ABS System - Buzzing/Droning Noises
Date: April 24, 2003Order No.: P-B-42.46/28
Supersedes:
Group: 42
SUBJECT:
Model 230.474/475, Model Year 2003
Buzzing/Droning Noises During Pressure Buildup of SBC System
If you receive customer reports in the above models of buzzing / droning noises from the SBC system, please perform the following procedure.
Caution:
Only trained workshop personnel should perform service on the SBC system. Reference WIS document SI42.46-P-0001D.
1) Using STAR Diagnosis deactivate the SBC system. Reference WIS document AS42.46-Z-0001-01A.
2) Install and tighten service tool clamp (part number 000 589 40 37 00) on the suction line approximately 15 cm (6 inches) from the SBC hydraulic unit in order to minimize brake fluid loss (Figure 1).
3) Loosen hose clamp for the suction line at the SBC hydraulic unit fitting and remove hose.
4) Cut off approximately 6.5 cm (2.5 inches) from the end of the suction line.
Note:
Ensure that the cut hose surface is clean and straight with no textile cords protruding. Additionally ensure that no debris gets into the suction line.
Note:
Do not discard the 6.5 cm length of hose previously cut-off the suction line, it will be reused in a later step.
5) Cut off approximately 3 cm (1-3/16 inches) from the end of the clamped suction line (vehicle side). This section of hose will not be reused and can be discarded.
Note:
Ensure that the cut hose surface is clean and straight with no textile cords protruding. Additionally ensure that no debris gets into the suction line.
6) Install the pulsation damper between the two hose ends and install the hose clamps (Figure 2).
Note:
The pulsation damper can be installed in either direction. The direction of flow through the pulsation damper is not relevant.
7) Wrap the pulsation damper and the hose clamps with approximately 40 cm (15 inches) of adhesive backed felt (Figure 3).
Note:
The felt wrap is necessary to eliminate chafing points and noise transmission resulting from vibration.
8) Install suction line with pulsation damper on the SBC hydraulic unit fitting and secure with clamp.
Note:
The suction line must be installed tension free and must not contact the brake lines or the return line.
9) Remove the service tool clamp installed in step 2.
10) Bleed the SBC system using STAR Diagnosis.
Note:
STAR Diagnostics with software version 10/2002 or newer must be used.
Parts Information
In Case of Warranty