Rear Drive Axle Buick LaCrosse II

Fastener Tightening Specifications

Fastener Tightening Specifications

Lubrication Specifications

Lubrication Specifications

Adhesives, Fluids, Lubricants, and Sealers

Adhesives, Fluids, Lubricants, and Sealers

Scheme 1

Diagnostic Code Index

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

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 modulation (PWM) signal. The solenoid valve controls the hydraulic pressure to the clutch package of the rear differential. The locking level of the limited slip differential depends on the engagement of the clutch package.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

1. The rear differential clutch control module detects a short to ground on the rear differential clutch solenoid valve control circuit.
2. The rear differential clutch control module detects a current greater than 5.7 A on the rear differential clutch solenoid valve control circuit.

Action Taken When the DTC Sets

One or more of the following actions may occur

1. All-wheel drive (AWD) is disabled.
2. Service Rear Axle is displayed on the driver information center.

Conditions for Clearing the DTC

1. The condition for setting the DTC is no longer present.
2. The DTC is not detected in 40 consecutive ignition cycles.

Diagnostic Aids

The rear differential clutch solenoid valve harness and differential clutch pump motor harness are all one assembly as part of the differential clutch pump motor. 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 - INDEX

Description and Operation

Rear Drive Axle Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Engine running and vehicle stationary.
2. Verify the scan tool Rear Differential Clutch Status parameter is Normal. If not Normal Refer to Circuit/System Testing below. If Normal
3. All OK.

Circuit/System Testing

Note. The Q48 Rear Drive Clutch Solenoid Valve is calibrated with and is part of the K47 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 and disconnect the harness connector at the Q49 Rear Differential Clutch Solenoid Valve.
2. Test for infinite resistance between the Q49 Rear Differential Clutch Solenoid Valve control circuit terminal and ground. If less than infinite resistance Test or replace the M32 Differential Clutch Pump. If infinite resistance
3. Test for 2-4 ohms between the Q49 Rear Differential Clutch Solenoid Valve control terminal and Q49 Rear Differential Clutch Solenoid Valve low reference terminal. If not between 2-4 ohms Test or replace the Q49 Rear Differential Clutch Solenoid Valve. If between 2-4 ohms
4. Replace the K47 Rear Differential Clutch Control Module and Q48 Rear Drive Clutch Solenoid Valve.

Component Testing

Static Test

1. Disconnect the Q49 Rear Differential Clutch Solenoid Valve.
2. Test for 2-4 ohms between the control terminal and low reference terminal. If not between 2-4 ohms Replace the Q49 Rear Differential Clutch Solenoid Valve. If between 2-4 ohms
3. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

1. «Limited Slip Differential Clutch Valve Replacement»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle)
2. «Differential Clutch Pump Replacement»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle)
3. «Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for rear differential clutch control module replacement, programming, and setup.

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The rear differential clutch control module monitors the amount of torque transferred through the rear axle. If there is a mechanical malfunction that inhibits the torque transfer process the module will then set DTC C039F.

The ignition is ON.

A mechanical malfunction exists that inhibits the torque transfer process.

One or more of the following actions may occur

1. All-wheel drive (AWD) is disabled.
2. Service Rear Axle is displayed on the driver information center.

1. The condition for setting the DTC is no longer present.
2. The DTC is not detected in 40 consecutive ignition cycles.

Schematic Reference

Rear Axle Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Rear Drive Axle Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Note. The Q48 Rear Drive Clutch Solenoid Valve is calibrated with and is part of the K47 Rear Differential Clutch Control Module. Both components must be replaced as a matched set.

1. Engine running and vehicle stationary.
2. Verify the scan tool Rear Drive Clutch Status parameter is Temporarily Limited. If not Temporarily Limited Verify that DTC C0402, C0403, C0406, or C0407 is not set. If any of the DTCs are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) . If none of the DTCs are set Verify there are no internal/external leaks or mechanical damage and that all differential fluid levels are at the proper levels. Refer to «Rear Axle Lubricant Level Inspection»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle) , and «Differential Clutch Oil Inspection»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle__differential-clutch-oil-inspection) . Clear DTCs and road test the vehicle. Verify that DTC C039F is not set. If the DTC is set, replace the K47 Rear Differential Clutch Control Module and Q48 Rear Drive Clutch Solenoid Valve. If the DTC is not set All OK. If Temporarily Limited
3. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

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

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The rear drive clutch solenoid valve is internal to the torque transfer device 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 torque transfer device. The locking level of the torque transfer device depends on the engagement of the clutch package.

C0402 02, C0402 42, C0402 43 and C0402 4B

1. The ignition is ON.
2. The circuits are tested during start up of the rear differential clutch control module.

C0402 04

The ignition is ON.

C0402 61

1. Engine running.
2. When requested torque is less than 25 Nm (18 lb ft) and the calculated temperature is in the range of 0-90°C (32-194°F).

C0402 02

Voltage is applied to the rear drive clutch solenoid valve. An error is detected if the current is greater than the current which corresponds to less than 2 ohms resistance in the solenoid valve.

C0402 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 solenoid valve calibration values stored in the rear differential clutch control module EEPROM are invalid or out of range.

C0402 4B

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

C0402 61

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

C0402 02, C0402 04 and C0402 61

One or more of the following actions may occur

1. All-wheel drive (AWD) is disabled.
2. Service Rear Axle is displayed on the driver information center.

C0402 42, C0402 43 and C0402 4B

An error record is stored in the rear differential clutch control module. No action will be performed.

1. The condition for setting the DTC is no longer present.
2. The DTC is not detected in 40 consecutive ignition cycles.

Schematic Reference

Rear Axle Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Rear Drive Axle Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Note. The Q48 Rear Drive Clutch Solenoid Valve is calibrated with and is part of the K47 Rear Differential Clutch Control Module. Both components must be replaced as a matched set.

1. Engine running and vehicle stationary.
2. Verify the scan tool Rear Drive Clutch Status parameter is Temporarily Limited. If not Temporarily Limited Verify DTC C0402 is not set. If the DTC is set, replace the K47 Rear Differential Clutch Control Module and Q48 Rear Drive Clutch Solenoid Valve. If the DTC is not set All OK. If Temporarily Limited
3. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

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

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The differential clutch pump delivers hydraulic oil pressure to the rear drive clutch solenoid valve and the rear differential clutch solenoid valve. The pump is mounted to the torque transfer device housing. The pressure of the system is calculated by the rear differential clutch control module which monitors the differential clutch pump current levels. When the pressure reaches approximately 3200 kPa (464 psi), the rear differential clutch control module determines that the system pressure has been obtained and deactivates the differential clutch pump. If a voltage is detected after a predetermined time limit when the pump has been deactivated an error is detected. This condition indicates the pump is spinning backwards.

1. The ignition is ON.
2. Operating temperature range 0-80°C (0-176°F).

The rear differential clutch control module detects voltage on the differential clutch pump control circuit 20 seconds after the pump has been deactivated indicating the pump is spinning in reverse direction.

One or more of the following actions may occur

1. All-wheel drive (AWD) is disabled
2. Service Rear Axle is displayed on the driver information center.

1. The condition for setting the DTC is no longer present.
2. The DTC is not detected in 40 consecutive ignition cycles.

Schematic Reference

Rear Axle Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Rear Drive Axle Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Engine running and vehicle stationary.
2. Verify the scan tool Rear Drive Clutch Status parameter is Temporarily Limited. If not Temporarily Limited Replace the oil filter in the torque transfer device housing. If Temporarily Limited
3. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

Differential Clutch Oil Filter Replacement

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The rear drive clutch solenoid valve is internal to the torque transfer device 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 torque transfer device. The locking level of the torque transfer device depends on the engagement of the clutch package.

The ignition is ON.

1. The rear differential clutch control module detects a short to ground on the control circuit of the rear drive clutch solenoid valve.
2. The rear differential clutch control module detects a current more than 11 A on the control circuit of the rear drive clutch solenoid valve.

One or more of the following actions may occur

1. All-wheel drive (AWD) is disabled.
2. Service Rear Axle is displayed on the driver information center.

1. The condition for setting the DTC is no longer present.
2. The DTC is not detected in 40 consecutive ignition cycles.

Schematic Reference

Rear Axle Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Rear Drive Axle Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Note. The Q48 Rear Drive Clutch Solenoid Valve is calibrated with and is part of the K47 Rear Differential Clutch Control Module. Both components must be replaced as a matched set.

1. Engine running and vehicle stationary.
2. Verify the scan tool Rear Drive Clutch Status parameter is Temporarily Limited. If not Temporarily Limited Verify DTC C0406 is not set. If the DTC is set, replace the K47 Rear Differential Clutch Control Module and Q48 Rear Drive Clutch Solenoid Valve. If the DTC is not set All OK. If Temporarily Limited
3. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

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

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The differential clutch pump delivers hydraulic oil pressure to the rear drive clutch solenoid valve and the rear differential clutch solenoid valve. The pump is mounted to the torque transfer device housing. The pressure of the system is calculated by the rear differential clutch control module which monitors the differential clutch pump motor current levels. When the calculated pressure reaches approximately 3200 kPa (464 psi), the rear differential clutch control module determines that the system pressure has been obtained and deactivates the differential clutch pump. When the calculated pressure drops below approximately 2700 kPa (392 psi), the rear differential clutch control module will reactivate the differential clutch pump.

1. The ignition is ON.
2. Operating temperature range 0-80°C (0-176°F).

C0407 02

The differential clutch pump current is greater than 9 A in 20 consecutive test cycles. The current will be retested every 30 seconds.

C0407 04

The differential clutch pump current is less than 0.3 A for 30 seconds.

C0407 0B

The differential clutch pump current is greater than 7 A for greater than 2 seconds in 10 consecutive test cycles.

C0407 64

The differential clutch pump current is below a threshold at the end of a pump activation cycle in 30 consecutive test cycles. The measured current is less than 1.5 A from the threshold. The threshold is temperature dependent.

1. All-wheel drive (AWD) is disabled
2. Service Rear Axle is displayed on the driver information center.

1. The condition for setting the DTC is no longer present.
2. The DTC is not detected in 40 consecutive ignition cycles.

Extreme cold Temperatures, below -18°C (0°F), can cause a DTC C0407 to set. If DTC C0407 sets under these conditions it may be caused by the fluid viscosity and not an electrical malfunction. Before performing the diagnostics allow the differential clutch fluid temperature to rise above 0°C (32°F). If the DTC is no longer set or set in history when above 0°C (32°F) the issue was caused by the fluid viscosity and does not require any electrical repairs. Check for rear differential clutch control module calibration updates.

Schematic Reference

Rear Axle Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Rear Drive Axle Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Verify that DTC C0407 with symptom byte 02, 04 or 0B is not set. If DTC C0407 with symptom byte 02, 04 or 0B is set Refer to Circuit/System Testing below. If DTC C0407 with symptom byte 02, 04 or 0B is not set
2. Verify the rear axle fluid level is correct. Refer to «Rear Axle Lubricant Level Inspection»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle) . If the rear axle fluid is below specifications Inspect for fluid leaks and fill as required. If the rear axle fluid is above specifications Verify the differential clutch fluid level is correct. Refer to «Differential Clutch Oil Inspection»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle__differential-clutch-oil-inspection) . If the differential clutch fluid is below specifications, replace the limited slip differential clutch. If the differential clutch fluid is above specifications, lower the rear differential clutch fluid to the correct level. If the differential clutch fluid level is correct. Lower the rear axle fluid to the correct level. If the rear axle lubricant level is correct
3. Verify the differential clutch fluid level is correct. Refer to «Differential Clutch Oil Inspection»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle__differential-clutch-oil-inspection) . If the differential clutch fluid is below specifications Inspect for fluid leaks and fill as required, refer to «Differential Clutch Oil Inspection»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle__differential-clutch-oil-inspection) . If the differential clutch fluid is above specifications Lower the differential clutch fluid to the correct level. If the differential clutch lubricant level is correct
4. Verify that DTC C0407 with symptom byte 64 is not set as current. If DTC C0407 with symptom byte 64 is set as current and the differential clutch fluid level is correct Refer to Circuit/System Testing below. If DTC C0407 with symptom byte 64 is not set
5. Ignition ON.
6. Verify the Rear Differential Clutch Pump Motor Current parameter is between 2.5-3.5 A when commanding the Rear Differential Clutch Pump Motor ON with a scan tool. If not between 2.5-3.5 A Verify there are no system leaks while under pump pressure. If the system is leaking repair as necessary. If system is not leaking, replace the M32 Differential Clutch Pump. If between 2.5-3.5 A
7. All OK.

Note. The Q48 Rear Drive Clutch Solenoid Valve is calibrated with and is part of the K47 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 infinite resistance between the differential clutch pump control circuit and ground. If less than infinite resistance Test or replace the M32 Differential Clutch Pump. If infinite resistance
3. Test for 1.5-20 ohms between the control circuit and the low reference circuit. If not between 1.5-20 ohms Test or replace the M32 Differential Clutch Pump. If between 1.5-20 ohms
4. Replace the K47 Rear Differential Clutch Control Module and Q48 Rear Drive Clutch Solenoid Valve.

Perform the Diagnostic Repair Verification after completing the repair.

1. «Differential Clutch Pump Replacement»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle)
2. «Limited Slip Differential Clutch Replacement»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle)
3. «Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for rear differential clutch control module replacement, programming and setup

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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 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.

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

1. The ignition is ON.
2. Vehicle is equipped with electronic limited slip differential.
3. The test runs during start up of the rear differential clutch control module.

C0408 04

1. The ignition is ON.
2. Vehicle is equipped with electronic limited slip differential.
3. The test runs with a frequency of 200 Hz.

C0408 61

1. Vehicle is equipped with electronic limited slip differential.
2. Engine running.
3. Test runs 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).

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 ohms 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.

One or more of the following actions may occur

1. All-wheel drive (AWD) is disabled
2. Service Rear Axle is displayed on the driver information center.

1. The condition for setting the DTC is no longer present.
2. The DTC is not detected in 40 consecutive ignition cycles.

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.

Schematic Reference

Rear Axle Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Rear Drive Axle Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Engine running and vehicle stationary.
2. Verify the scan tool Rear Drive Clutch Status parameter is Temporarily Limited. If not Temporarily Limited Refer to Circuit/System Testing below. If Temporarily Limited
3. All OK.

Note. The Q48 Rear Drive Clutch Solenoid Valve is calibrated with and is part of the K47 Rear Differential Clutch Control Module. Both components must be replaced as a matched set.

C0408 02, C0408 04, C0408 42, C0408 43, or C0408 4B

1. Ignition OFF, disconnect the X2 harness connector at the K47 Rear Differential Clutch Control Module and disconnect the harness connector at the Q49 Rear Differential Clutch Solenoid Valve.
2. Test for less than 2 ohms between the K47 Rear Differential Clutch Control Module low reference circuit terminal X2 and Q49 Rear Differential Clutch Solenoid Valve low reference circuit terminal. If greater than 2 ohms Replace the M32 differential clutch pump. If less than 2 ohms
3. Test for less than 2 ohms between the K47 Rear Differential Clutch Control Module control circuit terminal X2 and Q49 Rear Differential Clutch Solenoid Valve control circuit terminal. If greater than 2 ohms Replace the M32 differential clutch pump. If less than 2 ohms
4. Test for infinite resistance between the Q49 Rear Differential Clutch Solenoid Valve control circuit terminal and ground. If less than infinite resistance Replace the M32 differential clutch pump. If infinite resistance
5. Test for 2-4 ohms between the Q49 Rear Differential Clutch Solenoid Valve control terminal and Q49 Rear Differential Clutch Solenoid Valve low reference terminal. If not between 2-4 ohms Test or replace the Q49 Rear Differential Clutch Solenoid Valve. If between 2-4 ohms
6. Replace the K47 Rear Differential Clutch Control Module and Q48 Rear Drive Clutch Solenoid Valve.

C0408 61

1. Replace the Q49 Rear Differential Clutch Solenoid Valve.
2. Ignition ON.
3. Verify DTC C0408 61 is not set. If the DTC is set Replace the K47 Rear Differential Clutch Control Module and Q48 Rear Drive Clutch Solenoid Valve. If the DTC is not set
4. All OK.

Static Test

1. Disconnect the Q49 Rear Differential Clutch Solenoid Valve.
2. Test for 2-4 ohms between the control terminal and the low reference terminal. If not between 2-4 ohms Replace the Q49 Rear Differential Clutch Solenoid Valve. If between 2-4 ohms
3. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

1. «Limited Slip Differential Clutch Valve Replacement»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle)
2. «Differential Clutch Pump Replacement»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle)
3. «Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for rear differential clutch control module replacement, programming, and setup.

1. Perform the «Diagnostic System Check - Vehicle»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/buick/lacrosse/ii-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

A temperature sensor is installed on the circuit board of the rear differential clutch control module. The sensor is used for calculating the module circuit board and differential clutch fluid temperature.

1. The ignition is ON.
2. The test runs with a frequency of 50 Hz.

C0574 02

The analog-digital converter circuit is shorted to ground for more than 3 seconds.

C0574 04

The analog-digital converter circuit is open for more than 3 seconds.

C0574 13

The board temperature is greater than 115°C (239°F) for more than 3 seconds.

C0574 14

The board temperature is less than -40°C (-40°F) for more than 3 seconds.

One or more of the following actions may occur

1. All-wheel drive (AWD) is disabled.
2. Service Rear Axle is displayed on the driver information center.

C0574 02 and C0574 04

1. The condition for setting the DTC is no longer present.
2. The circuit is not tested unless the ignition is cycled.

C0574 13 and C0574 14

1. The temperature is within the limit for more than 30 s.
2. The circuit is tested with a frequency of 50 Hz.

C0574 13 and C0574 14

The DTCs C0574 13 and C0574 14 indicate that the rear differential clutch control module temperature is out of range. This is a temporary fault. The rear differential clutch control module is protected against running during critical temperatures. As soon as the temperature reaches normal values the actual DTC is cleared.

Schematic Reference

Rear Axle Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Rear Drive Axle Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON.
2. Verify the scan tool Rear Differential Clutch Control Module Temperature parameter is between -40°C (-40°F) and 115°C (239°F). If not between -40°C (-40°F) and 115°C (239°F) Refer to Circuit/System Testing below. If between -40°C (-40°F) and 115°C (239°F)
3. All OK.

Note. The Q48 Rear Drive Clutch Solenoid Valve is calibrated with and is part of the K47 Rear Differential Clutch Control Module. Both components must be replaced as a matched set.

C0574 02 and 0574 04

1. Ignition ON.
2. Verify DTC C0574 02 or 0574 04 is not set. If either DTC is set Replace the K47 Rear Differential Clutch Control Module and Q48 Rear Drive Clutch Solenoid Valve. If the DTC is not set
3. All OK.

C0574 13 and 0574 14

1. Ignition OFF, allow the housing and the K47 Rear Differential Clutch Control Module temperature to adjust to within 0-40°C (32-104°F).
2. Ignition ON.
3. Verify DTC C0574 13 or C0574 14 is not set. If either DTC is set Replace the K47 Rear Differential Clutch Control Module and Q48 Rear Drive Clutch Solenoid Valve. If the DTC is not set
4. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

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

Scheme 2

Rear Differential Clutch Control Module Replacement

Scheme 3

Rear Axle Lubricant Level Inspection

Differential Clutch Oil Inspection

1. Run the engine at idling speed for 5 minutes to distribute the fluid.
2. In park, cycle throttle to wide open throttle briefly 5 times to cycle solenoids to purge air.
3. Turn the engine off.
4. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
5. Remove the fill plug (1) and check the differential clutch fluid level.
6. Add the proper differential clutch fluid, if needed. Refer to «Adhesives, Fluids, Lubricants, and Sealers»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle__adhesives-fluids-lubricants-and-sealers) .
7. Install the fill plug (1) and tighten to 14 (10 lb ft).
8. Install the scan tool.
9. With engine running, observe the scan tool Rear Differential Clutch Pump Motor Current parameter. The parameter display should be between 2500-3500 mA when the pump is on. If the parameter is below 2500 mA, recheck the fluid level.
10. Repeat steps 1-6 to ensure the proper differential clutch fluid level.
11. Remove the supports and lower the vehicle.

Scheme 4

Differential Oil Replacement

Removal Procedure

1. Raise the vehicle and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
2. Remove the vent hose (1).
3. Remove the differential clutch cover to drain the differential clutch.
4. Remove the vent hose fitting (2) and the hose (1) from the differential clutch cover.

Installation Procedure

Note. Both the fluid level and clutch motor current parameter requirements must be met to ensure the differential is filled to specifications.

1. Install the differential clutch cover.
2. Install the differential cover bolts and tighten to 6 (53 lb in) in a star pattern and repeat this torque sequence twice to ensure proper sealing around the accumulator and the filter.
3. Fill the differential clutch with 350 ml (12 ounces) of the proper differential fluid through the vent hose fitting hole. Refer to «Adhesives, Fluids, Lubricants, and Sealers»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle__adhesives-fluids-lubricants-and-sealers) .
4. Remove the supports and lower the vehicle.
5. To stabilize the oil level, let the vehicle rest for 10 minutes with the ignition off.
6. Start the engine and allow to run for 5 minutes at idle.
7. In park, cycle the throttle to wide open briefly 5 times to cycle solenoids to purge air.
8. Shut the vehicle off.
9. Raise the vehicle.
10. Remove the differential clutch level inspection plug (1).
11. The differential clutch fluid should be level with the bottom of the differential clutch fluid level inspection plug hole.
12. If needed, install the differential clutch level inspection plug and add 50 ml (1.7 ounce) through the vent fitting hole. Repeat step 4 through 11.
13. Install the vent hose fitting (2) and tighten to 14 (10 lb ft).
14. Install then vent hose (1).
15. Lower the vehicle.
16. Install the scan tool.
17. With engine running, observe the scan tool Rear Differential Clutch Pump Motor Current parameter. The parameter display should be between 2500-3500 mA when the pump is on. If the parameter is below 2500 mA, repeat step 12.
18. If the parameter is between 2500-3500 mA, check the differential clutch is not overfilled. If the differential clutch is over filled, remove the fluid level inspection plug and allow the excess fluid to drain.

Scheme 5

Differential Carrier Bushing Replacement - Front

Scheme 6

Differential Carrier Bushing Replacement - Rear

Scheme 7

Rear Axle Shaft Seal Replacement - Left Side (Black Seal)

Scheme 8

Rear Axle Shaft Seal Replacement - Left Side (Yellow Seal)

Scheme 9

Rear Axle Shaft Seal Replacement - Right Side (Black Seal)

Scheme 10

Rear Axle Shaft Seal Replacement - Right Side (Yellow Seal)

Note. The following service procedure is also to include those vehicles with RPO G96.

Note. Note the color of the axle seal. There are two different types of axle seals, Black and Yellow. These seals are NOT interchangeable. Use the color seal that is currently equipped on the vehicle.

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/buick/lacrosse/ii-2009-2013/remont/ignition-switchsteering-lock/#general-information__lifting-and-jacking-the-vehicle) .
2. If replacing the rear differential assembly, drain the rear differential fluid. Refer to «Differential Clutch Oil Replacement»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle) , and «Differential Oil Replacement»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle) .
3. Remove the propeller shaft assembly. Refer to «Propeller Shaft Replacement»(/buick/lacrosse/ii-2009-2013/remont/driveshaft-universal-joints/#propeller-shaft) .
4. Remove the exhaust muffler assembly. Refer to «Exhaust Muffler Replacement (Single)»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system) , «Exhaust Muffler Replacement (LFX)»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system) .
5. Remove the electronic park brake control module. Refer to «Electronic Parking Brake Control Module Replacement»(/buick/lacrosse/ii-2009-2013/remont/parking-brake-system/#parking-brake-system) .
6. Remove the wheel drive shaft. Refer to «Rear Wheel Drive Shaft Replacement»(/buick/lacrosse/ii-2009-2013/remont/axle-shafts/#wheel-drive-shafts) .
7. Disconnect the electrical connectors from the rear differential assembly to the chassis.
8. Support the rear differential assembly with a hydraulic transmission jack.
9. Remove the rear differential assembly mounting bolts (1).
10. Remove the front differential mounting bolts (1).
11. Using the hydraulic jack stand, remove the rear differential assembly (1) from the vehicle.
12. Remove the rear axle seals, if needed. For the left rear axle seal, refer to «Rear Axle Shaft Seal Replacement - Left Side (Black Seal)»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle) , «Rear Axle Shaft Seal Replacement - Left Side (Yellow Seal)»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle) For the right rear axle seal, refer to «Rear Axle Shaft Seal Replacement - Right Side (Black Seal)»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle) , «Rear Axle Shaft Seal Replacement - Right Side (Yellow Seal)»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle)

1. Install the rear axle seals, if needed. For the left rear axle seal, refer to «Rear Axle Shaft Seal Replacement - Left Side (Black Seal)»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle) , «Rear Axle Shaft Seal Replacement - Left Side (Yellow Seal)»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle) For the right rear axle seal, refer to «Rear Axle Shaft Seal Replacement - Right Side (Black Seal)»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle) , «Rear Axle Shaft Seal Replacement - Right Side (Yellow Seal)»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle)
2. Using the hydraulic jack stand, position the rear differential assembly (1) in the vehicle.
3. Clean the bolts and apply thread locker on the threads. Refer to «Adhesives, Fluids, Lubricants, and Sealers»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle__adhesives-fluids-lubricants-and-sealers)
4. Install the front differential mounting bolts (1) and tighten to: First Pass: 40 (30 lb ft) Final Pass: plus 90 degrees
5. Install the rear differential assembly mounting bolts (1) and tighten to: First Pass: 40 (30 lb ft) Final Pass: plus 90 degrees
6. Remove the hydraulic jack stand.
7. Install the wheel drive shafts. Refer to «Rear Wheel Drive Shaft Replacement»(/buick/lacrosse/ii-2009-2013/remont/axle-shafts/#wheel-drive-shafts) .
8. Install the electronic park brake control module. Refer to «Electronic Parking Brake Control Module Replacement»(/buick/lacrosse/ii-2009-2013/remont/parking-brake-system/#parking-brake-system) .
9. Reconnect the electrical connectors from the rear differential assembly to the chassis.
10. Install the exhaust muffler assembly. Refer to «Exhaust Muffler Replacement (Single)»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system) , «Exhaust Muffler Replacement (LFX)»(/buick/lacrosse/ii-2009-2013/remont/exhaust/#engine-exhaust-system) .
11. Install the propeller shaft assembly. Refer to «Propeller Shaft Replacement»(/buick/lacrosse/ii-2009-2013/remont/driveshaft-universal-joints/#propeller-shaft) .
12. Check the fluid level of the rear differential assembly. Refer to «Differential Clutch Oil Inspection»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle__differential-clutch-oil-inspection) , and «Rear Axle Lubricant Level Inspection»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle) .
13. If installing a NEW rear differential assembly, fill with the proper fluid. Refer to «Differential Clutch Oil Replacement»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle) , and «Differential Oil Replacement»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle) .
14. Remove the supports and lower the vehicle.
15. Program the rear differential assembly. Refer to «Control Module References»(/buick/lacrosse/ii-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) .

Scheme 11

Propeller Shaft Flange Replacement

Scheme 12

Limited Slip Differential Clutch Pipe Connector Replacement

Scheme 13

Limited Slip Differential Clutch Low Pressure Pipe Replacement

Scheme 14

Limited Slip Differential Clutch High Pressure Pipe Replacement

Scheme 15

Limited Slip Differential Clutch Valve Replacement

Scheme 16

Limited Slip Differential Clutch Replacement

Scheme 17

Differential Seal Replacement

Scheme 18

Differential Clutch Replacement

Scheme 19

Differential Clutch Pump Replacement

Scheme 20

Differential Clutch Seal Replacement (Outer)

Scheme 21

Differential Clutch Seal Replacement (Inner)

Scheme 22

Differential Clutch Oil Filter Replacement

Limited Slip Differential Disassemble

1. Drain the oil from the limited slip differential and fit the drain plug with a new seal and tighten to 25 N.m (18.4 lb ft).
2. Remove the complete unit, differential clutch and limited slip differential. Refer to «Differential Carrier Assembly Replacement»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle)
3. Seal the drive shaft holes in the limited slip differential and clean the housing.
4. Place the unit on its side.
5. Remove the bolts (1).
6. Remove the right-hand limited slip differential housing (2).

Limited Slip Differential Assemble

1. Clean sealant from the sealing surfaces and wash with a suitable degreaser. Refer to «Adhesives, Fluids, Lubricants, and Sealers»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle__adhesives-fluids-lubricants-and-sealers)
2. Apply a bead of (1) Sealing adhesive to one sealing surface Refer to «Adhesives, Fluids, Lubricants, and Sealers»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle__adhesives-fluids-lubricants-and-sealers)
3. Fit the right-hand limited slip differential housing (2) using new bolts (1) and tighten to 45 N.m (33 lb ft).
4. Fit Complete unit, differential clutch and limited slip differential. Refer to «Differential Carrier Assembly Replacement»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle)
5. Fill the limited slip differential with oil, using a clean funnel and hose. The oil level should be below the hole. For oil type and volume refer to «Adhesives, Fluids, Lubricants, and Sealers»(/buick/lacrosse/ii-2009-2013/remont/differentials-drive-axles/#rear-drive-axle__adhesives-fluids-lubricants-and-sealers) .
6. Fit the level plug with a new sealing washer and tighten to 25 N.m (18.4 lb ft).

General

The differential carrier assembly is located in the rear subframe and the drive shafts extend from it to each respective rear wheel. The final drive gear consists of a hypoid gear and a differential. The assembly is bolted to the subframe with 4 bolts.

The splines-equipped pinion shaft for the final drive gear is directly inserted into the disc cage for the differential.

During manufacture the differential carrier assembly is filled with oil, which then does not require changing. The correct type of oil must be used without exception when filling. The incorrect type of oil may destroy the differential. The differential is fully mechanical.

Scheme 23

The differential carrier assembly housing consists of two halves, a right and left-hand half, bolted to each other with 11 bolts. Their relative position is governed by two guide pins. Housing and cover are produced from a high-pressure cast aluminum alloy. A number of reinforcement ribs are fitted in suitable locations to strengthen the housing and cover. The mating face between them is sealed using sealant.

Scheme 24

The left-hand half contains pinion, oil level plug, drain plug, air valve, bearing race for the final drive gear's left-hand bearing, stuffing box for sealing at the drive shaft lead-through. If the car is equipped with limited slip differential clutch then it is bolted to the left-hand half of the final drive gear.

Scheme 25

The right-hand half contains bearing race for the final drive gear's right-hand bearing as well as stuffing box for sealing at the drive shaft lead-through.

Scheme 26

The pinion is fitted in the final drive gear's left-hand housing and cannot be replaced. It is mounted with two conical roller bearings, fitted towards each other. The bearing closest to the pinion gear absorbs forces that attempt to press the pinion gear from the crown wheel, while the farther bearing absorbs the forces that attempt to press the pinion gear into the crown wheel. The bearings have the correct preload by means of a nut fitted on the shaft being tightened until the correct bearing preload is obtained.

The pinion gear's gear contact to the crown wheel is governed by shims. A stuffing box in the front edge of the left-hand housing seals against the pinion shaft.

The pinion is matched together with the crown wheel.

Scheme 27

The differential consists of a crown wheel and differential housing with associated gears. It is fitted in the left-hand half of the final drive gear housing. The crown wheel is laser welded to the differential housing.

The differential is made up of a forged housing, two differential gears and two drive shaft gears. The differential gears are mounted on a ground and hardened shaft journal, the ends of which are attached into the differential housing and locked by the crown wheel. The drive shaft gears are internally equipped with splines in which the drive shafts fit. Behind the gears, towards the differential housing, there is a spring-loaded thrust washer which provides the drive shaft gears with the correct gear contact to the differential gears. The drive shafts are mounted directly in the differential housing material, the lead-throughs are equipped with lubricating grooves.

Scheme 28

The differential unit is mounted in two conical roller bearings. The bearings are given the correct preload at manufacture by means of shims being fitted behind the bearing races in the respective housing.

The function of the differential is to allow the outer wheel to rotate faster than the inner wheel when cornering.

Scheme 29

Components

The all-wheel drive system consists of 6 main components

1. transfer case
2. propeller shaft
3. rear drive clutch solenoid valve
4. differential clutch pump
5. rear differential clutch solenoid valve
6. rear differential clutch control module

Transfer Case

The transfer case is mounted on the side of the transmission. Its function is to take power from the gearbox and transfer it via a hypoid gear and a propeller shaft to the differential clutch.

Differential Clutch

The function of the differential clutch is to control the torque to the rear wheels. It can be varied between 0-100% drive via a hydraulically controlled multi-disc clutch. The differential clutch is bolted to the limited slip differential with 4 bolts and has a dedicated oil supply separate from the differential.

Propeller Shaft

The function of the propeller shaft is to transfer power from the transfer case to the differential clutch.

Limited Slip Differential

The limited slip differential, also referred to as the rear drive module, is located in the subframe and the drive shafts extend from it to each rear wheel. The limited slip differential consists of a hypoid gear and a differential which has a dedicated oil supply separate from the differential clutch. The limited slip differential is fully mechanical. The limited slip differential clutch, if installed, is bolted with 6 bolts to the left-hand side of the limited slip differential. Its function is to fully or partly lock the left-hand drive shaft to the differential housing. When this takes place the drive torque can be distributed between the rear wheels. The limited slip differential clutch is a disc type, and it is electro-hydraulically controlled by the rear differential clutch control module via a pressure control valve which is fitted on the limited slip differential clutch housing. The rear differential clutch control module calculates drive torque distribution. There are two variants: with and without limited slip differential clutch for the rear wheels.

Differential Clutch Pump

The differential clutch pump consists of an electric motor and a pump. It is supplied with voltage from the rear differential clutch control module. The differential clutch pump produces an operating pressure of 2700-3200 kPa (392-464 PSI). The rear drive clutch solenoid valve is electrically controlled and regulates the hydraulic pressure between 0-3000 kPa (435 PSI). It is directly connected to the rear differential clutch control module which supplies it with a pulse width modulated voltage. The rear differential control module activates the output to the differential clutch pump as soon as the engine started. The output is active until the calculated pressure is approximately 3200 kPa (464 PSI). The pressure is calculated by the rear differential control module by measuring the differential clutch pump electric motor power consumption. The higher the pressure, the greater the resistance is for the electric motor to drive the pump therefore the current required increases. When the system pressure is approximately 3200 kPa (464 PSI), the rear drive clutch solenoid valve bleeds off the excess pressure so that the pressure does not increase any further. The current to the motor does not increase any further but remains constant. When the maximum system pressure is reached, the rear differential control module shuts down the pump. Restart takes place when the calculated pressure drops below approx. 2700 kPa (392 PSI).

Rear Differential Clutch Control Module

The rear differential clutch control module is fitted on the housing. The hydraulic pressure is built up by the differential clutch pump, and is controlled by the rear differential clutch control module via the rear drive clutch solenoid valve. Utilizing information on the serial data bus, the rear differential clutch control module calculates the drive torque distribution between front and rear axles as well as the distribution between the rear wheels for vehicles with limited slip differential clutch. The rear differential clutch control module is connected to the vehicle's high speed communication bus. The serial data messages are used to determine the operating/driving conditions for the vehicle and how much drive torque should be transferred to the rear wheels. Since the rear differential clutch control module and the rear drive clutch solenoid valve are calibrated as a matched set, they must be replaced together without exception.

The rear differential clutch control module is constantly monitoring for bus communication, inputs, outputs, certain mechanical faults and internal control module faults. If relevant control module functions are missing or other mechanical or electrical faults are recognized, diagnostic trouble codes are generated.

1. Internal signals The control module has a monitoring for internal control module faults.
2. Input signals The control module has an input for an internal temperature sensor. The temperature sensor is fitted on the rear differential control module circuit board and is monitored for electrical faults. The temperature sensor is also used by the rear differential control module to calculate the current fluid and disc pack temperature in the differential clutch.
3. Output signals The rear differential clutch control module has outputs for the rear drive clutch solenoid valve and the rear differential clutch solenoid valve for the limited slip differential clutch (if equipped) as well as for the differential clutch pump. These are all monitored for electrical faults.
4. Mechanical functions The control module can diagnose clogged pressure control valves and leaking check valves.

Special Tools

Illustration Tool Number/Description CH-49158 Press Tool Kit DT-869-4 Seal Installer DT-48077 Seal Installer DT-49065 Sealer Handle DT-49126 DT-49126-10 Press Tool DT-49065 Seal Installer DT-49231 Seal Remover DT-50022 Installer J-8092 DT-8092 Universal Driver Handle J-8614-A DT-8614-A Pinion Flange Holder J-23907 GE-239097-1 Slide Hammer J-29369-1 Slide Hammer J-44873-2 Pinion Flange holder and Remove Bolts

Scheme 30

Scheme 31

Scheme 32

Scheme 33

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• COMPONENT CONNECTOR END VIEWS - INDEX
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Control Module References
• Diagnostic Repair Verification
• Diagnostic Trouble Code (DTC) List - Vehicle
• Lifting and Jacking the Vehicle
• Fastener Caution
• Propeller Shaft Replacement
• Exhaust Muffler Replacement (Single)
• Rear Wheel Drive Shaft Replacement
• Adhesives, Fluids, Lubricants, and Sealers
• Electronic Parking Brake Control Module Replacement
• Service Programming System (SPS)
• DTC C0393
• Differential Clutch Oil Inspection
• Adhesives, Fluids, Lubricants, and Sealers
• Special Tools