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DTC C0408

DTC C0408

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 C0408 02

Rear Axle Coupling Solenoid Valve Short to Ground

DTC C0408 04

Rear Axle Coupling Solenoid Valve Open

DTC C0408 42

Rear Axle Coupling Solenoid Valve Calibration Not Programmed

DTC C0408 43

Rear Axle Coupling Solenoid Valve EEPROM Incorrect Programming

DTC C0408 4B

Rear Axle Coupling Solenoid Valve Calibration Not Learned

DTC C0408 61

Rear Axle Coupling Solenoid Valve Stuck

Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
Control

C0393 0B, C0408 02

C0408 04

-

C0408 61

Low Reference

-

C0408 04

-

-



Circuit/System Description

The limited slip differential clutch solenoid valve is mounted on the rear of the differential housing. The rear differential clutch control module supplies battery voltage to the control circuit and ground to the low reference circuit of the solenoid valve. The solenoid valve is controlled by a pulse width modulation (PWM) signal. The solenoid valve controls the hydraulic pressure to the clutch package of the limited slip differential. The locking level of the limited slip differential depends on the engagement of the clutch package.

Conditions for Running the DTC


C0408 02, C0408 42, C0408 43 and C0408 4B

• The ignition is ON.

• Vehicle is equipped with electronic limited slip differential.

• The test runs during start up of the rear differential clutch control module.



C0408 04

• The ignition is ON.

• Vehicle is equipped with electronic limited slip differential.

• The test runs with a frequency of 200 Hz.



C0408 61

• Vehicle is equipped with electronic limited slip differential.

• Engine running.

• Testing is performed when the requested torque is less than 25 Nm (18 lb ft) and the calculated temperature is in the range of 0-120°C (32-248°F).


Conditions for Setting the DTC

C0408 02

Voltage is applied to the limited slip differential clutch solenoid valve. An error is detected if the current is greater than the current which corresponds to less than 2.1 Ω resistance in the solenoid valve.

C0408 04

The measured current deviates from the nominal value with more than 200 mA for more than 100 ms.

C0402 42 and C0402 43

The limited slip differential clutch solenoid valve calibration values stored in the rear differential clutch control module EEPROM are invalid or out of range.

C0402 4B

There are no limited slip differential clutch solenoid valve calibration values stored in the differential clutch control module EEPROM.

C0408 61

An error is detected if the limited slip differential clutch solenoid valve is not engaging adequately over a predetermined test sequence.

Action Taken When the DTC Sets

One or more of the following actions may occur:


• All-wheel drive (AWD) is disabled

• Service Rear Axle is displayed on the driver information center.


Conditions for Clearing the DTC


• The condition for setting the DTC is no longer present.

• The DTC is not detected in 40 consecutive ignition cycles.


Diagnostic Aids

The limited slip differential clutch solenoid valve harness and differential clutch pump harness are all one assembly as part of the differential clutch pump. These harnesses should not be repaired and should be replaced if a wiring condition exists.

Reference Information

Schematic Reference

Rear Axle Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Rear Drive Axle Description and Operation

Electrical Information Reference


• Circuit Testing

• Connector Repairs

• Testing for Intermittent Conditions and Poor Connections

• Wiring Repairs


Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Engine running, observe the scan tool Rear Drive Clutch Status parameter. The scan tool should display TEMPORARILY LIMITED when stationary.

Circuit/System Testing

Important

The torque transfer device solenoid valve is calibrated with and is part of the rear differential clutch control module. Both components must be replaced as a matched set.



1. Ignition OFF, disconnect the X2 harness connector at the K47 Rear Differential Clutch Control Module.

2. Test for a infinite resistance between the control circuit terminal C and ground.

3. If not the specified value, test the control circuit for a short to ground. If there is a short circuit to ground, replace the differential pump/wiring assembly M32. If the circuit test is normal, replace the solenoid valve of the rear axle clutch Q49.

4. Test for 2-4 Ω between the control circuit terminal C and the ground reference circuit terminal D.

5. If not within the specified range, replace the Q49 Rear Axle Coupling Solenoid Valve.

6. Replace the K47 Rear Differential Clutch Control Module.



C0408 61

1. Replace the Q49 Rear Axle Coupling Solenoid Valve.

2. Ignition ON, verify the DTC does not reset.

3. If the DTC resets, replace the K47 Rear Differential Clutch Control Module.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


• Limited Slip Differential Clutch Valve Replacement

• Differential Clutch Pump Replacement

• Control Module References for rear differential clutch control module replacement, setup, and programming