Theory Of Operation
WARNING: This page is about a different car, the 2012 RAM Pickup. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) receives a constant voltage from the batteries through the battery wires that are connected directly to the positive (+) battery post. The PCM receives switched battery input through the vehicle Ignition Switch wire when the vehicle is turned on. The PCM will illuminate the ETC lamp immediately after the diagnostic runs and fails. During the time the customer may experience some performance effects such as engine dying or hard starting. Fault information, trip information could be inaccurate.