| General information on the anti-lock brake system |
WARNING | The anti-lock brake system is basically maintenance-free. |
| Testing, removing, installing and repair work may only be performed by qualified personnel. |
| Failure to observe the information described in this Workshop Manual may result in damage to the system and could make the vehicle unsafe. |
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| Before carrying out repair work on the anti-lock brake system, determine the cause of the problem using self-diagnosis. |
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| If a new hydraulic control unit has been fitted, you must check that it has the correct coding; use vehicle diagnosis, testing and information system -VAS 5051B- or -VAS 5052-. |
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| Always switch off the ignition before carrying out installation or repair work. On vehicles with a coded radio, find out the anti-theft code and disconnect the battery earth strap. |
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| When working with brake fluid, observe the relevant safety precautions and notes → Chapter. |
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| Always bleed the brake system (using brake filling and bleeding equipment -VAS 5234-) after all work which involves opening the hydraulic system. In addition, a high- and low-pressure test should be carried out on the brake system → Chapter. |
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| During the final road test, ensure that at least one ABS-controlled braking operation is performed (pulsations must be felt at the brake pedal). Refer to vehicle diagnosis, testing and information system -VAS 5051B- or -VAS 5052-. |
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| Absolute cleanliness is required when working on the anti-lock brake system; avoid any products that contain mineral oil, such as oil, grease, etc. |
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| Thoroughly clean all connections and the adjacent areas before loosening; do not use aggressive cleaning agents such as brake cleaner, petrol, thinners or similar. |
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| Place removed parts on a clean surface and cover them up. |
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| Carefully cover or seal open components if repairs are not to be carried out immediately. (Use sealing plugs from repair kit 1H0 698 311 A) |
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| Do not use fluffy cloths. |
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| Only remove replacement parts from packaging immediately prior to installation. |
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| Only use genuine parts from original packaging. |
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| When the system is open do not work with compressed air and do not move the vehicle. |
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| Ensure that no brake fluid enters electrical connector. |
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