Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P1AE5: Battery Energy Control Module Hybrid Battery Power Off Control CircuitDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Contactor Command PWM Signal | P1AE5 | P1AE5 | P1AE5 | P1AE5 |
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Accessory voltage is 9-18 volts, vehicle power mode is RUN Parameter Normal Range: 30% or 70% | |||
Contactor Sys. Req. CKT Command | 0% | 100% | 100% |
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 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
| • | The BECM will set contactor status to OPEN when the percent duty cycle is 65-75 percent. |
| • | The BECM will set contactor status to CLOSED when the percent duty cycle is 25-35 percent. |
| • | The frequency of the PWM signal must be between 247 Hz to 253 Hz to be valid. |
Reference Information
Schematic Reference
Hybrid Energy Storage Schematics
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Special Tools
EL-48900 HEV Safety Kit
Circuit/System Verification
- 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.
- Ignition ON, observe the DTC information with a scan tool. DTC P1AE5 should not set.
- 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
- Verify if DTC P2534 is set.
- Ignition OFF. Remove the drive motor generator control module (DMCM) assembly sight shield. Refer to Drive Motor Generator Control Module Sight Shield Replacement.
- Disconnect drive motor generator power inverter module assembly (PIM) connector X1.
- Ignition ON, verify that the contactor system request command parameter indicates 100 percent using a scan tool.
- Connect a 3A fused jumper wire between the control circuit X1 terminal 4 and ground. Verify that the Contactor System Request Command parameter indicates 0 percent.
| ⇒ | If DTC P2534 is set, diagnose this DTC first. |
| ⇒ | If the display is less than the specified range, test the control circuit for a short to ground. If the circuit tests normal, replace the drive motor generator battery control module. |
| ⇒ | If the display is greater than the specified range, test the control circuit for a open or short to voltage. If the circuit tests normal, replace the drive motor generator battery control module. |
| ⇒ | If the specified range is displayed, replace the PIM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
Control Module References for drive motor generator battery control module or drive motor generator power inverter module assembly replacement, setup and programming
