| If a problem exists on the vehicle, perform the fault-finding procedure in the following sequence: |
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| First switch on the ignition and observe the warning lamps. This will give an initial indication of what to look for (vehicles without ESP → Chapter, vehicles with ESP → Chapter). |
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| Observe the test requirements detailed on → Chapter. |
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| Connect vehicle diagnostic, testing and information system -VAS 5051 A- and select vehicle system “03 - Brake electronics” → Chapter. |
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| Check the control unit version → . |
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| Interrogate the fault memory (vehicles without ESP → Chapter, vehicles with ESP → Chapter). If a fault is present in the memory: print out the content of the fault memory and then erase the fault memory. |
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| Conclude the transfer of data with the function “06 - End output”. |
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| Eliminate the fault using the fault tables. |
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| If a component is indicated as being defective, only renew it if you are sure that the electrical wiring for that component is in proper condition. The wiring must be able to transmit the necessary signals without interference or resistance. Check the wiring for: |
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| Corrosion and loose contacts in the connectors and earth connections. If any of the plug contacts are bent, broken or corroded, use the wiring repair kit -VAS 1978- to fit new contacts. |
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| Check that the connectors are plugged in correctly (with retainers engaged). |
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| After completing the repair, select vehicle system “03 - Brake system” for a second time. Interrogate and erase fault memory. |
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| Conclude the transfer of data with the function “06 - End output”. |
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| Switch off ignition and detach diagnostic connector. |
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| Perform a road test → Chapter to check the function of the system. If any of the warning lamps light up during the road test, repeat the fault finding procedure. |
WARNING | If the connector is not plugged into the ABS with EDL control unit -J104- when the vehicle is moving, this may result in a spurious (non-existent) fault being registered in the fault memory of another control unit. The function of the brake system will be impaired. The brake pressure at the rear wheels is no longer controlled by the electronic brake pressure distribution function. This can result in excessive braking at the rear, and the tail of the vehicle may break out unexpectedly. |
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Note |
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