Circuit/System Description
WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The torque converter clutch (TCC) signal circuit is a high voltage input to the body control module (BCM), engine control module (ECM) and transmission control module (TCM). The ECM monitors the stop lamp switch circuit to detect when the brake pedal has been applied. The BCM monitors the stop lamp switch to determine when the brake pedal is applied. When the brake pedal is applied, the BCM sends a GMLAN serial data message to the ECM indicating that the brake pedal has been applied. The ECM senses a high voltage signal on the TCC signal circuit when the brake pedal has been applied.