Diagnostic Instructions

DTC Descriptors

DTC P1AE6: Battery Energy Control Module Hybrid Battery Voltage Isolation Sensor Circuit

DTC P1AE7: Battery Energy Control Module Hybrid Battery Voltage System Isolation Lost

Typical Scan Tool Data

300V Isolation Test Status

Circuit	Short to Chassis Ground	Open	Short to Voltage
Operating Conditions: Accessory voltage is 9-18 volts, vehicle power mode is RUN Parameter Normal Range: Passed
High Voltage DC Circuit	P1AE7	--	--

Circuit/System Description

The drive motor generator battery control module is also referred to as the battery energy control module (BECM). The BECM will diagnose its own systems and determine when a fault condition is present. Diagnostics and system status is communicated from the BECM to the hybrid powertrain control module (HPCM) through the Hybrid LAN communication circuit. The HPCM 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 BECM only runs this test when the ignition transitions from ON to OFF the HV contactor relays have opened and the BECM is still awake. The BECM has an internal Isolation sensor that measures the resistance between the HV DC positive and negative bus and chassis ground. The BECM runs an internal self check of this sensor circuit. If the internal self check fails DTC P1AE6 will set. The BECM sends an AC signal over the DC bus and monitors its amplitude. A low amplitude or collapsed return signal indicates a loss of resistance to chassis ground and a loss of isolation will be indicated by the BECM. 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 key cycle.

Conditions for Running the DTC

Conditions for Setting the DTC

P1AE6

The isolation resistance sensor circuit internal to the BECM has failed its functional test.

P1AE7

Action Taken When the DTC Sets

DTCs P1AE6 and P1AE7 are Type C DTCs.

Conditions for Clearing the DTC

DTCs P1AE6 and P1AE7 are Type C DTCs.

Diagnostic Aids

A single high voltage contactor relay stuck closed can set this DTC. If a high voltage contactor relay is closed when the BECM runs this test, the circuitry in the power inverter module will cause a loss of isolation to be detected.

Reference Information

Schematic Reference

Hybrid Energy Storage Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL-48900 HEV Safety Kit

Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. DTC P1AE6 or DTC P1AE7 should not set.
2. Observe the scan tool parameter 300 V Isolation Test Status. The scan tool should indicate Passed.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Are you preparing the drive motor generator battery for shipment?

⇒

If you are preparing the drive motor generator battery for shipment, Install the terminal extension cover assembly, using UL® listed or equivalent insulation tape rated at a minimum of 600 volts, tape over the manual disconnect opening and the HV cable openings on terminal extension cover. Remove the drive motor battery assembly, refer to Drive Motor Generator Battery Replacement.

⇒	If you are not preparing the drive motor generator battery for shipment, continue with diagnosis.

2. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P1AE6 is not set.

⇒	If DTC P1AE6 is set, replace the drive motor generator battery control module.

Danger: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.

The High Voltage Disabling procedure will perform the following tasks:

•	Identify how to disable high voltage.

•	Identify how to test for the presence of high voltage.

•	Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.

Failure to follow the procedures exactly as written may result in serious injury or death.
3. Ignition OFF, disable the high voltage at the drive motor generator battery. Refer to High Voltage Disabling. Verify that the high voltage contactor relays are not stuck closed.

⇒	If a contactor relay is stuck closed refer to High Voltage Contactor Relay Always Closed.

4. Remove the drive motor generator battery case upper cover. Refer to Drive Motor Battery Case Upper Cover, Front Cover, and Right Side Cover Replacement.
5. Visually inspect the high voltage dc cables internal to the drive motor generator battery for damage or short to chassis ground.

⇒	If any of the high voltage (HV) cables are visually observed as being damaged or grounded, replace the HV cables as necessary.

⇒	If the high voltage (HV) cables are not visually observed as being damaged or grounded, replace the drive motor generator battery control module.

6. Enable the high voltage, refer to High Voltage Enabling.
7. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P1AE7 does not reset.

⇒	If DTC P1AE7 is set, replace the drive motor battery assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.