P1A4E

DTC P1A4E

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (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 P1A4E
- Battery Energy Control Module Hybrid Battery System Voltage High




Circuit/System Description

The battery energy control module (BECM) monitors the hybrid battery system for an overvoltage condition. A diagnostic is running continuously to verify that the battery pack voltage is not above 52 volts. DTC P1A4E will set if the diagnostic detects that the voltage is above 52 volts.


Conditions for Running the DTC

The ignition is in the RUN position.


Conditions for Setting the DTC

Hybrid battery pack voltage greater than 52 volts.


Action Taken When the DTC Sets

Does not affect hybrid system operation


Conditions for Clearing the DTC

Hybrid battery pack voltage returns to normal operating range.


Reference Information
Schematic Reference

Hybrid Energy Storage Schematics ()
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
Special Tools

J 35616 GM Approved Terminal Test Kit


Circuit/System Testing

Caution: To help avoid personal injury, additional precautions must be taken prior to working on the generator control module or the generator starter. After removing the 36V battery cables from the generator battery, remove both engine wiring harness connectors from the generator control module. Wait at least 5 minutes and then remove the generator control module cover. Verify voltage levels at all 36V, 12V, and 3-phase connections, are less than 3 volts using a DMM before proceeding.


Caution: To help avoid personal injury, be careful when working in the vicinity of the generator battery disconnect control module. Internal components will still be live, 36V potential, even when the cover has been opened or removed.


Important: In order to avoid damaging BECM X1 and X2 connector terminals, the proper test probes should be used. The proper test probes are as follows:



* J-35616-65B for female terminals
* J-35616-64B for male terminals


1. Verify the DTC is set as current.

• If the DTC is history, refer to Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics).

2. Scan and record the hybrid battery pack voltage.
3. Measure the voltage between ring terminal 3 and ground. Should read less than 52 volts. Refer to Hybrid Battery Service Disconnect/Connect ().

• If greater than the specified value, replace the battery pack.

4. Disconnect harness connector X1 from the BECM.
5. Test for 1.3-1.7k ohms between the following circuits:

* X1 terminal 1 to ring terminal 7
* X1 terminal 11 to ring terminal 6
* X1 terminal 2 to ring terminal 5
* X1 terminal 12 to ring terminal 4


• If not within specified range, replace the voltage sensor harness assembly.

6. If all circuits test normal, replace the BECM.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.


Generator Battery Replacement ()