Postby smj999smj » Fri Oct 30, 2020 11:41 pm
Yeah, looking at the diagram, it would seem pretty simple to wire it up if it's not pre-wired. I'm surprised they don't have the BCM control it. Looks like the one power wire from the ignition switch simply energizes the solenoid side of the relay when they key is "on." The other power wire from the ignition switch supplies the power to the heater switches. The switches divert that power via one or two wires, depending if it's in the hi or lo position, to the grids. As you said, the thermostat closes and opens the circuit based on temperature and it's located in the heater grid assembly.
As far as your SE being pre-wired for it, I don't know, so you'll have to check. It would be nice if it was. I wouldn't expect the LE main harness to be similar to the SE, as the LE has a number of options that the SE doesn't, such as the auto seat positioner and the AUTO mode transfer case.