P1AE6
DTC P1AE6 or P1AE7
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P1AE6
- High Voltage Isolation Fault Detection Circuit Failure
DTC P1AE7
- High Voltage Isolation Fault
Typical Scan Tool Data
Circuit/System Description
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 battery energy control module (BECM) only runs this test when the ignition transitions from ON to OFF and the contactors are open on power down sequence. 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 a self check of this sensor circuit. 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 detected by the BECM. This DTC indicates that the fault is in the drive motor generator battery.
Conditions for Running the DTC
* Accessory voltage is 9-18 volts.
* The ignition switch transitions from ON to OFF.
Conditions for Setting the DTC
P1AE6
The isolation resistance sensor circuit internal to the BECM has failed its functional test.
P1AE7
The BECM has detected a loss of isolation between the high voltage positive or negative bus to chassis ground.
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.
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. 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. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P1AE6 is not set.
^ If DTC P1AE6 is set, replace the BECM.
2. Verify that DTC P0C76 is not set.
^ If P0C76 is DTCs set, repair that first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle. Diagnostic Trouble Code Descriptions
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.
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.
3. Remove the drive motor generator battery case upper cover.
4. 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 BECM.
5. Enable the high voltage, refer to High Voltage Enabling.
6. 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. Verification Tests
* Drive Motor Generator Battery Replacement.