1998 VOLKSWAGEN JETTA Service Manual

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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
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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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Read measured value block
125 Display group number: 125
Engine
1 AWD
1 Gear.
1
Indicated on display (example)

Vacant

Data bus connection for transmission
1)

1 Data bus connection is available.
0 Data bus connection is not available.3)

Data bus for all-wheel drive2)
1 Data bus connection is available.
0 Data bus connection is available.

Data bus for engine

1 Data bus connection is available.
0 Data bus connection is not available.
1) Vehicles with automatic transmission only.

Incorrect transmission control module or incorrect transmission control module coding.

Transmission control module faulty.
Repair Group 01 for relevant transmission code.
2) All-wheel drive vehicles with Haldex coupling only.
3) Data bus connection is interrupted or data bus wires are interchanged.
Electrical Wiring Diagrams, Troubleshooting & Component Locations binder.
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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.
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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
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- Connect V.A.G 1551 Scan Tool.

- Switch ignition on.

- Press key -1- for "Rapid data transfer" operating
mode.

- Select brake electronics (address word 03);
Page 01
-23
Rapid data transfer Q
03 - Brake electronics Indicated on display
Note:
During the next work steps the ABS warning light -
K47- flashes. - Confirm entry with key Q.
- Read off control module version in V.A.G 1551
display.
-
Press key.
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Rapid data transfer HELP
Select function XX Indicated on display
- Press keys 0 and 3
Rapid data transfer Q
03 - Out
put Diagnostic Test Mode
Indicated on display
- Confirm entry with key Q.
ABS hydraulic pump -V64- must run.
Output Diagnostic Test Mode
-
ABS hydraulic pump - V64
Indicated on display
-
Press key.
Output Diagnostic Test Mode
-
Operate brakes
Indicated on display
- Operate brake pedal.
-
Press key.
Output Diagnostic Test Mode
-
IFL: 0V OFL: 0V Wheel FL locked
Indicated on display
Note:
If the wheel does not lock, there is a
possibility that there is a malfunction in the
mechanical/hydraulic part of the brake
system. - Indicate to 2nd mechanic which wheel
requires turning by hand.
Стр. 57из 81 ABS ITT Mk 20 IE On Board Diagnostic (OBD) program