Battery Management While The Ignition Switch Is In LOCK (0) With Electrical Devices ON

WARNING: This page is about a different car, the 2013 Acura MDX, 2012 Acura MDX, 2011 Acura MDX, and 2010 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.

When the battery sensor detects the battery voltage decreasing, that information is sent to the gauge control module via the UART line. The gauge control module then operates a beeper, and displays the message "SWITCH OFF ALL LIGHTS AND ELECTRICAL DEVICES" on the multi-information display (MID) to inform the client that electrical devices should be turned off. If electrical devices are not turned off and the battery voltage decreases more, the gauge control module sends an interior lights off signal to the MICU, the rear MICU, and/or the driver's MPCS unit via the B-CAN line (the front passenger's MPCS unit receives that signal from the driver's MPCS unit via the UART line). Based on that signal, the units cut off the ground circuits of the interior lights and turns them off.

Fig 1: Battery Management System Diagram - While Ignition Switch Is In LOCK (0) With Electrical Devices ON

Courtesy of AMERICAN HONDA MOTOR CO., INC.