Antilock Brakes / Traction Control Systems: Service Precautions

Safety precautions and general troubleshooting information

CAUTION!
^ ABS is a vehicle safety system, the appropriate knowledge is necessary to work on the system.
^ In order to check complaints and to be able to carry out specific troubleshooting, DTC memory must be checked before beginning work on the ABS system.
^ Only disconnect harness connectors when the ignition is switched off.
^ Observe the appropriate instructions regarding the handling of brake fluid.
^ ABS malfunctions are indicated by the ABS warning lamp lighting up; certain malfunctions will only be recognized at speeds above 20 km/h (approx. 13 mph) (road test).
^ If the ABS Warning Light -K47- and the warning light for brake system -K118- warning lamps do not light up, but the brake system is not functioning correctly, check the conventional braking system.

Road test

WARNING!
^ If you drive the vehicle after a malfunction has been detected by OBD, bear in mind that the function of the brake system is limited, and there is a risk of accident. The brake pressure at the rear wheels is no longer controlled by the Electronic Brake Distribution (EBD) function. This can result in excessive braking at the rear, and the vehicle may skid unexpectedly under braking.
^ When driving or riding in an airbag-equipped vehicle, NEVER hold the scan tool or other test equipment in your hands or lap while in motion. Objects between you and the airbag increase the risk of injury in an accident.
^ During a test drive in an airbag-equipped vehicle, test equipment must always be fastened to and operated from the rear seat by a second technician.

Safety precautions

WARNING! Brake fluid is poisonous.

CAUTION!
^ Brake fluid must not contact painted parts.
^ Brake fluid absorbs moisture from the air and must therefore be replaced every two years. Use only new, unused and approved brake fluid that complies with MVSS 116 DOT 4.
^ Do not use silicone-based brake fluid (DOT 5). Even the smallest traces can cause severe corrosion in the brake system.

If one or two chambers in the brake fluid reservoir are completely empty (e.g. leaks in braking system) bleed the hydraulic unit with the V.A.G 1551 or VAS 5051 Scan Tool in "basic setting" function.

CAUTION! Do not exceed filling pressure of 1 bar (14.5 psi) when filling brake fluid using VAS 5234. The brake system will not be completely bled if excessive pressure is used.