This is just some interesting info I came across about how the LVB (12v battery) is monitored.
Battery Load Shed
The BCM uses the battery current sensor to keep track of the battery state of charge. The battery current sensor is a Hall-effect sensor attached to the battery ground cable. When the engine is off, and the BCM determines the battery state of charge is below 40% or 10% of the charge has been drained or 45 minutes have elapsed, a load shed message is sent over the CAN. This message turns off the audio/navigation system to save the remaining battery charge. Under this condition, SYS OFF TO SAVE BATT is displayed on the centerstack infotainment display to notify the driver that battery protection actions are active.
Engine off load shed occurs when the engine is not running, and the ignition is in the ACC or RUN position. To clear the load shed state, restart the engine.
This is a picture of where the Sensor (in Blue) on the 12v battery Ground cable is located.
Edited by GrySql, 08 December 2014 - 07:28 PM.