DTC C0408
| DTC C0408 |
| Diagnostic Instructions |
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Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
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Review
Strategy Based Diagnosis
for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions
provides an overview of each diagnostic category.
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| 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 rear 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 modulated signal (PWM-signal). The solenoid valve controls the hydraulic pressure to the differential brake's clutch pack. 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
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The ignition is ON.
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Vehicle is equipped with electronic limited slip differential.
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The test runs during start up of the rear differential clutch control module.
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C0408 04
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The ignition is ON.
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Vehicle is equipped with electronic limited slip differential.
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The test runs with a frequency of 200 Hz.
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C0408 61
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Vehicle is equipped with electronic limited slip differential.
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Engine running.
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The test is run when 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).
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| Conditions for Setting the DTC |
C0408 02
Voltage is applied to the rear 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.C0408 42 and C0408 43
The rear differential clutch solenoid valve calibration values stored in the rear differential clutch control module EEPROM are invalid or out of range.C0408 4B
There are no rear differential clutch solenoid valve calibration values stored in the differential clutch control module EEPROM.C0408 61
An error is detected if the rear 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:
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All-wheel drive (AWD) is disabled
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Service Rear Axle is displayed on the driver information center.
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| Conditions for Clearing the DTC |
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The condition for setting the DTC is no longer present.
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The DTC is not detected in 40 consecutive ignition cycles.
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| Diagnostic Aids |
The rear 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
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Circuit Testing
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Connector Repairs
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Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs
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Scan Tool Reference
Control Module References for scan tool information
| Circuit/System Verification |
| 1. |
Engine running and vehicle stationary.
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| 2. |
Check using a scan tool that the rear clutch status parameter indicates Temporarily limited.
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| 3. |
If the parameter does not show Temporarily limited
See Circuit/System test. |
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| 4. |
If the parameter shows Temporarily limited
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Everything is OK.
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| Circuit/System test |
| Important | ||
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Q48 solenoid valve for the rear axle clutch is calibrated with and is part of K47 rear differential clutch control module. Both components must be replaced as a matched set. |
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C0408 02, C0408 04, C0408 42, C0408 43, or C0408 4B
| 1. |
Ignition OFF, disconnect X2 wiring harness on K47 rear differential clutch control module and cable wiring at Q49 rear differential clutch, solenoid valve.
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| 2. |
Test for less than 2 Ω in the low reference circuit end to end.
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| 3. |
If more then 2 Ω
Replace M32 pump, differential clutch/wiring harness |
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If less than 2 Ω
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| 5. |
Test for less than 2 Ω from the control circuit end to end.
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| 6. |
If more then 2 Ω
Replace M32 pump, differential clutch. |
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| 7. |
If less than 2 Ω
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| 8. |
Test for infinite resistance between the control circuit terminal and ground.
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| 9. |
If less than infinite resistance
Replace M32 pump, differential clutch. |
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| 10. |
If infinite resistance
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| 11. |
Test for 2-4 Ω between the control circuit terminal and the low reference circuit for Q49 rear differential clutch, solenoid valve.
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| 12. |
If not between 2-4 Ω
Replace Q49 rear differential clutch, solenoid valve. |
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If between 2-4 Ω
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| 14. |
Replace K47 rear differential clutch control module and Q48 solenoid valve for the rear drive clutch.
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C0408 61
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Replace Q49 rear differential clutch, solenoid valve.
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| 2. |
Ignition ON.
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| 3. |
Check that DTC C0408 61 is not set.
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| 4. |
If the DTC is set:
Replace K47 rear differential clutch control module and Q48 solenoid valve for the rear drive clutch |
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If the DTC is not set:
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Everything is OK
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| Component test |
Static test
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Test for 2-4 Ω between the control circuit and the low reference circuit for Q49 rear differential clutch, solenoid valve.
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If not between 2-4 Ω
Replace Q49 rear differential clutch, solenoid valve. |
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| 3. |
If between 2-4 Ω
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| 4. |
Everything is OK
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| Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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Limited Slip Differential Clutch Valve Replacement
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Differential Clutch Pump Replacement
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Control Module References
for rear differential clutch control module replacement, setup, and programming
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