have 12 volts going to blower motor control processor but no voltage on p/w wire (controls speed of blower motor) as I vary the fan speed on controller head.Can I assume the controller head is faulty or are there other modules involved here.Also (this may or may not be connected to blower problem but seems to have appeared at about the same time as blower problem), the 4x4 control panel sometimes starts up in 4x4 when I start the truck even though I left it in 2x2 when I shut down.