Volkswagen Workshop Service and Repair Manuals

The ABS designation has been changed:

Previously: Teves 20 GI

New: ITT Mark 20 GI up to 06/97

The work sequence and function has not changed because of the new designation. Both ABS systems are identical.

From 07.97 (model year 98) the following ABS system was introduced.

ITT MARK 20 IE

This ABS system is nearly identical with the ITT Mark 20 GI. The difference is the control unit software.

The self-diagnosis relates to the electrical/electronic part of the ABS, in other words only faults via the electrical connection to the control unit are recognised (e.g. speed sensor open circuit).

The 25 pin ABS control unit -J104- forms with the hydraulic unit a compact unit. The unit is located on the left of the engine compartment. The control unit is equipped with a fault memory. The diagnostic connections are located behind driver's stowage box.

The control unit recognises faults and malfunctions during vehicle operation and stores them in a permanent memory, the contents of which remain despite the lack of battery voltage.

Sporadic (isolated) faults will also be recognised and stored. But if these faults do not occur again within the next 50 vehicle starts and driving off sequences then with the exception of "control unit defective", the fault memory will be erased (forget fault counter).

After switching on the ignition and/or starting the engine the ABS warning lamp -K47- lights up for approx. 2 seconds.

During this period a test sequence (self-check) is run in the control unit for the following functions:

• ◆ The voltage supply is checked, at least 10.0 Volt
• ◆ The control unit including the valve windings are checked
• ◆ Control unit coding checked
• ◆ A static check of the speed sensor (no speed signal),
• ◆ If after driving off and exceeding a speed of approx. 20 km/h (approx. 13 mph) the speed signal is not OK. the ABS warning lamp -K47- will light up again.

Fault reader V.A.G 1551 or tester VAS 5051

The self-diagnosis must be initiated at the commencement of fault finding. Electrical faults which influence the braking characteristics will be stored. They can be interrogated either with the fault reader V.A.G 1551 or with the tester VAS 5051.

The fault information displayed is used in conjunction with a fault table which has information on the possible fault causes for pin-pointed repair measures.