Circuit/System Description
WARNING: This page is about a different car, the 2010 Pontiac G5 and 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
The transmission control module (TCM) and the engine control module (ECM) monitor the number of Engine Speed Request Circuit serial data messages transmitted/received between modules. If the ECM detects a faulty message count, DTC P150C sets.