Notes for repair work on anti-lock brake system

• Before carrying out repair work on the anti-lock brake system, determine the cause of the fault using “Guided Fault Finding”.

“Guided fault finding” is carried out on the vehicle diagnosis, testing and information system - VAS 5051-.

• Disconnect battery earth strap with ignition switched off.
• Before carrying out welding work with an electric welding unit, note ⇒ General Information; Body Repairs, General Body Repairs.
• When working with brake fluid, observe the relevant safety precautions and notes ⇒ 4 Bleeding brake system.
• After work for which the brake system had to be opened, bleed the brake system with brake filling and bleeding equipment - VAS 5234- or -V.A.G 1869- ⇒ 4 Bleeding brake system.
• During the final road test, ensure that a controlled brake test is performed at least once (pulsations must be felt at the brake pedal).
• Absolute cleanliness is required when working on the anti-lock brake system. It is not permitted to 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 cleanser, petrol, thinners or similar.
• Place removed parts on a clean surface and cover.
• After separating control unit from hydraulic unit, use transport protection for contact pins.
• If repairs cannot be carried out immediately, carefully cover or seal open components. (Use sealing plugs from repair kit 1 H0 698 311 A).
• Only use lint-free cloths.
• Only unpack replacement parts immediately prior to fitting.
• Only use genuine packed parts.
• When the system is open, do not work with compressed air and do not move the vehicle.
• During painting operations, the electronic control unit can be exposed to a maximum temperature of 95°C for only a short period, and to a maximum of 85°C for longer periods (approx. 2 hours). Ensure that no brake fluid enters connectors.