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 Descriptors

DTC C0393 06:  Rear Axle Coupling Solenoid Control Circuit

DTC C0393 0B:  Rear Axle Coupling Solenoid Control Circuit Current Above Threshold

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

High Coupling Solenoid Control Circuit

C0393 06

C0393 06

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Low Coupling Solenoid Control Circuit

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C0393 0B

Circuit/System Description

The Coupling Control Module (CCM) provides a power and ground circuits to the coupling solenoid. The coupling solenoid receives current from the CCM and converts that into torque through the clutch to the rear tires.

Conditions for Running the DTC

    • The ignition is ON.
    • Ignition voltage is greater than 9 volts.

Conditions for Setting the DTC

    • An open is detected on the high or low coupling solenoid circuits.
    • A short to ground is detected on the high coupling solenoid circuit.
    • An over current is detected on the Solenoid circuit.

Action Taken When the DTC Sets

One or more of the following actions may occur:

    • All Wheel Drive Off (AWD Disabled).
    • Service All Wheel Drive (Service AWD).

Conditions for Clearing the DTC

    • The condition for the DTC is no longer present.
    • The DTC is not detected in 100 consecutive drive cycles.

Reference Information

Schematic Reference

    •  Data Communication Schematics
    •  Transfer Case Control Schematics

Connector End View Reference

Component 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 for CCM

Circuit/System Verification

DTC C0393 will set as result of CCM Solenoid or circuit failure, test for power and ground circuits to the CCM.

Repair the power or ground circuits.

Circuit/System Testing

Important: It is recommend that Component Testing is performed before Circuit Testing when diagnosing the power vacuum booster Solenoid.

  1. Ignition OFF, disconnect the 5-way harness connector at the CCM.
  2. Test for less than 1.0 ohm between the ground circuit terminal and ground.
  3. If greater than 1.0 ohm, test the ground circuit for an open/high resistance.
  4. Connect a test lamp between the Battery circuit terminal and the ground circuit terminal.
  5. Ignition On engine Off. The test lamp should turn ON.
  6. If the test lamp is always ON, test the CCM circuits for an open or short to ground. If the circuit tests normal, replace the coupling control module (CCM).
    If the test lamp is always OFF, test the Battery circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the coupling solenoid.

Repair Instructions

Perform the Diagnostic System Check - Vehicle after completing the diagnostic procedure.

    •  Control Module References for CCM replacement, setup, and programming
    •  Power Vacuum Brake Booster Replacement