S 600 (220.176) V12-5.5L Turbo (275.960) (2005)
Acceleration Sensor: Customer Interest
Suspension - Height Randomly Changes
Date: October 29, 2008
Order No.: P-B-32.50/35c
Supersedes: P-B-32.50/35b dated Feb. 22, 2008
Group:32
Revision History
SUBJECT: Model 215.373/374/375/376/378/379
Model 220.067/083/170/173/174/175/176/178/179/183/184, Equipped with Code 487 (Active Body Control)
Model 230.471/472/474/475/476/477/479, Up to VIN F118817
Random Vehicle Level
If you receive customer reports in the above model vehicles of the vehicle's suspension level randomly lowering while driving and/or rapid sporadic level
changes shortly after stopping the vehicle, replace the body acceleration sensors (reference WIS document GF32.31-P-4100A), with a manufacturing
date greater than 02 W 01 (Year 2002, week 01) (Figure 1).
NOTE:
Do not replace any other ABC suspension components.
In both of the above scenarios, vehicle level changes typically occur intermittently and predominately after driving for extended periods. The vehicle's
level adjusts without obvious cause, and usually quickly moves upwards or downwards, and then rapidly corrects back to the specified level.
Random level movements (while driving) only occur when the ABC suspension system is in Active mode (i.e. when the vehicle is in motion). Thus, the
above mentioned level movements cannot occur when the ABC system is in Passive mode (i.e. vehicle stopped). Since the ABC system does not switch
to Passive mode until a few seconds after the transmission gear selector is positioned into Park or a significant braking torque is applied for several
seconds, sporadic level conditions may exist shortly after stopping the vehicle. Random level conditions may also exist shortly after stopping the vehicle
if the vehicle is stationary but an insufficient amount of braking torque is applied, thus causing the system not to switch to Passive mode.
NOTE:
The random level control is the result of tolerance contact issues on the printed circuit board of the body acceleration sensors [B24/3-front left,
B24/4-front right, B24/5-rear left (Model 230), B24/6-rear right (Model 220/215)], in combination with the sensors heating up after an extended
period of driving. The contact issue can result in a higher internal resistance on the printed circuit board causing the sensor to output an incorrect
signal, thus initiating an ABC adjustment.