Description of On Board Diagnostics
Airbag System BTU (Basic Triggering Unit) With Side Airbag, On Board Diagnostic (OBD)
General information
The airbag system features the following:
Driver's airbag, front passenger airbag, two front belt tensioners, two front side airbags, two rear side airbags and two or three rear belt tensioners. In a crash situation, these systems are centrally ignited by the airbag control module -J234 on exceeding specified triggering criteria.
Ignition of the airbag and/or belt tensioners causes the DTC "Crash data stored" to be entered in the control module. The control module is to be replaced.
Irrespective of the nature and intensity of the accident, the airbag control module transmits a "Crash signal" to the central locking control module. This function is a passive safety feature. On airbag triggering, it uses the central locking function to unlock the door locks and trunk lid/tailgate lock and to block the internal switch. The passenger compartment lighting is switched on. The "Crash signal" is to be checked using the Output Diagnostic Test Mode function. Vehicles Up to 18.99
Coding is to be performed when commissioning a new control module. Programming and Relearning
Vehicles from 36.98 on:
The airbag system features the following:
Driver's airbag, front passenger airbag, two front belt tensioners, two front side airbags, two rear side airbags, head airbag and two or three rear belt tensioners. In a crash situation, these systems are centrally ignited by the airbag control module -J234 on exceeding specified triggering criteria.
Ignition of the airbag and/or belt tensioners causes the DTC "Crash data stored" to be entered in the control module.
The airbag control module -J234 is to be replaced following
- 1st triggering of driver's/front passenger airbag
- 3rd triggering of front belt tensioners and/or side airbags
Up to calendar week 36.98 the crash telegram cannot be erased using the VAG 1551 Scan Tool (ST); on vehicles with airbag 8 after the third triggering.
Irrespective of the nature and intensity of the accident, the airbag control module transmits a "Crash signal" to the central locking control module and - as of calendar week 18.99 - to the engine control module. This function is a passive safety feature. On airbag triggering, it uses the central locking function to unlock the door locks and trunk lid/tailgate lock and to block the internal switch. It also switches on the passenger compartment lighting. The engine control module shuts off the fuel supply. The "Crash signal" is to be checked using the Output Diagnostic Test Mode function. Vehicles From 18.99 on
Coding is to be performed when commissioning a new control module.
Programming and Relearning
On Board Diagnostic (OBD) functions
Possible functions:
02 - Check DTC Memory
03 - Output Diagnostic Test Mode
05 - Erase DTC Memory
06 - End Output
07 - Code Control Module
08 - Read Measuring Value Block
All models:
The control module detects faults and malfunctions in the airbag system and stores them in a non-volatile memory.
After switching on the ignition, the airbag warning lamp -K75 lights for approx. 4 s and then goes out again.
- If airbag warning lamp -K75 does not go out after approx. 4 s, supply voltage for airbag control module -J234 is not OK. Check DTC Memory.
- If airbag warning lamp -k75 goes out and comes back on again, this indicates that control module has not been coded, that an incorrect control module has been fitted or that a fault has occurred. Check DTC Memory.
WARNING!
Wiring is only to be subjected to visual inspection.
Never perform continuity tests or measurements in ignition circuits.
Always switch off ignition before checking wiring.
On Board Diagnostic (OBD) functions
Possible functions:
02 - Check DTC Memory
03 - Output Diagnostic Test Mode
05 - Erase DTC Memory
06 - End Output
07 - Code Control Module
08 - Read Measuring Value Block