Suspension - Vehicle Lowers After Sitting
VEHICLE LEVEL LOWERS AFTER BEING PARKED(P-B-32.50/34E, NOVEMBER 24, 2008)
Topic Number LI32.50-P-046012
Version 2
Design Group 32.50 Active body control (ABC)
Date 09-17-2009
Validity Model 215.373/374/375/376/378/379
Model 220.170/173/174/175/176/178/179, Equipped with Code 487 (Active body Control)
Model 230.474/475/476/479
Reason for change Parts information updated/Supercedes DTB P-B-32.50/34e
Reason for block
Complaint:
Vehicle Level Lowers After Being Parked
Cause:
Fault codes stored
Remedy:
NOTE:
The vehicle's level may lower at any of the following: an individual strut, front or rear axle, right or left vehicle side and/or complete vehicle.
NOTE:
For both conditions listed below, large temperature differences in the ABC suspension system between operating and when stationary for an extended period can also cause the vehicle to lower slightly. The lowering is caused by temperature dependent volume changes in the ABC oil within the suspension struts. The vehicle can lower up to 10mm when the temperature difference is 30°C (ABC operating temperature 20°C/outside ambient temperature -10°C).
Condition 1
If a vehicle lowers after being stationary (engine off) within approximately one week, this is likely due to internal leakage in the check valve of the front (Y36/1) or rear (Y36/2) axle valve blocks. The internal leakage is the result of deposits or contamination on the valve seat of the check valve. In order to remove the deposits, filter the ABC system (reference WIS document AR32.50-P-0025A).
If the complaint still continues to occur after the above procedure, the respective valve block must be replaced with revised parts, follow the procedure listed below.
NOTE
For Model 230, corresponding hydraulic lines and a guard plate are also required; refer to the parts information table.
1. Clean the oil reservoir, especially the lower portion of the tank which has a small hollow formation (Figure 1, circle) that can get a build-up of debris. you may need to pick the debris out of this area. refer to document GF32.50-P-4900A.
2. Filter ABC system (refer to WIS document AR32.50-P-0025A. Rodeo procedure should be performed for 0.5 hours in order to ensure fluid is at full operating temperature.
3. Raise the vehicle level with STAR Diagnosis to the maximum level via the following menu path: Control Units --> Chassis --> Suspension --> ABC Active Body Control --> Control and Locking valve (for each suspension strut) -> F3 (Switch on) -> F5 (+) -> F4 (Switch off).
4. Bleed oil from struts via bleed screws. refer to WIS document AR32.50-P-00010-01N.
5. Repeat steps 3 and 4 three times. This removes any debris contained within the struts. Ensure that there is sufficient oil within the resolver between each bleed routine.
6. Remove valve block. Refer to the following WIS documents: Model 215/220 - AR32.50-P-0001N and AR32.50-P-0002N and Model 230 - AR32.50-P-0001R and AR32.50-P-0002R.
7. Throughly clean threaded connections/hydraulic lines.
8. Replace valve block. Refer to the following WIS documents: Model 215/220 - AR32.50-P-0001N and Model AR32.50-P-0002N and Model 230 - AR32.50-P-0001R and AR32.50-P-0002R.
9. Filter ABC system. Refer to WIS document AR32.50-P-0025A. Rodeo procedure should be performed for 0.5 hours in order to ensure fluid is at full operating temperature.
10. Ensure correct ABC fluid level.
CAUTION
It is imperative that the utmost attention for cleanliness be observed when working on the ABC suspension system in order to ensure that no contamination enters the system. Small particles of debris can contaminate the hydraulic fluid, thus causing internal leakage.
Condition 2
If a vehicle lowers only after being stationary (engine off) for more then approximately a week, this is a characteristic of the hydraulic design and is not a complaint that requires a repair. The check valves in the front and rear axle valve blocks have a metal valve seat. The inherent design of this sealing method, required for system durability, permits a limited level of leakage which can result in the vehicle slowly lowering. If the vehicle does not lower significantly until after approximately one week has passed, do not perform any repair attempts.
NOTE:
The dropping vehicle level is not caused by a suspension strut. The suspension strut can only be responsible for a dropped vehicle level if it exhibits a external leak. This leak can be recognized by oil fouling on the boot.
NOTE:
The following allowable labor operations should be used when submitting a warranty claim for this repair. This information has been generated on November 11, 2008. Please refer to Netstar -> Star TekInfo -> Star Time for the most current labor time allowance.
Attachments
Symptoms
Control unit/Fault code
Parts
Work units
WIS - References
Validity
Attachment - Figure 1