IMT Fan Position Signal Circuit
WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.
When the IMT valve is rotated the hall-effect sensor is reporting the position of the valve to the engine control module (ECM). The control module uses this feedback signal to determine the position of the IMT valve.
The control module compares the commanded state of the variable tuning signal circuit and compares it to the IMT Fan Position Signal Circuit for being stuck open, stuck closed.