GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2007 🢒 VUE - AWD 🢒 DTC 🢒 DTC P0A38 or P0A39

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 Descriptors

DTC P0A38: Starter/Generator Temperature Sensor Circuit Low Voltage

DTC P0A39: Starter/Generator Temperature Sensor Circuit High Voltage

Circuit/System Description

The starter/generator control module (SGCM) monitors to detect if the motor generator temperature sensor is shorted to ground, shorted to voltage or open.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

P0A38

Sensor output voltage less than 0.2 volt for 1 second

P0A39

Sensor output voltage greater than 3.95 volts for 1 second

Action Taken When the DTC Sets

P0A38, P0A39

50 percent maximum torque limit

Conditions for Clearing the DTC

P0A38, P0A39

Normal range for 10 seconds

Diagnostic Aids

P0A38

Possible temperature sensor short to ground.

P0A39

Possible temperature sensor short to voltage or open.

Reference Information

Schematic Reference

Hybrid Controls Schematics

Connector End View Reference

Hybrid Controls Connector End Views

Electrical Information Reference

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

Scan Tool Reference

Scan Tool Data List

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. Disconnect harness connector C2 from the SGCM. Refer to Generator Control Module Replacement .
  2. Using the appropriate test adapters, test for 120 - 125 kohms resistance between terminals 2 and 14 at room temperature.
    3. ⇒If within specified range, replace the SGCM.
  3. Disconnect the 7 pin C1 connector at the MGU. Refer to Generator with Starter Replacement .
  4. Test for less than 1 ohm between SGCM connector harness terminal 2 and the MGU C1 connector harness terminal G.
    5. ⇒If greater than the specified value, repair the open/high resistance.
  5. Test for less than 1 ohm between SGCM connector harness terminal 14 and the MGU C1 connector harness terminal F.
    6. ⇒If greater than the specified value, repair the open/high resistance.
  6. If both circuits test normal, replace the MGU.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Control Module References for SGCM replacement, setup and programming
    •  Generator with Starter Replacement for MGU replacement