LI32.50-P-072071

Noise Complaints Relating To The eSuspension
Topic number
LI32.50-P-072071
Version
1
Function group
32.50 Active Body Control (ABC)
Date
12-18-2020
Validity
Model series 167 with SA code 489/Airmatic and with SA
code 490/eSuspension. Except AMG model designations.
Reason for change
Reason for block
Complaint:
1. Noises in recovery mode with the vehicle stationary
2. Noises when driving in a straight line on rough terrain
3. Noises when cornering and performing alternate steering movements
4. Non-assignable noises
Attachments
File
Description
BouncingNoise.MOV
1. and 2. Normal operating noises of the high-pressure
pump in recovery mode and when driving in a straight line
on rough terrain.
VID_20200907_165939_cut.mp4
3.Reversing noise of the high-pressure pump when steering quickly in the opposite direction
Cause:
Complaint 1. Noises in recovery mode with the vehicle stationary
Complaint 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 an expected 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.
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Note:
In the "ECO" drive program, the function is deactivated so these noises should not occur when driving over uneven
terrain; however the vehicle body will move noticeably.
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.
4. Non-assignable noises
For procedure, see Remedy.
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 complaints, create a PTSS 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
Symptoms
Chassis/suspension / Suspension/Dampening / Suspension system noises / whistles/hisses
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Control unit/fault code
Control unit
Fault code
Fault text
N51/8 - Active suspension and damping system (Active suspension) (ESPC167)
-
M67 - Electrohydraulic control- ler unit LEFT FRONT (EHSE)
(MPU167FL)
-
M67/1 - Electrohydraulic controller unit RIGHT FRONT
(EHSE) (MPU167FR)
-
-
M67/2 - Electrohydraulic controller unit LEFT REAR (EHSE) (MPU167RL)
-
-
M67/3 - Electrohydraulic controller unit RIGHT REAR (EHSE) (MPU167RR)
-
-
Parts
Part number
ES1 ES2 Designation
Quantity Note
EPC
A 167 320 96 01
Hydraulic pump, right front
1
Replacement of part is not useful,
create a TIPS case
X
A 167 320 95 01
Hydraulic pump, left front
1
Replacement of part is not useful,
create a TIPS case
X
A 167 320 97 01
Hydraulic pump, left rear
1
Replacement of part is not useful,
create a TIPS case
X
A 167 320 98 01
Hydraulic pump, right rear
1
Replacement of part is not useful,
create a TIPS case
X
A 167 320 29 04
Suspension strut, front left and 2
right
Replacement of part is not useful,
create a TIPS case
X
A 167 320 62 04
Right rear shock absorber
1
Replacement of part is not useful,
create a TIPS case
X
A 167 320 74 03
Right rear shock absorber
1
Replacement of part is not useful,
create a TIPS case
X
A 167 320 61 04
Left rear shock absorber
1
Replacement of part is not useful,
create a TIPS case
X
A 167 320 73 03
Left rear shock absorber
1
Replacement of part is not useful,
create a TIPS case
X
Validity
Vehicle
Engine
Transmission
GLS (167)
*
*
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