GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2009 🢒 CTS 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC C0399

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 C0399 01: Clutch Coil Circuit Malfunction Short to Battery

DTC C0399 02: Clutch Coil Circuit Malfunction Short to Ground

DTC C0399 04: Clutch Coil Circuit Malfunction Open Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Battery

Signal Invalid

Clutch Coil Control

C0399 02

C0399 04

C0399 01

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Clutch Coil Return

C0399 02

C0399 04

C0399 01

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Circuit/System Description

The transfer case normally operates in 2WD mode. When all wheel drive (AWD) is requested, the transfer case control module (TCCM) sends 12 volts to the transfer case clutch coil (TCCC) via the clutch coil control circuit. This engages the transfer case clutch assembly through a ball and cam apply system. The TCCC is controlled by a high and low side driver. Both circuits must be activated to engage the system.

Conditions for Running the DTC
    • The ignition is ON.
    • System voltage is between 9 and 16 volts.

Conditions for Setting the DTC

The voltage seen by the transfer case control module is below 0.30 volts or above 0.70 volts for more than 5 seconds.

Action Taken When the DTC Sets
    • The vehicle will be in 2WD mode while the fault is present.
    • The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.

Conditions for Clearing the DTC
    • The TCCM clears the DTC if the condition for setting the DTC is not currently present.
    • A history DTC clears after 40 consecutive warm up cycles without a fault present.
    • All DTCs can be cleared using a scan tool.
    • Clearing DTCs will also clear failure records.

Diagnostic Aids
    • Check failure records for further information on the conditions present when this DTC set.
    • Make sure system voltage is above 10.5 volts as Special Functions will not work correctly if the system is below this voltage.
    • The TCCM comes preprogrammed and is not flashable.

Reference Information

Schematic Reference

All-Wheel Drive 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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information.

Special Tools

J 35616 GM-Approved Terminal Test Kit

Circuit/System Testing
  1. Ignition OFF, disconnect the X1 connector at the TCCM. Test terminals 4 and 5 X1, harness side, for proper pin retention using J 35616-2A probe . Refer to Connector Repairs. If both terminals test normal, reconnect the X1 connector at the TCCM.

    2. Note: When test probing terminals, it is imperative to use the proper test probe from the most current version of the J 35616 test kit . Using the J 35616-35 probe will deform the terminals in the TCCC connector.

  2. Disconnect the X1 connector at the TCCC. Test terminals A and B X1, harness side, for proper pin retention using J 35616-4A. Refer to Connector Repairs.
  3. Ignition on. Using J 35616-4A probe , connect a DMM between the clutch coil control circuit, pin A X1 TCCC, harness side, and a good ground. Using the scan tool special functions, command the clutch control ON. The DMM should indicate battery voltage.
    4. ⇒If the DMM indicates less than battery voltage, test the clutch coil control circuit for an open, high resistance or short to ground. If the circuit tests normal, replace the TCCM.

    Important: There will be a diagnostic voltage of 2-4 volts present at all times, this does not indicate a short to voltage

  4. Using the scan tool special functions command the clutch control OFF. The DMM should indicate 2-4 volts.
    5. ⇒If the DMM indicates greater than 2-4 volts when it is commanded OFF, test the clutch coil control circuit for a short to voltage. If the circuit tests normal, replace the TCCM.
  5. Using J 35616-4A probe , connect a DMM between the clutch coil return circuit, pin B X1 TCCC harness side, and a good ground. Put the DMM on the audible selection for testing resistance. Using the scan tool special functions, command the clutch return circuit ON. The DMM should indicate continuity.
    6. ⇒If the DMM did not indicate continuity, test the clutch coil return circuit for an open, high resistance or a short to voltage. If the circuit tests normal, replace the TCCM.
  6. Using the scan tool special functions, command the clutch return circuit OFF. The DMM should NOT indicate continuity.
    7. ⇒If the DMM indicates continuity, test the clutch coil return circuit for a short to ground. If the circuit tests normal, replace the TCCM.
  7. Using J 35616-5 probe , test for 2-5 ohms of resistance between TCCC, pins A and B X1 TCCC.
    8. ⇒If the resistance is not within the specified range, replace the transfer case. Refer to Transfer Case Assembly Replacement.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Control Module References for TCCM replacement, setup, and programming.
    •  Transfer Case Assembly Replacement