Ok look I know when the resistor fail, it blows on full speed. That's not it. My blower won't blow at full speed. It works in low.and both mid settings fine. But no full speed. So huh?
does anyone know off hand if the resistor and the straight through are separately grounded

 

So far as I know, the switch itself provides the ground path..... so, if it works on any speed, it should work on every speed.... (the ground, at least.) Might be able to find wiring diagrams for your truck here.

 

Normally, the default failure speed is full speed. Every now and then though, I've seen lower speeds that are rarely used keep working but the speed usually used fails. More often with the electronic resistor blocks. The old thermal wires usually blow full speed or not at all. I tracked down a 2002 Grand Cherokee with a blower problem and it acted like that. It had melted and when that happens, no telling what will happen.