truck overheated at the carwash...thankfully safety sensor shut it down. Waited 30mins, started her up and drove 2 miles back home. Seems the hi-speed efan isnt coming on. Relays look good on the fans, so assumed it was resistor and if so, gonna revert back to clutch fans!
BUT NOW WONDERING IF ITS A STUCK T-STAT?

I'm so pissed...only got 50 miles out of storage and this happens, then I get a worsening whine as I glide to a stop (but not in neutral) that I think is my transfer case...it was fine under the cover!

 

A relay can look good but not be good, did you check it for operation? What resistor? Do you have a inferred heat gun? or have a friend that has a inferred heat gun? Use the gun to check if the thermostat is stuck. They typically stick in the open position, so I doubt that is your problem.

 

All good questions. As the elec system is what I understand the least, I just switched out the relays 1 at a time and made no diff. I assumed it must be the Hi-speed fan resistor as I was told that they burn out over time if ur fan cycles on and off alot - which mine did...it was on the "to be corrected" list.
At this point...I'm just gonna drop it off and have it once overed!

 

Explain the infrared & thermostat deal. Are u aiming it at the Tstat or the upper & lower rad hoses?

 

+1, t-stats are designed to fail in the open position (although I have seen them seize shut on rare occasions)

I'm curious about this too...I've always checked by physically touching the upper and lower hoses, so I'm assuming that you use the inferred thermometer in the same manner...

 

Ditto.