| Function of the airbag system |
| The airbag System comprises: |
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| Sensors for side impact |
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| Driver and front passenger side airbags |
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| Belt tensioners for driver and front passenger |
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| Key switch for the front passenger seat airbag (special accessory for vehicles of model year 03) ? |
| Depending on the vehicle equipment and control unit used → Chapter the vehicles may be fitted with: |
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| electronically activated belt tensioners → Note |
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| mechanically activated belt tensioners → Note |
| 1)
| Inspected by self-diagnosis; ignited by the airbag control unit -J234-. |
| 2)
| Not inspected by self-diagnosis; ignited independently of the airbag control unit -J234-. |
| If programmed values are exceeded the airbag CU -J234- activates the release of the airbag units and belt tensioners. |
| The operation of the airbag units can be activated or blocked via the self-diagnosis → Chapter. |
| The switching on and off operations are undertaken by means of the key switch for the front passenger airbag if the vehicle is fitted with such a key switch. |
| If the airbag units on the front passenger side are deactivated, faults relating to airbag deactivation are stored in the fault memory and, after the airbag units are subsequently re-activated, the faults are automatically erased from the fault memory (only for vehicles which do not have a key switch for the front passenger airbags). |
| When igniting the driver and front passenger front airbags with belt tensioners the fault “crash data stored” is entered in the fault memory and the control unit must be replaced with a new original part. |
| If the control unit detects a side impact it ignites the side airbag unit and the belt tensioner on the impact side. The fault “crash data side airbag DS stored” or “crash data side airbag FPS stored” is entered in the fault memory. These data can be erased 3x at the most, after which the control unit must be replaced with a new original part. |
| If the vehicle is equipped with mechanical belt tensioners, these belt tensioners are ignited independently of the signal from the airbag CU -J234-. |
| Code the new CU when it is first put into service → Chapter. |
| If airbag units or belt tensioners are ignited, the airbag CU sends a crash signal to the electrical system control unit. When the airbag unit is released: |
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| the interior lighting is switched on |
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| the hazard warning system is activated |
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| the fuel pump is deactivated |
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| the electrical steering force assistance is switched off |
| Check the control unit signal using actuator diagnosis → Chapter. |
| The control unit of airbag -J234- is located in the front section of the centre console. |
| The control unit -J234- detects faults and malfunctions in the airbag system and stores them in the fault memory. |
| Faults due to a temporary line interruption or loose contact are also stored. These faults are displayed as sporadic faults “SP”. |
| After the ignition is switched on, the airbag warning light -K75- comes on for about 4 seconds. If the warning light then flashes for a further 12 seconds this indicates that the front passenger airbag unit has been electronically blocked (only for vehicles which do not have a key switch for the front passenger airbag). |
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| If warning lamp -K75- does not go out after 4 seconds there is a fault. Interrogate the fault memory → Chapter. Erase fault memory after fault elimination → Chapter. |
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| If the warning lamp -K75- remains lit the airbag control unit -J234- is not coded. The airbag control unit -J234- must be coded → Chapter. |
| Initiate self-diagnosis at the start of fault finding and interrogate the fault memory using the diagnostic device -V.A.G 1552-, -V.A.G 1551- or -VAS 5051-. |
| Faults in other control units may be stored (e.g. disconnected plug connections) during testing and fitting. This is why the fault memories of all control units must be interrogated and then erased. |
| Therefore it is necessary to: |
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| Enter address word 00 “Automatic Test Sequence”. Vehicle system tester -V.A.G 1552- checks the fault memory of all vehicle systems. |
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| If the corresponding CU responds with its identification number, the number of faults and type or “No fault recognized” appears in the display. |
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| Eliminate possible faults and erase fault memory. |
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Note
DANGER!