light AUDI A4 1998 B5 / 1.G Airbag Service OBD Workshop Manual

interior switches when an airbag is triggered.
Also, interior lighting is switched on. The "crash
signal" can be checked using the Output
Diagnostic Test Mode page 01
-44
.
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01-6

1999 vehicles : from VIN 8D XA 200 001 Airbag system includes: side airbag, passenger-
side airbag, two front seat belt tensioners, two
front side airbags, two or three rear seat belt
tensioners and side curtain airbags. In a crash
situation, these are ignited centrally by the airbag
control module -J234- when specified triggering
criteria are met.
In a crash situation, the control module sends a
crash signal to the central locking control
module. This function is a passive safety feature.
It releases door locks and the rear lid lock via the
central locking system if an airbag and/or belt
tensioner is triggered. Also, inside door lock
switches are blocked and interior lighting is
switched on. The "crash signal" can be checked
using output Diagnostic Test Mode (DTM)
page 01
-44
.
When the airbags and/or belt tensioners are
deployed, the control module will record the DTC
"Crash data stored."
Airbag control module -J234- must be replaced
following:

The 1st driver-side/passenger-side airbag
deployment.
The 3rd time front seat belt tensioners and/or
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01-7

All vehicles
The control module detects malfunctions and
errors in the airbag system and stores them in
permanent memory.
After the ignition is switched on, the airbag
Malfunction Indicator Lamp (MIL) -K75- lights for
about 4 seconds and then goes out.

If the airbag Malfunction Indicator Lamp (MIL) -
K75- does not go out after approximately 4
seconds, the voltage supply for the airbag
control module -J234- is not OK. Check DTC
memory page 01
-11
.

If the airbag Malfunction Indicator Lamp (MIL) -
K75- goes out after 4 seconds and then lights
again, either the control module is not coded,
an incorrect control module has been installed
or a malfunction is present. Check DTC
memory page 01
-11
.

CAUTION!

Wiring must only be checked visually!
Do not perform an electrical continuity check
or circuit analysis!

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obtained by pressing the VAG1551 Scan Tool
(ST) HELP button.
The button is used to advance through the
program sequence.

- Switch printer on by pressing PRINT button
(indicator lamp in button lights up).

- Press button -1- to select "Rapid data transfer"
operating mode 1.
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01-11

Check DTC Memory (scan tool function
02)


Note:
The DTC display information is updated only
when initiating the On Board Diagnostic (OBD) or
"Erase DTC Memory" function 05.

- Switch printer on by pressing PRINT button
(indicator lamp in button lights up).

Carrying out "Check DTC Memory" function
02
Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -2- to select "Check DTC Memory" function 02.
Rapid data transfer
Q
02 - Check DTC Memor
y

Indicated on display
- Press -Q- button to confirm input.
X DTC recognized

Indicated on display (number of stored Diagnostic Trouble Codes, DTCs).
or:
No DTC recognized

If the message "No DTC recognized" is displayed, the program can be
returned to the starting point by pressing the button.
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01-13
Diagnostic Trouble Code (DTC) table, airbag system

Notes:

In the following table, all the possible malfunctions that can be recognized by the airbag control module -J234- are listed
according to their DTC code numbers. Existing malfunctions will be printed with their 5-digit DTC only if the VAG1551
printer is switched on.
If a malfunction occurs persistently, the airbag Malfunction Indicator Lamp (MIL) -K75- will light up and remain lit until the
malfunction is repaired and the DTC memory has been erased.
If a malfunction occurs only occasionally or if the DTC memory is not erased after a malfunction is repaired, the
malfunction will be displayed as a sporadic malfunction. Such malfunctions are identified by the letters "/SP" to the right on
the VAG1551 display and will cause -K75- to light up continuously.
Before replacing a component shown as malfunctioning, check the wiring to the component for short or open circuit
according to the wiring diagram.
The three digit malfunction type number appearing next to the DTC is a data code which can be disregarded.
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01-38

DTC


VAG 1551 scan tool display
Possible cause
Corrective action
01578
Wng.Light for Airbag Off,Pass. Side-
K145
Short circuit to B+
Wiring damagedAirbag control module -J234-
faulty Electrical Wiring Diagrams,
Troubleshooting & Component Locations
binder - Repair wiring according to wiring diagram
- Replace airbag control module -J234-
01578
Wng.Light for Airbag Off,Pass. Side-
K145
Open/Short circuit to ground
Wiring damagedWarning light for airbag off,
passenger side -K145- faulty Airbag control module -J234-
faulty Electrical Wiring Diagrams,
Troubleshooting & Component Locations
binder - Repair wiring according to wiring diagram
- Replace warning light -K145-
- Replace airbag control module -J234-
01588
Ign. for Side Curtain Airbag, Driver Side-
N251Resistance value too large
Open circuit in wiringDriver-side side curtain airbag
faulty Airbag control module faulty - Repair open circuit.
- Replace driver-side side curtain airbag.
- Replace airbag control module -J234-.
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01-44

Output Diagnostic Test Mode (scan tool
function 03) (vehicles 1997 1998)

The Output Diagnostic Test Mode is used to
check operation of the crash response system.
When airbags are triggered, the central locking
system unlocks the doors and simultaneously
blocks internal switches. Emergency flashers and
interior lights are switched on.

Notes:
Before initiating the Output Diagnostic Test
Mode, switch central locking system to "closed"
by operating internal switch.

Carrying out "Output Diagnostic Test Mode"
function 03 Rapid data transfer
HELP
Select function XX

Indicated on display
- Press buttons -0- and -3- to select "Output Diagnostic Test Mode"
function 03.
Rapid data transfer
Q
03 - Output Dia
gnostic Test Mode

Indicated on display
- Press -Q- button to confirm input.
Output Diagnostic Test Mode Signal: Open central locking system

Indicated on display
The central locking system must switch to "open."
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Emergency flashers and interior lights switch on.
- Operate internal switch.
Central locking must switch back to "closed."
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01-46

Output Diagnostic Test Mode (scan tool
function 03) (vehicles 1999 )


Vehicles up to calendar week (KW) 18.99
Output Diagnostic Test Mode (DTM) is used to
check the operation of the crash response
system. When airbags are triggered, the central
locking system switches immediately to "open"
and the inside door lock switches are blocked.
Emergency flashers and interior lights are
switched on.

Notes:

Before initiating output Diagnostic Test Mode
(DTM), set the central locking system to
"closed" by operating the interior switch.
Set interior switch to "door contact" position.
After output DTM is initiated, central locking
cannot be operated until the DTC memory of
the central locking control module is erased.

Carrying out "Output Diagnostic Test
Mode" (function 03)
Rapid data transfer
HELP
Select function XX

Indicated on display
-
Press buttons -0- and -3- to select "Output Diagnostic Test Mode"
Pa
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