Need help with this one dealer not able to find problem.
My vistronic engine fan is not engaging at all!!
-truck has new waterpump,coolant fluid,thermostat,engine temp sensor and new fan clutch.
-no check engine light is on.
-electrical test found 12v supply -good
-5v signal for speed sensor -good
-sensor ground supply from engine control module-5ohms
-supply voltage to pin #5 at drive fan at 5v
--does anybody know if the fan clutch control signal is a ground signal?
--should the fan come on with AC on?
--should fan come on with coolant temp sensor disconnected?
I know those are a lot of questions,but I am getting very desperate since the truck can not be used right now.
Thanks for your help

 

The Engine Control Module (ECM) controls the level of engagement of the electronically controlled viscous fan clutch by monitoring coolant temperature, intake manifold temperature, air conditioning pressure and transmission oil temperature. Based on cooling requirements, the ECM sends a signal to the viscous fan clutch to increase or decrease the fan speed.
Fan speed is monitored by the ECM. Fan speeds above or below a calibrated threshold will set a DTC. Circuit concerns will also set fan clutch DTC's.

If there were a problem with the fan it should set a code for fan speed. I would check the radiator for a clog. It should be hot all over and no cool spots anywhere.