Complaint Concern 1

Bulletin number

LI32.50-P-079670

Component

Suspension

Summary

Complaint Concern 1 - Noises in recovery mode with the vehicle stationary Concern 2 - Noises when driving in a straight line on rough terrain Concern 3 - Noises when cornering and performing alternate steering movements Concern 4 - Non-assignable noises Cause Concern 1 - Noises in recovery mode with the vehicle stationary Concern 2 - Noises when driving in a straight line on rough terrain. These are normal operating noises of the hydraulic high-pressure pumps. Explanation: This is the "preview noise" which is heard when recovery mode is in operation, but which can also occur when driving over very uneven ground in the Comfort and Curve drive programs. This is a normal operating noise which is caused by the hydraulic high-pressure pumps (MPE). To compensate for the unevenness of the ground, large oil flows need to be generated and to do so, the MPEs turn at very high rotational speeds. Note: In the "ECO" drive program, the "Preview" function is deactivated so these noises should not occur when driving over uneven terrain; however the vehicle body will move noticeably. Concern 3 - Noises when cornering and performing alternate steering movements - reversing noise. Repeated rapid steering out of a curve generates a "grunting" noise. Explanation: This noise is caused by the MPEs when the pump's direction of rotation is reversed. Note: The reversing noise can occur in all drive programs, but is most clearly reproducible in the Curve drive program and in Curve level 3. Carry out an evaluation firstly in Curve levels 1 to 3 (at the highest Curve level 3, the noise will also be at its loudest!), and then in the Comfort drive program. Concern 4 - Non-assignable noises. Remedy Generally check whether the same noises also occur in ECO mode - in this mode the Preview/ROAD SURFACE SCAN function is deactivated and the high-pressure pumps run at reduced speed. Consequently, it is possible to differentiate between normal operating noises and unusual noises. Regarding 1, 2: Explain the high-pressure system, replacing the suspension struts or pumps is not useful, as these noises are caused by the high-pressure pump unit and should be regarded as normal operating noises. Regarding 3: This is currently a normal operating noise and represents the series production configuration; consequently replacing the components is not useful. Regarding 4: There will certainly be other unknown noises that we are not yet familiar with; therefore please report these as well. For these, create a TIPS case and include informative video recordings of the noises. The driving situation in the drive program in which the noises occur should be shown. For comparison, also attach a recording of this same driving situation in ECO mode. Additional attachments required: - Logs for control units N51/8, M67, M67/1, M67/2, M67/3. - Actual values for the pressures of the four hydraulic high-pressure pumps at standstill.

Owners of these vehicles have filed 14 complaints in the suspension category.