Anti-Lock Brake System (ABS) Bosch 5.3

Anti-lock Brake System (ABS) Bosch 5.3
ABS system, general information
The new Audi A6 is equipped with the Bosch 5.3 ABS/EDL system as standard equipment.
A traction control system (ASR) may also be installed as optional equipment on vehicles with front wheel drive.
The ABS hydraulic system is divided diagonally (two circuits). The vacuum brake servo unit boosts the brakes pneumatically.





Hydraulic unit -a- and control module -b- are combined as a single unit. This is therefore referred to as the hydraulic control unit.
The direct connection between these components reduces possible sources of malfunctions. The hydraulic control unit is not serviceable and must be replaced if malfunctioning.
Do not remove bolts connecting individual components of the hydraulic control unit.

ABS system, repair information

CAUTION!
^ The anti-lock brake system is basically maintenance free.
^ Testing, installation and repair work must always be carried out by properly trained technicians.
^ Non-compliance with the information may result in damage to the system and could make the vehicle unsafe to drive.

Notes:
^ Before carrying out repairs to the ABS, determine the cause of the malfunction using On Board Diagnostic (OBD).
^ Always check control module coding when installing a new hydraulic control unit.

Refer to Testing and Inspection.
- Always switch ignition off before carrying out installation or repair work. For vehicles with coded radio, obtain coding and disconnect battery Ground (GND) strap.
- When working with brake fluid, observe relevant safety precautions and notes.
- After any work that required opening the brake hydraulic system, bleed the brake system (e.g. using VAG1869), Refer to Brake Bleeding.
- During final road test, at least one ABS- controlled braking operation must be performed (appropriate pulsations must be felt at brake pedal).
Refer to Testing and Inspection.
- Absolute cleanliness is required when working on the anti-lock brake system. Do not use any products which contain mineral oil, such as oils, greases etc.
- Thoroughly clean all unions and the adjacent areas before loosening. Do not use aggressive cleaning agents such as brake cleaner, fuel, thinners or similar chemicals.
- Place parts that have been removed on a clean surface and cover.
- Carefully cover over opened components or seal, if repairs are not carried out immediately (use sealing plugs from repair kit 1 H0 698 311 A).
- Use lint-free cloths only!
- Only unpack replacement parts immediately prior to installation.
- Only use parts in their original packaging.
- Do not work with compressed air and do not move vehicle while the system is open.
- Make sure that brake fluid does not enter harness connectors.
- When painting vehicle, electronic control unit can be exposed to a maximum temperature of 95° C (203° F) only briefly, and to a maximum of 85° C (185° F) for longer periods (approximately 2 hours).
- Before carrying out welding work with an electric welder observe all relevant notes and safety precautions:
Refer to Body and Frame.