P0A3B

DTC P0A3B

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 P0A3B
- Starter/Generator Overtemperature




Circuit/System Description

The starter/generator control module (SGCM) monitors the motor generator unit (MGU) temperature sensor for an overtemperature condition.


Conditions for Running the DTC

The engine is running.


Conditions for Setting the DTC

MGU temperature is greater than 205°C (401°F) for 1 second.


Action Taken When the DTC Sets

Stop PWM (MGU shutdown)


Conditions for Clearing the DTC

MGU temperature is less than 150°C (212°F) for 3 seconds.


Diagnostic Aids

Possible MGU fan failure caused by obstructions, blockage to the vents or damaged fan.


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 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.


1. Perform the Hybrid Battery Service Disconnect/Connect ().
2. Inspect the connection of 3 phase cables for the proper torque. Refer to Fastener Tightening Specifications ().


If the 3 phase cables are within torque specifications, replace the MGU.



Repair Instructions

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


Generator with Starter Replacement () for MGU replacement