel that I am doing my truck a favor since it sounds like the engine is trying to jump out from under the hood when it's running on 3 cylinders at 30*. I find that with this early design of grid heater control, plugging the truck in for anything less than over night is a waste of time. With it being plugged in for 2 or 3 hours in the morning, the coolant is warmed up and the heat comes on quick, but the truck starts hard. This manual system will let me plug it in if I remember to, yet still start up easily with the grid heaters.
I appreciate the help of those like BobS, but I cannot make sense of electricity from someone else's explanation. I just have to figure it out myself, usually the hard way.
Caleb, Certified Shade Tree Mechanic Extraordinaire
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"Whatever!" - Coach Jerry Smith