Diagnostic Instructions

DTC Descriptors

DTC P1A22: Hybrid Battery 1 Circuit Low Voltage

DTC P1A23: Hybrid Battery 1 Circuit High Voltage

DTC P1A29: Hybrid Battery 2 Circuit Low Voltage

DTC P1A2A: Hybrid Battery 2 Circuit High Voltage

DTC P1A30: Hybrid Battery 3 Circuit Low Voltage

DTC P1A31: Hybrid Battery 3 Circuit High Voltage

Circuit/System Description

The battery energy control module (BECM) monitors the 3 module voltage sensors for low or high voltage condition.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

P1A22

Module 1 voltage raw A/D is less than 0.5 volt.

P1A23

Module 1 voltage raw A/D is greater than 4.5 volts.

P1A29

Module 2 voltage raw A/D is less than 0.5 volt.

P1A2A

Module 2 voltage raw A/D is greater than 4.5 volts.

P1A30

Module 3 voltage raw A/D is less than 0.5 volt.

P1A31

Module 3 voltage raw A/D is greater than 4.5 volts.

Action Taken When the DTC Sets

Hybrid system is inactive.

Conditions for Clearing the DTC

Module voltage raw A/D returns to normal operating range.

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

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:

1. If there are any other DTCs set as current, diagnose those first, including any clearing of codes.
2. Verify that the DTC is set as current.
3. Scan and record the hybrid battery voltage parameters for battery 1, battery 2, and battery 3.
4. Measure the voltage of the battery that set the DTC and compare it to the parameter scanned value. Refer to Generator Battery Temperature Sensor Replacement

⇒	If the voltages are within 0.5 volt, replace the battery pack.

5. Disconnect harness connector X2 from the BECM. Refer to Hybrid Battery Service Disconnect/Connect .
6. Test for 1.3-1.7k ohms between the following circuits:

•	X2 terminal 1 to Generator Battery 1-X1

•	X2 terminal 11 to Generator Battery 1-X2

•	X2 terminal 2 to Generator Battery 2- X2

•	X2 terminal 12 to Generator Battery 3- X2

⇒	If not within specified range, replace the harness assembly.

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.