GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2007 🢒 VUE - AWD 🢒 DTC 🢒 DTC P1A6F

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 P1A6F: Starter/Generator System No Crank at Restart

Circuit/System Description

The starter/generator control module (SGCM) monitors to determine performance of the motor generator unit (MGU).

The AutoStop ready indication will be a DIC message that indicates the following two states:

    • AUTOSTOP AVAL (AutoStop Available)
    • AUTOSTOP UNAVAIL (AutoStop Unavailable)

The engine control module (ECM) will send an AutoStop state message to the body control module (BCM). The BCM will transmit the AutoStop state message to the instrument panel cluster (IPC). If all of the following conditions are true the indicated state will be Avail, otherwise the state will be Unavail:

    • Vehicle speed of 4 mph exceeded (initially)
    • Ambient temperature above -15°C (5°F)
    • Hybrid and powertrain components temperatures in hybrid operational ranges
       - Hybrid battery temperature is greater than 10°C (50°F) (approximate) and less than 50°C (122°F).
       - Transmission fluid temperature is greater than 35°C (95°F) (ambient temperature less than 10°C (50°F).
       - Transmission fluid temperature is greater than 20°C (68°F) (ambient temperature greater than 10°C ( 50°F).
       - Transmission fluid temperature is less than 110°C (230°F).
       - Engine coolant temperature is greater than 80°C (176°F) (ambient temperature less than 10°C ( 50°F).
       - Engine coolant temperature is greater than 47°C (176°F) (ambient temperature greater than 10°C ( 50°F)
       - Engine coolant is less than 121°C (250°F)
    • Vehicle in Drive (No autostops in I, L or Reverse)
    • HVAC compressor system request Engine ON = False
    • Grade less than 18 percent
    • Sufficient brake vacuum (20 kPa)
    • SOC is greater than required for AutoStop (70 percent).
    • Battery discharge power capability is greater than minimum required for AutoStart (6200 watts).
    • Acceptable 12 volt battery status (voltage, current, temperature)
    • No wheel slip (ABS or Traction Control) active
    • EVPR not running small leak test
    • Hood is closed.
    • Default action 1, 2, 3, or 4 not active

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

The hybrid restart DTC will set when the following occurs:

    • After initial stop, release of the brake pedal does not initiate a restart. At this time the 12-volt system will automatically start the vehicle.
    •  After the next stop, if the engine will not turn off and then restart when the brake pedal is pressed and released, this will set DTC P1A6F. If this all happens again after the next ignition cycle, the MIL will light.

Action Taken When the DTC Sets

Hybrid system is disabled.

Conditions for Clearing the DTC

The hybrid restart failed diagnostic is enabled under the following conditions:

    • Diagnostic system has not been disabled.
    • Calibration to run this application is True.
    • There are no belt slip faults.
    • Ignition switch in Run/Crank position
    • There are no MGU torque delivered faults.
    • Fuel level is above 10 percent.

Diagnostic Aids

The scan tool ECM output control Starter Enable will override most of the conditions that are normally required to allow autostart. Although the vehicle may be started, there could still be conditions that are not allowing the vehicle to autostart when it is being operated under normal conditions. If unable to autostart, verification of the enabling criteria in Circuit/System Description is required to find possible criteria that is not enabling autostart.

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 Output Controls
    •  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.

Caution: Refer to Road Test Caution in the Preface section.

  1. Use scan tool to verify if other DTCs are set.
    2. ⇒If any other DTC is set, perform that diagnostic first.
  2. Use scan tool ECM output control Starter Enable command to enable an autostart.
    3. ⇒If engine starts, road test the vehicle to confirm that the autostart is operating. Refer to Diagnostic Aids.
  3. Gain access to the following wiring connections:
    4. • Starter/generator control module (SGCM) 36 volt and 3 phase connections. Refer to Generator Control Module Replacement .
    • Motor generator unit (MGU) 3 phase cable connections. Refer to Generator with Starter Replacement .
  4. Verify the above listed connections are within specifications. Refer to Fastener Tightening Specifications .
    5. ⇒If all connections are within specifications, replace the MGU.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Generator with Starter Replacement