Engine Off 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%, 10% of the charge has been drained or 45 minutes have elapsed, a load shed message is sent over the Controller Area Network (CAN). This message turns off the audio system to save the remaining battery charge. Under this condition, a message may be displayed on the IPC or center stack display to alert the driver that battery protection actions are active.

When charging the vehicle battery by connecting the charger to the negative battery terminal is necessary , such as when using a combination battery charger and battery tester/analyzer, like the GR 1 190 V3.0 Intelligent Diagnostic Charger, the BCM will not immediately update the battery state of charge. In this instance, after charging, you must CARRY OUT the Battery Monitoring System (BMS) Reset using the scan tool. This reset is needed for proper engine off load shedding and to prevent invoking of engine off load shedding earlier than normal.

NOTE: If the reset is not carried out, when the battery is charged by connecting the charger to the negative battery terminal, it takes approximately 8 hours for the BCM to learn the new battery state of charge. During this 8 hour period, the vehicle must be undisturbed, with no doors opened or keyless entry button presses. If the vehicle is used before the BCM is allowed to learn the new battery state of charge, engine off load shedding can still occur and a message may be displayed.

When charging the vehicle battery by connecting the charger to engine or chassis ground , the negative charger clamp must be connected to an unpainted chassis surface or a solid engine component such as a generator mount or engine lifting eye. In this instance, after charging, the BMS Reset is not required. Through this method of charging the BCM updates the battery state of charge during the charging process.