Brakes - Brake Pulsation Diagnostic Information
46 Brake pulsation diagnostic guidelines
46 12 23
2022584/3
June 18, 2012.
Supersedes Technical Service Bulletin Group 46 number 12 - 19 dated January 18, 2012 for reasons listed below.
Affected Vehicles
Condition
Brake pulsation.
Technical Background
Brake pulsation may be related to:
^ Rust buildup and/or brake pad marks on discs.
^ This may be due to moisture exposure or prolonged periods of the vehicle not being driven.
^ This may affect vehicles at PDI or those already delivered to customers.
^ Brake disc thickness variation.
^ Thermal distortion of brake discs.
^ Worn brake pads and discs.
^ Faulty suspension components (ball joints, tie rods, bushing, etc.).
^ Imbalance of wheels and tires.
Production Solution
Audi A4 Quattro Sedan (8K2) L4-2.0L Turbo (CAEB) Page 151
Not applicable.
Service
Diagnosis
^ Verify all complaints with a test drive.
^ Complete the Brake Pulsation Service Tree (attached). Fill it out as you work on the vehicle and attach a copy to the repair order.
^ Also check the following points:
^ At what speed does the pulsation start? At what speed does the pulsation stop?
^ With how much pedal pressure (light / medium / high) can the pulsation be created?
^ Where is the pulsation observed? (steering wheel / brake pedal / seat / front of the vehicle)
^ Roll the vehicle in the established speed range without braking and check for vibrations.
^ If necessary, clean the disc brakes of any corrosion or residues.
^ Always use the attached Brake Disc/Pad Measurement Form (announced in Warranty Circular AWA 05-06) to document brake disc and pad
thickness. Attach a completed copy to the repair order.
Rust buildup and/or brake pad marks on brake discs
Every effort must be made to avoid replacing brake discs if they can be cleaned off by performing ABS stops as described in the "Diagnose" portion
of Brake Pulsation Service Tree.
Tip: Rust buildup due to incomplete Inventory Maintenance Procedures as outlined in the Inventory Maintenance Checklist is not covered under
Warranty.
Thermal distortion of brake discs
Blue burn marks on brake discs are evidence of extremely high thermal loading of brake system. This results in permanent damage to brake discs
and pads.
If vehicle is driven aggressively, brakes must be cooled down by driving around with minimal braking before parking vehicle for extended periods of
time.
Tip: This type of damage cannot be repaired under warranty.
Worn brake pads and discs
As brake discs and pads wear, their dampening effects are reduced.
Faulty suspension components and/or imbalance of wheels and tires
Inspect condition of these components. All values must be within factory specifications.
Make sure only OEM components are on vehicle.
Warranty
This TSB is informational only and not applicable to any Audi warranty.
Additional Information
All parts and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Department and service
manuals for the latest information.
