Circuit/System Description
WARNING: This page is about a different car, the 2009 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
The theft deterrent module (TDM) monitors the battery positive (B+) circuit. If the voltage at the TDM is between 6 and 9 volts, and the voltage being reported by the serial data message is greater than 9 volts, DTC B1424 00 will set.