Safety Precautions

Safety precautions
Observe if test and measuring instruments are required during a test drive:
^ Test and measuring instruments must be secured to rear seat and operated by a 2nd person from this location.
^ When test and measuring instruments are operated from the front passenger seat there is a danger that the person sitting there could be injured in an accident when the airbag is triggered.

- Connect V.A.G 1551 Scan Tool and select address word 03 for"Brake electronics" with ignition switched on.

Indicated on display
- Press keys 0 and 8 to select function "Read measured value block".

Indicated on display
- Confirm entry with key Q.

Indicated on display
- Enter display group number.

List of selectable display group numbers

List of selectable display group numbers:

1) Four-wheel drive vehicles with Haldex coupling only.

2) Vehicles with automatic transmission only.

Test sequence and test tables with measured values

Checking speed sensor allocation

Display group number 001
- Press keys 0, 0 and 1.
- Confirm entry with key Q.

There are always 4 display zones -arrows- in the measured value block. Decoding the individual values in display zones 1 to 4 can be read from the tables.

Indicated on display: (vehicle stationary)

Press C key for the next display group number entry.
If the -> key is pressed, keys 0 and 8 for work sequence "Read measured value block" must be pressed again afterwards to regain entry.

Note: For display group number 001 remember:

The actual wheel speeds are displayed. They serve to check the speed sensor allocation to the wheel. (The vehicle must be raised and the wheel must be rotated by hand by a 2nd mechanic).

Checking speed sensor

Display group number 002
- Press keys 0, 0 and 2.
- Confirm entry with key Q.

There are always 4 display zones -arrows- in the measured value block. Decoding the individual values in display zones 1 to 4 can be read from the tables.

Indicated on display: (Vehicle stationary)

Press C key for the next display group number entry.

If the -> key is pressed, keys 0 and 8 for work sequence "Read measured value block" must be pressed again afterwards to regain entry.

Note: For display group number 002 remember:

^ The reading of measured value blocks in display group number 002 must be undertaken when driving off slowly. Then the ABS Control Module (w/EDL) -J104- will store the first usable voltage signals provided by the speed sensors and display these as a fixed value in the measured value block.

1) If the deviations in display zones 1 and 2 are greater than 6 km/h (approx. 3.75 mph), these malfunctions may be present:
2) If the deviations in display zones 3 and 4 are greater than 2 km/h (approx. 1.25 mph), these malfunctions may be present:

Note: Air gap between speed sensor and rotor may be too wide.

- Check that speed sensor is attached correctly to wheel bearing housing.
^ Speed sensor or rotor exterior damaged.
- Change damaged component.

Checking brake light switch for ABS and ABS/EDL function

Display group number 003
- Press keys 0, 0 and 3
- Confirm entry with key Q.

There are always 4 display zones -arrows- in the measured value block. Decoding the individual values in display zones 1 to 4 can be read from the tables.

Indicated on display

Press C key for the next display group number entry.

If the -> key is pressed, keys 0 and 8 for work sequence "Read measured value block" must be pressed again afterwards to regain entry.

Checking data bus wiring

Display group number 125
- Press keys 1, 2 and 5
- Confirm entry with key Q.

There are always 4 display zones -arrows- in the measured value block. Decoding the individual values in display zones 1 to 4 can be read from the tables.

1) Vehicles with automatic transmission only.
^ Incorrect transmission control module or incorrect transmission control module coding.
^ Transmission control module faulty.

2) All-wheel drive vehicles with Haldex coupling only.

3) Data bus connection is interrupted or data bus wires are interchanged.