Airbag Warning Light – Fault Code Removal

Introduction

This document describes the procedure to switch off the airbag dash light, using the KWP71 software to

interrogate the air bag ECU and clear out fault codes. This applies to a Lancia Lybra 1.9JTD but not

limited to this car maker and make. In addition, this procedure was carried out using a Windows XP OS.

The fault was cleared from the Airbag ECU but not diagnosed the cause for this fault. Further error

analysis and investigation was not fully addressed in this task and hence not documented. This was fixed

for the moment and feel confident this will solve the issue. However this may not be applicable to your

case!

This document addresses the software installation and configuration issues as it was our experience that

this is the most complicated issue to tackle. If you are a computer illiterate, you may be less prepared to

do this successfully but be patient. If you are familiar with computers, you may still have to be patient

though!

Disclaimer: this document describes the procedure carried for information only and, as such, it is

intended to be used at own risk. No liabilities are accepted for any damage or injury caused by any

errors or omissions in this manual. Use at your own risk. Airbag are safety systems and as such please

make sure your safety is properly regarded.

References

[AR1] Overall explanation about the process, Alfa Romeo Forum

http://www.alfaowner.com/Forum/alfa-147-156-and-gt/154879-kwp71-how-to-use-to-

connect-to-airbag-abs-ecus.html

[DIAG] Pin out information about OBD

http://www.freediag.org/OBD_plug_pins_and_protocols.txt

[OBD] OBD Reference and General Information

http://www.blafusel.de/obd/obd2_start.html

[K71] KWP71 software

Official homepage sourcing this software: http://autos.groups.yahoo.com/group/UniDiag/

Alternative source: http://home.wanadoo.nl/sanderqv/diag/KWP71Diag.zip

Tools

• OBD-II cable connector

• KWP71 software [K71]

Procedure

This procedure describes the step by step approach as follows:-

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Airbag Warning Light – Fault Code Removal

1) The cable of the shelf needs to be adapted so you can manage the Airbag ECU. Insert jumper

from pin 3 to pin 7 in order to read airbag information from ODB connector. Doing this provides

the ability to read out airbag error codes. BTW, doing the same for pin 1 (inserting jumper to 7)

will cause to read ABS error codes.

Figure 1: ODB-II jumper – see the red wire thought the transparency

2) Connect the OBD-II cable to a USB port on your computer, or laptop.

3) Make sure that the connection of the USB terminal into your computer is followed by the

installation of the corresponding driver (if for the first time). Also check to which COM port this

USB connection is associated (most likely you will see a small window popping up on the RHS

next to the small icons of your windows bar). It is recommended to verify the COM port and

driver activated using the Control Panel -> System -> Hardware -> Device Manager as depicted

in figure below:-

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Airbag Warning Light – Fault Code Removal

Figure 2: Configure COM port for OBD cable 1/2

It can be seen that OBD cable has taken COM5 port and one should configure the some parameters as

follows:-

Figure 3: Configure COM port for OBD cable 2/2

It is important to notice that the OBD-II cable is reading/writing out through the COM5, which is the port

to use. Also, make sure that this port is configured as follows:-

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Airbag Warning Light – Fault Code Removal

Figure 4: COM5 configuration parameters

NB: it is not mandatory to read through COM3 as it may be suggested from other sources [AR1].

4) Open (launch) the KWP71 Diagnostic software

5) Configure the KWP71 to read/write through COM5 port

6) Additional configuration parameters:-

a. Prot Sub Type: KWP81

b. ECU start address 0x00

c. For all the other parameters, check Figure 7 below

7) Connect the ODB-II into ODB car socket (it is next to the fuses box)

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Airbag Warning Light – Fault Code Removal

Figure 5: OBD socket (fuse box)

Figure 6: Overall connection layout

8) Open Com Port (successful opening should be noticed)

9) Start Comm and turn the ignition key to MAR position as soon as possible. Otherwise, a timeout

will take place!

10) The error code (5 bytes frame length) read has been the following: A7 86 91 19 2C ID

Should this be done using AlfaDiag, the following error parsing would apply:-

DTC: 0xA7

Whereas all the others are not I do not know how to)

11) Click “Read Faultcodes” button

12) Click “Clear Faultcodes” button

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Airbag Warning Light – Fault Code Removal

Figure 7: KWP71 user interface

13) At this stage, the message “Clear diagnostic faultcodes” should pop in “OK” and the airbag light

on the dash should come off.

14) Stop Comm Port

15) Close Com Port

Figure 8: Airbag light (what should not be seen any more☺☺☺☺)

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