Safety Precautions and Test Procedures
Safety Precautions and Test Procedures
Improper repairs performed on the rear final drive 0BF and 0BE can cause the final drive to malfunction.
• Testing, assembly, and repair work may only be performed by qualified personnel.
Correct Fluid Level
• Make sure the rear final drive is filled with the correct quantity of oil. Refer to => [ Engine Codes, Transmission Allocations, Ratios and Capacities ] Engine Codes, Transmission Allocations, Ratios and Capacities.
• Leaks in the rear final drive, for example, at the sealing surfaces or shaft seals, must be repaired. The gear oil can also leak out of the oil overflow holes between the left - arrow 1 - or right - arrow 2 - chambers and the rear final drive.
Rear final drive malfunctions.
• The rear final drive must not be driven if leaks are found or if the gear oil level is too low.
• Repair any leaks found in the rear final drive.
• Check the ATF or gear oil level and fill if necessary.
• Only the ATF or gear oil is available as a replacement part may be used. Refer to the Parts Catalog.
• The rear final drive will have to be replaced if repairing the leaks is not possible.
Rear Final Drive Performance.
Transmission control malfunctions.
• Follow all instructions exactly when replacing any parts on the transmission. Doing so guarantees the performance and the response characteristics of the rear final drive 0BF and 0BE.
Replacing Parts on the Transmission
• The adaptation values for the transmission response (for example, clutch wear, fluid aging) vehicle diagnostic tester must be transferred when the All Wheel Drive (AWD) control module (J492) is replaced otherwise the performance of the rear final drive will be impaired.
• The clutch classification must be programmed into the AWD control module see vehicle diagnostic tester whenever one of the chambers or the complete rear final drive is replaced. The performance of the rear final drive will be impaired if the AWD control module does not get programmed with the new clutch classification. The classification designation on the rear final drive housing must be made irrecognizable when replacing a chamber. The new classification designation must be made on the housing for the new chamber.
• Do not lay the rear final drive on any hydraulic control unit components, for example, the clutch valves. This will damage the components.
Replacing the oil pressure/temperature sensor (G437) and/or oil pressure/temperature sensor 2 (G640).
• The sensor identity must be adapted in the AWD control module see vehicle diagnostic tester after replacing the oil pressure/temperature sensor or oil pressure/temperature sensor 2.
• The oil pressure/temperature sensor and oil pressure/temperature sensor 2 should not be replaced together at the same time because a valid sensor identity is needed for the allocation of the rear final drive AWD control module. The AWD control module would interpret the changing of both sensors at the same time as if the rear final drive was replaced. This will erase all adaptation values stored in the control module and will impair the performance of the rear final drive.
• If both the oil pressure/temperature sensor and oil pressure/temperature sensor must be replaced due to mechanical damage, then this must be performed in two steps. After replacing the first sensor, the AWD control module must be reprogrammed with its identity see vehicle diagnostic tester. Then the same applies to the second sensor.
• If both the oil pressure/temperature sensor and oil pressure/temperature sensor 2 have to be replaced at the same time due to an electrical malfunction, then the AWD control module must be programmed with the new clutch classification see vehicle diagnostic tester. The ATF must also be replaced. Refer to => [ ATF in Rear Final Drive 0BF and 0BE, Draining ] ATF in Rear Final Drive 0BF and 0BE, Draining.
Check the Torque Displacement.
Perform 22 - Check torque displacement:
• Working on the rear final drive wiring
• Working on the valves: all wheel drive clutch valve (N445) and all wheel drive clutch valve 2 (N446)
• Working on the hydraulic control unit
=> [ Torque Displacement, Checking ] Torque Displacement, Checking