Need Help Validating Eec Behavior - Someone Lend An Easy Hand?

Hi, I need help validating expected EEC behavior in order to troubleshoot an issue... can someone with a 5.0 follow the very simple steps below and let me know if the fan comes on?

Step 1 - Turn key all the way on, but do NOT start car
Step 2 - Unplug ECT sensor (its right above the thermostat housing in the metal heater line)

Based on all that I have read, it is my understanding that the fan should come on as soon as the sensor is unplugged (regardless if the engine is running, and regardless of engine temp) as a safety control to protect the engine temp if the ECT sensor should fail.

I need to validate this expected behavior as I am having issues getting my fan to work and when I perform these steps, my fan is NOT coming on.

Thank you in advance to anyone that can help me!

jozsefsz said:

It's my understanding that that's what's supposed to happen. My car's in storage for the winter so I can't help test it, perhaps someone else can. I can tell you however that running the KOEO test will also spin up the fans, and that it's often easiest to work your way backwards in the fan circuit (apply 12v to fan, check wiring / circuit breaker / CCRM), and the last suspect is typically the EEC..

Click to expand...

Thank you, agreed! And all has been done to this point, and checks out fine. At this point I suspect the EEC is the root cause, but likely through an issue with a dependant circuit (vehicle speed sensor for example) which is part of the if-then logic of the EEC fan control.

Validating this KOEO behavior will help me know when I've discovered the issue and fixed it without having to heat the car up.