1998 VOLKSWAGEN JETTA check engine

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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).
Read measured value block
1 Display group number: 001
0 km/h 4 km/h 0 km/h 0 km/h
Indicated on display: (Example)

Wheel speed at right rear speed sensor
(0 to 255 km/h)

Wheel speed at left rear speed sensor

(0 to 255 km/h)

Wheel speed at right front speed sensor
(0 to 255 km/h)

Wheel speed at left front speed sensor

(0 to 255 km/h)
Стр. 47из 81 ABS ITT Mk 20 IE On Board Diagnostic (OBD) program

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Checking speed sensor

Display group number 002

- Press keys 0, 0 and 2.

- Confirm entry with key Q.
Read measured value block
2
1 2 3 4
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 following tables.
Read measured value block 2
255 km/h 255 km/h 255 km/h 255 km/h
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.
Стр. 48из 81 ABS ITT Mk 20 IE On Board Diagnostic (OBD) program

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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.
Read measured value block
2 Display group number: 002
3 km/h
1)
6 km/h1)
2 km/h2)
1 km/h2)
Indicated on display: (when driving off slowly)

Wheel speed at right rear speed sensor
(0 to 255 km/h)

Wheel speed at left rear speed sensor

(0 to 255 km/h)

Wheel speed at right front speed sensor
(0 to 255 km/h)

Wheel speed at left front speed sensor

(0 to 255 km/h)
1) If the deviations in display zones 1 and 2 are greater than 6 km/h (approx. 3.75 mph), the
following malfunctions may be present:
2) If the deviations in display zones 3 and 4 are greater than 2 km/h (approx. 1.25 mph), the
following 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.
Стр. 49из 81 ABS ITT Mk 20 IE On Board Diagnostic (OBD) program

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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.
Read measured value block
3
1 2 3 4
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 following tables.
Read measured value block 3
0
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.
Стр. 50из 81 ABS ITT Mk 20 IE On Board Diagnostic (OBD) program

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Read measured value block
3 Display group number: 003
0
Indicated on display

Vacant

Vacant

Vacant

Brake light switch:
If despite pressed foot brake a -0-, or not pressed foot brake a -1- is displayed on the
V.A.G 1551 display; perform test step No. 4 of Electrical check, Page 01
-102 .
There is also a possibility that the brake light switch has not been correctly adjusted.
Adjusting brake light switch, Page 01
-131 .
0 Brake pedal not depressed
1 Brake pedal depressed
Стр. 51из 81 ABS ITT Mk 20 IE On Board Diagnostic (OBD) program

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Checking data bus wiring

Display group number 125

- Press keys 1, 2 and 5

- Confirm entry with key Q.
Read measured value block
125
1 2 3 4
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 following tables.
Read measured value block
125
Engine 1 4WD 1 Gear. 1
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.
Стр. 52из 81 ABS ITT Mk 20 IE On Board Diagnostic (OBD) program

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Output Diagnostic Test Mode (DTM)

Note:

All functions which could previously be
performed with V.A.G 1551 can also be
performed with the tester VAS 5051.

The pump motor and the correct functioning of
the hydraulic circuits (allocation of brake lines to
wheel cylinders and function of valves) can be
checked via the output DTM for interchange or
leaks.

The vehicle must be raised until all wheels are
free to turn. (2nd mechanic required to rotate
wheels)

The -C- key can be used to exit the test
sequence at any time.

After depressing the brake pedal several times
the vacuum in the brake booster will be
exhausted. Therefore more pressure must be
applied to the brake pedal in order to attain the
same fluid pressure in brake system, as that
attained with vacuum.

When vacuum in brake booster is exhausted
wheels may not lock; start engine and build-up
vacuum in brake booster.
Стр. 54из 81 ABS ITT Mk 20 IE On Board Diagnostic (OBD) program

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Example:
Indicated on V.A.G 1551 display during output
Diagnostic Test Mode (DTM):
(e.g. front left wheel, FL)

Output Diagnostic Test Mode -
IFL: VBAT OFL: 0V Wheel FL locked
IFL = Inlet valve Front Left
VBAT = Voltage Battery; Voltage at valve
OFL = Outlet valve Front Left
0V = 0 Volt; No voltage at valve
Locked/free = Wheel condition; must be
checked by 2nd mechanic if required

Output Diagnostic Test Mode -
EDL valves/Hyd-P: VBAT Wheel FL/FR
locked
Hydr-P = Hydraulic pump
Стр. 55из 81 ABS ITT Mk 20 IE On Board Diagnostic (OBD) program