B1228

Airbag Warning Lamp





Fault symptoms

B1227
Airbag warning lamp does not light up for 3-4 s when ignition switch is turned to ON position.

B1228
Airbag warning lamp on and central warning lamp on (only for open circuit).

Conditions
The following conditions are applicable to the respective diagnostic trouble codes:

B1227
- Short-circuit to battery positive (B+) when warning lamp is activated, e.g. when ignition switch is turned to the ON position.
- The voltage on the output is higher than 5 V for 1.25 s.

B1228
- Open circuit/shorting to ground.
- The voltage on the output is lower than 1 V or the resistance is higher than 10 K Ohms when the output is not activated.

Action

1. Check the main instrument display panel

Is the main instrument display panel live?

YES
- Go to step 2.
NO
- Continued fault diagnosis in the MIU.

2. Check the wiring




- Turn the ignition switch to the OFF position.




- Undo the connector: Main instrument display panel 20-pin connector: (540)




- Connect up test lamp 86 11 857 between B+ and pin 1 in the 20-pin connector of the main instrument display panel.




- Turn the ignition switch to the ON position.
- The test lamp should come on for 3 seconds, then go out for 0.5 seconds, and then be on.

Test results OK?

YES
- Go to step 3.
NO
- Rectify the wiring between the airbag control module, pin 6, and pin 1 of the main instrument display panel
- Go to step 4.

3. Changing a component.




- Change: The airbag lamp in the MIU.

- Go to step 4.

Test results OK?

YES
- The steps taken to rectify the fault were correct.
NO
-

4. Final check




- Clear the diagnostic trouble codes in all systems.
- Perform a driving cycle:
- Drive the car with varying engine loads and at varying engine speeds for five minutes.
- Evaluate the driving cycle:




- Check that the diagnostic trouble code has not recurred.

Test results OK?

YES
- The steps taken to rectify the fault were correct.
NO
- See before changing a control module.