C0397
DTC C0397
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC C0397 64
- Transfer Case Clutch Performance Actuator Slipping
Diagnostic Fault Information
Circuit/System Description
In 4WD Auto mode, the transfer case shift control module (TCCM) monitors the front and rear wheel speed sensors for slip. If the TCCM detects slip, and is unable to correct for a difference between the front and rear speed sensors, it will command the transfer case to apply the clutch. In addition, the TCCM tests for clutch pack wear by performing a high side kiss point check at power down and comparing it to the incremental position sensor reading.
Conditions for Running the DTC
* Ignition ON.
* System voltage 10.5-8 V.
Conditions for Setting the DTC
The transfer case is unable to correct for slip.
Action Taken When the DTC Sets
* Shifting is still possible but in a reduced capacity which may cause undesirable slip correction events.
* The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.
Conditions for Clearing the DTC
* The TCCM clears the DTC once the condition for setting the DTC no longer exists.
* A history DTC clears after 40 consecutive warm up cycles without a fault present.
* History DTCs can be cleared using a scan tool.
Diagnostic Aids
Faulty wheel speed sensors can cause this DTC to set. When driving at a steady speed, the scan tool should display the same values for the following data parameters in the electronic brake control module (EBCM):
* Left and right front wheel speed sensors
* Left and right rear wheel speed sensors
Reference Information
Schematic Reference
Transfer Case Control Schematics (MP 3023/3024-NQH - Transfer Case)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Control Module References (Control Module References) for scan tool information.
Circuit/System Verification
1. Ignition ON, engine OFF.
2. Install a scan tool.
3. Ensure no other ECBM or TCCM codes are set.
• If any other EBCM or TCCM DTC's are set, diagnose them first.
Circuit/System Testing
1. Install scan tool.
2. Wheel speed sensors - Take the vehicle on a short test drive on a smooth and level road. Using the Data Display function of the ECBM feature of the scan tool, when at a steady speed verify that the front and rear wheel speeds sensor displays do not vary or become intermittent.
• If while driving at a steady speed the RPM values vary or become intermittent, check the EBCM for wheel speed DTC's. Wheel speed DTC diagnostics are in antilock brake systems.
3. Transfer case clutch integrity - Shift the vehicle into 4WD HI and take it for a test drive. Clear the DTC if possible. Monitor front and rear wheel speeds using the EBCM data display. Under heavy acceleration the front and rear wheel speeds should be similar.
• If the front wheel speeds are much lower, this indicates a weak clutch and a transfer case disassembly and inspection will be required. Refer to Transfer Case Disassemble (Transfer Case Disassemble).
4. Transfer case encoder motor brake - Using a scan tool clear DTC's. Shift the vehicle to 2WD HI. Monitor the Transfer Case Motor Amperage parameter in the Data Display feature of the scan tool. Using the transfer case shift control switch, command the transfer case to the 4WD HI mode. The transfer case motor amperage should increase while the motor is shifting, and then return to 0 amps within 5 seconds or less.
• If the amperage stays high longer than 5 seconds, this indicates the brake is not holding. Replace the transfer case motor.
5. Mechanical binding -
1. Engage parking brake.
2. Block rear wheels.
3. Lift front wheels.
4. Key ON, engine OFF. Install scan tool.
5. Transfer case in 2WD HI. Transmission in Neutral.
6. Using the Special Functions capability of the scan tool, engage the front axle. While holding one front tire stationary, spin the other tire. The front propshaft should turn.
• If the front propshaft does not turn, inspect the front axle clutch fork for mechanical binding.
6. If all prior evaluations test normal, reprogram the TCCM and perform the ATC Motor Learn procedure in the Special Functions feature of the scan tool or the Transfer Case High/Low Clutch Reset (Transfer Case High/Low Clutch Reset) procedure in the service manual.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Control Module References (Control Module References) for TCCM replacement, setup, and programming
* Transfer Case High/Low Clutch Reset (Transfer Case High/Low Clutch Reset) for Motor Learn Procedure
* Four-Wheel Drive Does Not Engage (Four-Wheel Drive Does Not Engage)
* Two/Four Wheel Drive Shift Components Cleaning and Inspection (Two/Four Wheel Drive Shift Components Cleaning and Inspection)
* Front Output Shaft and Input Shaft Cleaning and Inspection (Front Output Shaft and Input Shaft Cleaning and Inspection)
* Drive Chain, Drive Sprocket, and Driven Sprocket Cleaning and Inspection (Drive Chain, Drive Sprocket, and Driven Sprocket Cleaning and Inspection)
* High/Low Planetary Carrier Cleaning and Inspection (High/Low Planetary Carrier Cleaning and Inspection)
* High/Low Shift Components Cleaning and Inspection (High/Low Shift Components Cleaning and Inspection)
* Front Drive Axle Clutch Fork Inspection (Front Drive Axle Clutch Fork Inspection)
* Transfer Case Disassemble (Transfer Case Disassemble)
* Transfer Case Assemble (Transfer Case Assemble)
* Transfer Case Assembly Replacement (Transfer Case Assembly Replacement)