P1A33
DTC P1A25, P1A2C, or P1A33
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 Descriptors
DTC P1A25
- Hybrid Battery 1 Voltage Performance
DTC P1A2C
- Hybrid Battery 2 Voltage Performance
DTC P1A33
- Hybrid Battery 3 Voltage Performance
Circuit/System Description
The battery energy control module (BECM) performs a rationality check for the module voltage sensor 1, 2, and 3. If the voltage is not valid, the appropriate DTC will set.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
P1A25
* Module Voltage 1 - Module Volts Average is greater than 6 volts.
* Module Volts Average = (MIDDLE (ModVolt1, ModVolt2, ModVolt3) + (PackVoltage/3) + (PowerElectronicsVolt/3)/3.
P1A2C
* Module Voltage 2 - Module Volts Average is greater than 6 volts.
* Module Volts Average = (MIDDLE (ModVolt1, ModVolt2, ModVolt3) + (PackVoltage/3) + (PowerElectronicsVolt/3)/3.
P1A33
* Module Voltage 3 - Module Volts Average is greater than 6 volts.
* Module Volts Average = (MIDDLE (ModVolt1, ModVolt2, ModVolt3) + (PackVoltage/3) + (PowerElectronicsVolt/3)/3.
Action Taken When the DTC Sets
The hybrid system is disabled.
Conditions for Clearing the DTC
* Module voltage deviation from average voltage is less than the threshold.
* Pack voltage equals Valid.
* System voltage 11-18 volts
* Startup Timer is greater than 6 seconds.
* -5A is less than battery current is less than 5A.
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. Scan and record the hybrid battery voltage parameters for modules 1, 2, and 3.
2. Measure the module voltages 1, 2, and 3, DTC and compare it to the parameter scanned values in step 1. Refer to Hybrid Battery Service Disconnect/Connect ().
• If the module with the DTC has greater than 1 volt measured difference from the other 2 modules, replace the battery pack.
3. Disconnect harness connector X1 from the BECM.
4. 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.
5. If all circuits test normal, replace the BECM.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Generator Battery Temperature Sensor Wiring Harness Replacement ()
* Generator Battery Replacement ()
* Control Module References (Programming and Relearning) for BECM replacement, setup, and programming