General Notes

General notes

WARNING!
- The systems are fundamentally maintenance free.
- Checking, removing, installing and servicing may ONLY be performed by qualified personnel.
- Ignoring points listed in the repair manual can cause damage to the system and greatly reduce driving safety.

Note:
- Before carrying out repairs to the ABS, determine the cause of the malfunction using On Board Diagnostic (OBD).
- Only use parts in their original packaging.
- Only unpack replacement parts immediately prior to installation.
- Only use lint-free cloths.
- 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.
- Do not unplug the connector on the hydraulic control unit unless the ignition is switched off.
- Absolute cleanliness is required when working on the anti-lock brake system. Do not use any products which contain mineral oil, oils, grease and cleaning solvents.
- Make sure that brake fluid does not enter harness connectors.
- After finishing any work that required opening the brake hydraulic system, bleed the brake system (using brake filler and bleeder unit VAS 5234).
- When working with brake fluid, observe relevant safety precautions and notes.
- 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).
- Do not work with compressed air and do not move vehicle while the system is open.
- When painting, electronic control module can be exposed to a maximum temperature of 95 � C only briefly, and to a maximum of 85 � C for longer periods (approx. 2 hours).
- Always check control module coding when installing a new hydraulic control unit.

Road test vehicle
- Some DTCs are only recognized by On Board Diagnostic (OBD) while the vehicle is moving. You can check the system during a road test. During road test, drive at a speed of at least 60 km/h for 30 seconds. Check traffic conditions and perform an ABS regulated braking when appropriate. You will feel a pulsing in the brake pedal indicating the system is active.

WARNING!
Driving the vehicle after On Board Diagnostic (OBD) has detected a malfunction presents the risk of accident. The brake system will only be partially functional. Because brake pressure at the rear wheels is no longer regulated via Electronic Brake Distribution (EBD), the rear wheels tend to brake excessively. This causes the rear of the vehicle to break loose.

WARNING!
To reduce the risk of accident during road tests, always proceed as follows:

Audi TT Coupe:
- Use only the VAS5051 tester or the VAG1551 Scan Tool (ST) to read measuring value blocks. Always secure scan tool to the rear seat and have operated from there by a second technician.
- Due to limited space, the passenger seat must be adjusted as far forward as possible and the seat back adjusted to the forward-most engaged position using the hand wheel. Do not use the seat back release lever for this purpose.

Audi TT Roadster:
- For the Audi TT Roadster, use only the VAG1552 mobile scan tool with passenger-side airbag switched off.
- Switch off the passenger-side airbag using the key switch in the glove compartment.
- Switch on passenger-side airbag after completing work.