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 theft deterrent module (TDM) sends the fuel continue password to the engine control module (ECM) via the serial data circuit. The ECM compares this password to the learn password. If the learned password matches the password received from the TDM, the ECM will allow vehicle starting.