Function 08-Read Measuring Value Block

Read Measuring Valvue Block (VAG 1551 Scan Tool Function 08)

The ABS control module can transfer a considerable amount of test data. This data delivers information about the operational condition of the system and/or sensors. In many cases the transferred test data provides support for troubleshooting and repair. The test data has been summarized into single display groups because all the information cannot be evaluated at the same time. The information can be selected via display group numbers.

NOTE: For scan tool connection instructions refer to Connecting and Selecting Function under Scan Tool Operation.

- Indicated on display:

Rapid data transfer HELP
Select function XX

1. Press buttons -0- and -8- to select "Read Measuring Value Block" function 08, and press -Q- button to confirm input.

- Indicated on display:

Rapid data transfer Q
08-Read Measuring Value Block

2. Press -Q- button to confirm input.

- Select display group below for required measuring value block.

DISPLAY GROUP 001 - ABS Wheel speed sensor assignment

- Indicated on display:

Read measuring value block
Input display group number XXX

3. Press buttons -0-, -0- and -1- (display group 001).
4. Press -Q- button to confirm input.

- Indicated on display:

Read measuring value block 1
Km/h 0 Km/h 0 Km/h 0 Km/h

^ Momentary actual wheel speed is displayed. These are used to check the ABS wheel speed sensor assignments to the wheels. (Vehicle must be raised and wheel turned by hand). Refer to table below.

- Indicated on display:

Read measuring value block 1
1 2 3 4

^ In "Read Measuring Value Block" function 08 there are always 4 display fields (arrows -1- through -4-).

Display Description Displayed on
field VAG 1551
scan tool
1 Wheel speed, LF - km/h 2 - 255
2 Wheel speed, RF - km/h 2 - 255
3 Wheel speed, LR - km/h 0 - 255
4 Wheel speed, RR - km/h 0 - 255

5. Press -C- button to end readout of display group 001.

DISPLAY GROUP 002 - ABS Wheel speed sensor signals
The ABS control module stores the first useable voltage signal from the ABS wheel speed sensors when driving away, and displays these as set values in the measured value block.

- Indicated on display:

Read measuring value block
Input display group number XXX

6. Press buttons -0-, -0- and -2- (display group 002).
7. Press -Q- button to confirm input.

EXAMPLE

- Indicated on display:

Read measuring value block 2
1 2 3 4

- In "Read Measuring Value Block" function 08 there are always 4 display fields (arrows -1- through -4-).

^ Values in display fields 1 and 2 must not be greater than 6 km/in (approx. 3-1/2 mph).
^ Values in display fields 3 and 4 must not be greater than 2 km/in (approx. 1-1/4 mph).
- Displayed values greater than these may be caused by faulty ABS wheel speed sensor installation:
^ Air gap too large between ABS wheel speed sensor and impulse rotor (check for correct installation in wheel bearing housing).
^ External damage to ABS wheel speed sensor or impulse rotor (replace damaged part).

END EXAMPLE

- Indicated on display:

Read measuring value block 2
O Km/h O Km/h O Km/h O Km/h

8. Drive away slowly until values are displayed on VAG 1551 scan tool, then refer to table.

Display Description Displayed on
field VAG 1551
scan tool
1 Wheel speed, LF - km/h 0 - 255
2 Wheel speed, RF - km/h 0 - 255
3 Wheel speed, LR - km/h 0 - 255
4 Wheel speed, RR - km/h 0 - 255

^ Deviations in values in display fields 1 and 2 below 6 km/in (approx. 3-1/2 mph) are OK (see example below).
^ Deviations in values in display fields 3 and 4 below 2 km/in (approx. 1-1/4 mph) are OK (see example below).

Example:
Read measuring value block 2
3 Km/h 6 Km/h 2 Km/h 1 Km/h

9. Press -C- button to end readout of display group 002.

DISPLAY GROUP 003-Brake light switch ABS and ABS/EDL

- Indicated on display:

Read measuring value block
Input display group number XXX

10. Press buttons -0-, -0- and -3- (display group 003).
11. Press -Q- button to confirm input.

Indicated on display:

Read measuring value block 3
0

Display Test requirements Displayed on
field VAG 1551
scan tool
1 Foot brake not operated 0
Foot brake operated 1

12. Press -C- button to end readout of display group 003.