P1AE5
DTC P1AE5
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (with HP2) (Initial Inspection and Diagnostic Overview)Diagnostic System Check - Vehicle (without HP2) (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptor
DTC P1AE5
- Battery Energy Control Module Hybrid Battery Power Off Control Circuit
Diagnostic Fault Information
Typical Scan Tool Data
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 BECM receives a pulse width modulated (PWM) signal from the HPCM called the contactor system request circuit command. The BECM uses this signal to open and close the high voltage (HV) contactor relays. A 5-volt circuit is provided from the BECM to the HPCM. The HPCM uses a PWM signal on the 5-volt circuit to control the contactor system request command signal. If this PWM signal becomes out of range or invalid, the system will use a redundant GM LAN message to command the HV contactor relays Open and Closed.
Conditions for Running the DTC
* The vehicle power mode is RUN.
* Accessory voltage is 9-18 volts.
Conditions for Setting the DTC
Contactor system request circuit command signal is less than 25 percent
OR
Contactor system request circuit command signal is between 35 percent and 65 percent
OR
Contactor system request circuit command signal is greater than 75 percent
OR
The frequency of the contactor system request circuit command signal is not between 247 Hz to 253 Hz for 2 out of 3 seconds.
Action Taken When the DTC Sets
DTC P1AE5 is a Type C DTC.
Conditions for Clearing the DTC
DTC P1AE5 is a Type C DTC.
Diagnostic Aids
* When the percent duty cycle of the contactor system request circuit is 65-75 percent, the BECM will request the 300 volt battery contactors to OPEN.
* When the percent duty cycle of the contactor system request circuit is 25-35 percent, the BECM will request the 300 volt battery contactors to CLOSE.
* The frequency of the PWM signal must be between 247 Hz to 253 Hz to be valid.
Reference Information
Schematic Reference
Hybrid Controls Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, observe the hybrid battery Contactor System Request Circuit Command parameter using a scan tool. The contactor system request commanded value should be 30 percent.
2. Ignition ON, observe the DTC information with a scan tool. DTC P1AE5 should not set.
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. Verify if DTC P2534 is set.
• If DTC P2534 is set, refer to DTC P2534 (P2534).
2. Ignition OFF. remove the drive motor generator control module assembly sight shield.
3. Disconnect the harness connector X1 at the drive motor generator power inverter module (PIM) assembly.
4. Ignition ON, test for 4.9-5.1 volts between the contactor signal circuit terminal 4 X1 and ground.
• If less than the specified range, test the circuit for an open or a short to ground. If the circuit tests normal, replace the drive motor generator battery control module.
• If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the drive motor generator battery control module.
5. If all circuits test normal, replace the PIM module.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Drive Motor Generator Control Module Sight Shield Replacement (Drive Motor Generator Control Module Sight Shield Replacement)
* Control Module References (Programming and Relearning) for control module replacement, setup, and programming.