SI B 34 08 08
Brakes October 2008
Technical Service
This Service Information bulletin supersedes SI B34 08 08 dated October 2008.
designates changes to this revision
SUBJECT
Brake Squeal from Pad Wear Sensor
MODEL
E90, E91, E92, E93 (3 Series)
SITUATION
Depending on the driving conditions, the occasional brake squeak and/or squeal is normal. The condition listed in this bulletin occurs during all light to moderate brake applications and is caused by contact between the brake pad wear sensor and the brake rotor/disc. This situation can occur on the front or rear axle brakes.
CAUSE
The geometry of the brake wear sensor, combined with individual driving habits, can result in a particular wear pattern which causes a squeaking and/or squealing noise whenever the brakes are applied with light to moderate force.
CORRECTION
In the case of a customer complaint, road test the vehicle to determine the source of the noise. If the noise is coming from the brake system, inspect the brake pad wear sensor of the affected axle. If the sensor is in contact with the rotor/disc, remove the sensor and drive the vehicle.
If the noise is not eliminated, further diagnosis is required to determine the cause of the noise.
If the noise is eliminated, replace the brake pads and wear sensor of the affected axle.
Measure and record the thickness of each of the brake pads which will be replaced. Refer to the Warranty section of this bulletin for important information regarding the correct usage of warranty defect codes based on brake pad thickness.
Refer to the appropriate Repair Instructions:
RA 34 11 000 "Removing and installing/replacing brake linings on both front disc brakes"
RA 34 21 200 "Removing and installing/replacing brake linings on both rear brake discs"
Whenever the brake pads are replaced, the CBS data must be reset accordingly.
PARTS INFORMATION
For the part numbers of brake components, please refer to EPC/ETK. Only replace parts on the affected axle as listed under CORRECTION in this bulletin.
WARRANTY INFORMATION
Covered under the terms of the BMW New Vehicle Limited Warranty or the BMW Maintenance Program.
Please refer to the following defect codes listed below, based on remaining brake pad thickness, to ensure proper coding of the claim.
Claims which are submitted using incorrect coding information will be subject to either a refusal or debit.
Brake pad thickness which measures between 7.5 mm and 3.8 mm should be claimed using the defect code below for the brake pad wear sensor noise .
Defect Code:
34 11 04 39 00
Front brake pad wear sensor unpleasant noises
Labor Operation:
Labor Allowance:
Description:
Refer to KSD
Defect Code:
34 21 19 39 00
Rear brake pad wear sensor unpleasant noises
Labor Operation:
Labor Allowance:
Description:
Refer to KSD
Brake pad thickness which measures 3.7 mm or less must be claimed using the following applicable BMW Maintenance Program defect code.
Defect Code:
34 11 00 77 MP
Replacing brake pads, front
Labor Operation:
Labor Allowance:
Description:
Refer to KSD
Defect Code:
34 21 00 77 MP
Replacing brake pads, rear
Labor Operation:
Labor Allowance:
Description:
Refer to KSD
Brake pad thickness which measures greater than 7.5 mm will not have a brake pad wear sensor that contacts the brake disc.
If these vehicles have a brake noise complaint, further diagnosis is required to determine the root cause. If diagnosis determines that all the brake components are performing adequately, but the vehicle still exhibits a brake noise which is constant (not intermittent) and reproducible, then the appropriate defect codes to use are listed below.
Defect Code:
34 00 01 39 00
Front axle brakes squeaking
Labor Operation:
Labor Allowance:
Description:
Refer to KSD
Defect Code:
34 00 11 39 00
Rear axle brakes squeaking
Labor Operation:
Labor Allowance:
Description:
Refer to KSD
If the brake discs require replacement (as outlined to the Repair Manual Instructions), claim with the repair defect codes listed here for applicable warranty repairs or the appropriate BMW Maintenance Program defect code.
http://www.bmwtis.com/tsb/bulletins/...p/B340808g.htm