P1A08

DTC P1A04, P1A05, P1A06, or P1A08

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 P1A04
- Battery Energy Control Module Programming Read Only Memory (ROM)

DTC P1A05
- Battery Energy Control Module Random Access Memory (RAM)

DTC P1A06
- Battery Energy Control Module Read Only Memory (ROM)

DTC P1A08
- Battery Energy Control Module Stack Overrun




Circuit/System Description

The battery energy control module (BECM) monitors to detect an RAM, ROM, EPROM or controller stack over run. If a fault is detected, the appropriate DTC will set.


Conditions for Running the DTC

The engine is running.


Conditions for Setting the DTC

P1A04, P1A06

Checksum does not match.

P1A05

Error during write to a location in RAM.

P1A08

Number of Over Runs is greater than 0.


Action Taken When the DTC Sets

Hybrid system is disabled.


Conditions for Clearing the DTC

P1A04

State = System Powerup.

P1A05, P1A06, P1A08

State = Run or Service or Powerdown or Powerup.


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


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.


1. Inspect for poor 12 volt and ground connections at the 12 volt vehicle body harness at the BECM.
2. If DTC is history, review the vehicle service history, to verify if the vehicle has been serviced for low battery concern in the past.

• If the service history did not indicate the above concern clear codes.

3. If DTC resets as 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