Theory Of Operation
WARNING: This page is about a different car, the 2016 Dodge Durango. However, it is still accessible from the selected car via links, so may be relevant.
The Body Control Module (BCM) receives a communication network message from the Steering Column Control Module (SCCM) requesting turn signal lamp illumination. When this bus message is received, the BCM provides a pulsed voltage output through the rear turn signal control circuit. The rear turn signal control circuit connects to the Turn Signal Lamps.