i think im having a fan issue,i keep getting a code,fan speed not the same as engine,and at highway speeds i see the temps are a bit higher,is there a way to test to see if the fan i locking up?or is there a way to manually lock it,iwould like to lock it for the summer months,i would sacrifice a few hp to get a cooler running engine.

 

Here's how to check, just do step #6 unless you DRB access.

NOTE: The following test may take up to 15 minutes
to perform.
The engine should be at normal operating temperature.
(1) Set the parking brake and verify the transmission
is in park or neutral.
(2) Set air conditioner (if equipped) and blower fan
to OFF.
(3) Start and allow engine to reach normal operating
temperatures.
(4) Stop engine, connect the DRB III and select
appropriate model year and engine option.
(5) Check for and correct existing DTC’s
(6) Using Tool 6801, connect pin 1 of the electronically
controlled viscous fan drive connector, located
at the lower fan shroud to battery ground (Fig. 35).
(7) Using the DRB III, verify that DTC 0480 set.
(8) Start the engine.
(9) Go to the SENSOR screen and observe the fan
speed.
(10) Run the engine at 2500 rpm.
NOTE: It maybe take 15 minutes before fan speed

After a few minutes with pin 1 grounded when increasing engine speed you should see and hear the fan speed up also.

One more thing checked the wires going from the fan clutch down to the connector on the shroud they may have been cut.