P1A27

DTC P1A26 or P1A27

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 P1A26
- Hybrid Battery 1 Voltage Low

DTC P1A27
- Hybrid Battery 1 Voltage Very Low




Circuit/System Description

The battery energy control module (BECM) monitors the hybrid battery 1 voltage to detect if the minimum voltage is less than the calibration value.


Conditions for Running the DTC

The engine is running.


Conditions for Setting the DTC

P1A26

Minimum module voltage is less than calibration value for 3 seconds.

P1A27

Minimum module voltage is less than calibration value for 40 ms.


Action Taken When the DTC Sets

The hybrid system is disabled.


Conditions for Clearing the DTC

P1A26, P1A27

System voltage 11-18 volts.


Reference Information
Schematic Reference

Hybrid Controls 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


Circuit/System Verification

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.


P1A26, P1A27

If DTC is current, replace the BECM.


Repair Instructions

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


Control Module References (Programming and Relearning)for BECM replacement, setup, and programming