Diagnostic Instructions

DTC Descriptor

DTC C0408 02: Rear Axle Coupling Solenoid Valve Short to Ground

DTC C0408 04: Rear Axle Coupling Solenoid Valve Open

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	C0408 02	C0408 04	C0408 04	C0408 04
Low Reference	C0408 02	C0408 04	C0408 04	C0408 04

Component	Condition	DTCs
Solenoid Valve	Mechanically Stuck	C0408 61

Circuit/System Description

The rear axle coupling solenoid valve is installed at the rear halfshaft leading to the rear left wheel. 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 04

C0408 61

Conditions for Setting the DTC

C0408 02

A test voltage is applied to the rear axle coupling solenoid valve. An error is detected if the resultant current is greater than the current which corresponds to less than 2.1 Ω resistance in the solenoid valve.

C0408 04

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

C0408 61

The valve is subjected to a current spike that should move the needle physically. An error is detected if the solenoid valve is not moving fast enough and an error counter reaches a threshold.

Action Taken When the DTC Sets

One or more of the following actions may occur:

Conditions for Clearing the DTC

Reference Information

Schematic Reference

Rear Axle Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

All-Wheel Drive Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for diagnostic tester information

Circuit/System Verification

Engine running, observe the scan tool Rear Drive Clutch Status parameter. The reading should be NORMAL when stationary.

Circuit/System Testing

C0408 02 and C0408 04

1. Ignition OFF, inspect for signs of damage of the wire, the solenoid or the housing.

⇒	If a damage is visible, replace the appropriate component.

2. Disconnect the X2 harness connector at the K47 Rear Differential Clutch Control Module.
3. Test for an infinite resistance between the control circuit terminal W3 at the Q49 Rear Axle Coupling Solenoid Valve and ground.

⇒	If not within the specified range, test the control circuit and the low reference circuit for a short to ground. If the circuits test normal, replace the Q49 Rear Axle Coupling Solenoid Valve.

4. If the circuits test normal, replace the K47 Rear Differential Clutch Control Module.

C0408 61

1. Ignition OFF, inspect for signs of damage of the housing.

⇒	If a damage is visible, replace the appropriate component.

2. Ignition OFF, replace the Q49 Rear Axle Coupling Solenoid Valve.
3. Ignition ON, verify the DTC does not reset.

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.