2011 Chevrolet Truck Silverado 1500 WT 2WD 4.3L FI OHV 6cyl is overheating while idling.
It takes about 2-3 mins, so drive thrus and multiple red lights back to back are the main culprits.
I believe that the problem is the radiator fans are not turning on when the engine temperature becomes elevated.
Troubleshooting so far
Fuses are all good.
When I idle the truck and it reaches normal operating temperature (210-212F) the fan never turns on and will eventually start creeping up (temperature measured on the dashboard)
Relays appear to be working correctly. However, I can short the circuit in the relays to get the radiator fans blowing. Short circuiting both 86 to 87 and 30 to 85 will get the fans blowing. (see image below)
After measuring the voltages in the relay socket using a multimeter, it appears that there is no input voltage in 30/87/87a. I believe; however, that there should be power in 30 when the truck is idling past 210 degrees.
This makes me believe that it is the ECM or the coolant temperature sensor. However, my dashbaord temperature is still providing me with (what seems to be) accurate temperature information. And I assume that the temperature information is coming from the coolant temperature sensor. (is that correct)
I don't know how to trouble shoot if it is the ECM or the coolant temperature sensor, or even if the trouble shooting I have done thus far is even in the right direction. I just am kinda stalled out right now and don't know what direction to head in towards fixing this issue.