Circuit/System Description

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The drive motor generator battery control module will diagnose its own systems and determine when a fault condition is present. Diagnostics and system status is communicated from the drive motor generator battery control module to the drive motor generator control module through the serial data circuit. The drive motor generator control module is the host controller for diagnostic trouble code (DTC) information.

The vehicle is equipped with a high voltage (HV) isolation monitor feature. The purpose of the HV isolation circuit is to test the resistance between the HV positive and negative direct current (DC) bus and chassis ground. The drive motor generator battery control module only runs this test when the ignition transitions from ON to OFF the HV contactors have opened and the drive motor generator battery control module is still awake. The drive motor generator battery control module has an internal Isolation sensor that measures the resistance between the HV DC positive and negative bus and chassis ground. The drive motor generator battery control module runs an internal self check of this sensor circuit. If the internal self check fails DTC P1AE7 will set. This DTC indicates that the fault is in the drive motor generator battery. Because this diagnostic runs after system power down, the diagnostic status does not get reported until the next ignition cycle.