TSB : Safety precautions and basic information for troubleshooting and repair

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CAUTION: ABS is basically maintenance free. Testing, assembly and repair work should be conducted only by trained personnel. Lack of consideration of the points described in the article can cause damage to the system and loss in vehicle safety. ABS and ABS/EDL are vehicle safety systems; working on these systems requires specific system knowledge. Fig 1: ABS Warning Light -K47- And The Red Symbol "Brake System Malfunction" Courtesy of VOLKSWAGEN UNITED STATES, INC. The ABS warning light -K47- (right arrow) and the red symbol "Brake system malfunction" (left arrow) light up to indicate malfunctions. Refer to System malfunctions indicated via warning lamps, ABS/EDL/ASR ITT Mark 20 IE . Certain malfunctions are only recognized after the minimum speed of 60 km/h is reached (road test vehicle. Refer to Road tests ). The red symbol for "Brake system malfunction" appears in the instrument cluster. This appears in both the low-line and high-line versions. In the low-line version, the warning light for brake system -K118- is responsible for the symbol, in the high-line version, the symbol appears in the display of the driver information system. The red symbol "Brake system malfunction" cannot be activated by the ABS, ABS/EDL until ignition is switched on and 10 km/h or 2000 engine RPM has been reached. If the ABS warning light -K47 and the red symbol for "Brake system malfunction" are not lit, but the brake system is not functioning properly, check for malfunctions in traditional brake system components. Refer to 46 BRAKES - MECHANICAL COMPONENTS Refer to 47 BRAKES - HYDRAULIC COMPONENTS The OBD sequence can only be started with the vehicle stationary and the ignition switched on (or with the engine running). It is not possible to initiate On Board Diagnostic (OBD) once wheel speed has reached 2.75 km/h. On Board Diagnostic (OBD) will be aborted if a speed of 20 km/h is exceeded. While testing the ABS/EDL or ASR system, make sure that the vehicle's electrical system is not subjected to electromagnetic interference; keep the vehicle away from equipment with a high current draw such as electric welding units. Before working on the ABS, ABS/EDL system, check DTC memory to determine existing malfunctions and to perform a guided fault finding: Refer to On Board Diagnostic (OBD) ABS and ABS/EDL ITT Mark 20 IE, initiating . Do not perform work steps at the hydraulic unit other than those contained within the maintenance procedures described here. Do not replace expensive components of the hydraulic unit until after performing extensive tests.. All vehicle safety systems must be checked following work at the hydraulic unit, the electronic control module, the wheel speed sensors, or the wiring set and when components are replaced, e.g. for collision repair of the brake lines. Switch ignition off and disconnect battery Ground (GND) strap before working on ABS, ABS/EDL. Note radio code (for vehicles equipped with coded anti-theft radio). All work on the ABS system must be carried out with the utmost cleanliness. Thoroughly clean all connections and the surrounding area before disconnecting. Do not use any aggressive cleaning agents, such as brake fluid, gasoline, thinning agents, or any fluids containing mineral oil, such as oils and greases. Do not drive with the connector disconnected from control module. Make sure that brake fluid does not enter harness connectors. Observe the appropriate notes when working with brake fluid. Refer to 47 BRAKES - HYDRAULIC COMPONENTS Place parts that have been removed on a clean surface and cover. Only use lint-free cloths. Do not work with compressed air and do not move vehicle while the system is open near the hydraulic lines. After disconnecting the control module/hydraulic unit, close hydraulic line connections using repair set 1 H0 698 311 A and use transport protection for the valve domes. Refer to Hydraulic unit, servicing . This is required for various warranty claims. Only use parts in their original packing. Only unpack replacement parts immediately prior to installation. After work that requires opening the brake system, bleed brake system using VW1238/1, VAG1238 B or VAG1869 brake filler/bleeder tool. Perform basic setting on vehicles with EDL. Refer to Basic Setting (function 04) . Refer to 47 BRAKES - HYDRAULIC COMPONENTS Welding work performed with electrical welding equipment can affect the ABS, ABS/EDL system. Refer to Special information, Body No 19 During final road test. Refer to Road tests be sure to engage at least one regulated braking procedure.