Diagnostic Instructions
DTC Descriptor
DTC P0AA2: Hybrid Battery Positive Contactor Circuit Stuck Open
Circuit/System Description
The engine control module (ECM) monitors to detect when it can no longer control the state of the contactor.
Conditions for Running the DTC
Engine ON
Conditions for Setting the DTC
| • | The diagnostic fails when then the BECM does not respond to the ECMs CLOSE command. |
| • | 3 seconds after the contactor has been commanded to CLOSE, if the contactor status at any time does not read as CLOSED, the diagnostic will fail. |
| • | If the service disconnect is active, the diagnostic will fail. |
Action Taken When the DTC Sets
The hybrid system is disabled.
Conditions for Clearing the DTC
| • | The contactor status is CLOSED while the contactor is commanded to CLOSE. |
| • | The condition responsible for setting the DTC no longer exists. |
| • | The ignition must be cycled before the DTC can be cleared. |
Reference Information
Schematic Reference
Hybrid Energy Storage Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Generator Battery Carrier Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Diagnostic Aids
This diagnostic also fails when the BECM refuses to obey the ECM’s CLOSE command. The contactor can be reported as Closed, Impact Detected, Service Disconnect, Open, Overtemperature, and Fault, and the BECM sets this status.
If the DTC is current, check the status of the contactor using the scan tool. If the status is Service Disconnect, verify that the service disconnect is fully engaged by the BECM cover when closed. If this diagnostic is accompanied by hybrid battery temperature
circuit DTCs, diagnose those DTCs first. If the vehicle was in an event where the airbag deployed, the crash event must be deasserted in vehicle communications before the contactor will be allowed to close. If the contactor status is Fault, then there may be
an issue with the battery disconnect unit.
If the DTC is in history with no other faults, or the BECM cover was fully seated, Inspect connections at the BECM harness for X2.
Circuit/System Testing
- If other DTCs are set diagnose those first.
- With a scan tool, clear the DTC.
- Cycle the ignition switch from OFF to RUN several times.
- Ignition ON, operate the vehicle within the Conditions for Running the DTC and verify the DTC does not reset.
| ⇒ | If the DTC resets, replace the BECM. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for BECM replacement, setup, and programming.
