GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions 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

Description and Operation

Starter/Generator Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

  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 after completing the diagnostic procedure.

Generator with Starter Replacement