The IPC determines that the system voltage is less than 11 volts or greater than 16 volts. The
IPC receives a class 2 message from the body control module (BCM) indicating there is a
system voltage range concern.
The IPC performs the displays test at the start of each ignition cycle. The indicator
illuminates for approximately 3 seconds.
The ignition is ON, with the engine OFF.
The generator battery control module determines there is a fault and sends a class 2 message
to the IPC to illuminate the charge indicator.
Charging System Failure
The generator battery control module will send a message to the IPC for the CHARGING
SYSTEM FAILURE message to be displayed. It is commanded ON when DTC B1487 sets. The
message is turned off when the conditions for clearing the DTC have been met and after an
ignition cycle.
Service Charging System
The generator battery control module will send a class 2 message to the IPC for the SERVICE
CHARGING SYSTEM message to be displayed. It is commanded ON when DTC B1390,
B1488, B1492, or B1516 sets. The message is turned OFF when the conditions for clearing the
DTC have been met and after an ignition cycle.
Voltmeter Operation
The IPC displays the system voltage as detected at the ignition 1 input of the IPC. When the
engine is ON, the gage should be between 10-16 volts. The voltmeter will be noticeably different
than previous model year vehicle as far as voltage fluctuations. If there is a concern with gage
operation ensure to compare to a known good like vehicle.
ELECTRICAL POWER MANAGEMENT DESCRIPTION AND OPERATION
Electrical Power Management
The electrical power management (EPM) is used to monitor and control the charging system and
alert the driver of possible problems within the charging system. The EPM system makes the most
efficient use of the generator output, improves the battery state of charge (SOC), extends battery
life.
see if they set a DTC when the battery voltage is too high or too
low.
2008 Hummer H3
2008 ENGINE Engine Electrical - H3