Battery Charging

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.

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 does not immediately update the battery state of charge. In this instance, the BMS Reset must be carried out using a diagnostic scan tool. This reset is needed for proper engine off load shedding and to prevent invoking of engine off load shedding earlier than normal.

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.