SLK 280 (171.454) V6-3.0L (272.942) (2007)
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Vacuum Brake Booster: All Technical Service Bulletins
Brakes - Whistle/Click/Thud Noise From Footwell Area
Date: October 26, 2007
Order No.: P-B-43.10/04
Supersedes:
Group: 43
SUBJECT:
Model 171.454/456/473
Model 221.171/176/177/179/186
Noises from Driver Footwell When Driving in "DISTRONIC" or "SPEEDTRONIC" Mode
If you receive customer reports in the above model vehicles of a whistling/clicking/thudding noise from the driver footwell area when driving in
Distronic or Speedtronic (cruise control) mode, the cause may be due to noises coming from the Brake Assist System (BAS) activation of the solenoid
valve in the brake booster. Since the Distronic and Speedtronic cruise control systems need to regulate speed, it may be necessary to actively increase
brake pressure. Activating the solenoid valve will apply brake pressure but it will also vibrate at a high frequency when actuated. Upon releasing brake
pressure, the solenoid is de-energized and may cause a thudding/clicking/striking noise. Please perform the following to reduce the noise.
1.
Ensure that the brake booster is not under stress.
2.
Loosen the threaded connection of the brake booster so that the housing of the brake booster is relieved of tension. Refer to WIS document
AR43.10-P-0350V (171) or AR43.10-P-0350SX (221).
3.
Retighten threaded connection.
4.
Fill the gap (approx. 1 cm) in the opening in the firewall with felt to soundproof the area.
Note:
This will not fully eliminate the problem but the sound will be reduced and masked.
On model 221 vehicles, the software for the ABR control unit can be updated to prevent the solenoid from vibrating. Using Star Diagnosis
navigate to menu item "Control Unit Adaptations" in the ABR control unit and follow the instructions within DAS.
Parts Information
Note:
The following allowable labor operations should be used when submitting a warranty claim for this repair. This information has been generated on
October 26, 2007. Please refer to Netstar --> Star TekInfo --> Star Time for the most current labor time allowance.
In Case of Warranty, use the table.
