so if you put power directly to the fan motor it will run???

if so then your problem is here :
The engine coolant temperature sensor sends an input on a G wire to pin C0636-22 on the
ECM.
The engine coolant temperature sensor is earthed on a RB wire to pin C0636-21 on he ECM.

The sensor is located down on the block, to the rear left side of the AC compressor.

 

Yes the fan will run, it just doesnt seem to run when its supposed to. So is this where I change the sensor and see if I get results?

 

Fan is single speed, so sensor won't make it run any faster.

You see it spinning at crank up because viscous clutch is fully engaged and main fan is sucking as hard as it can. As truck warms up the fan roar drops off and the main fan slows.

The sensor that runs the electric fan is the same sensor that runs the dash heat gauge.

 

There is a relay and fuse involved, F5 (40 amp) in under hood fuse box, and the relay number 4 in same box. You could swap relay 3 & 4 (head lamp wash). The ECU simply supplies a ground to command the relay on. It will get $$$ if the ECU is bad on that particular output. Jumping the wrong contacts in the relay base could burn circuit board traces off inside the ECU or take out a semiconductor device assigned relay driver duty. The ECU is built to switch on the mighty relay coil, which is not anywhere close to the inrush amps of the fan motor.

 

Been following the thread because I found my fuse blown. Put a new one in and aft 15-20 minutes at idle and 195f on ultra gauge the fuse blew again. I'll check if the fan is locked up. If no, what do I do next. I'm not an electrical guy.

 

Spins freely 1/2 around the is very hard. Assume I have a bad fan. Is it difficult to replace?