Theory Of Operation
WARNING: This page is about a different car, the 2014 Fiat 500e. However, it is still accessible from the selected car via links, so may be relevant.
The Body Control Module (BCM) is the Local Interconnect Network (LIN) master for the humidity sensor. The humidity sensor detects humidity, dew point and windshield glass temperature, and sends this information to the BCM. The BCM then broadcasts the message over the Controller Area Network (CAN) data bus. The repair of this fault condition does not involve any external circuitry and centers on verifying the integrity of the internal circuitry and software validity.