Checking the Audio / Carphone Switch

Checking the audio / carphone switch

Checking components




- Ignition on.
Activate and read off the status of the buttons in the audio / carphone switch.
If the readings give a correct result, the fault is not in the steering wheel module (SWM).





Was the audio / carphone switch status OK?

Yes - No Fault Found

No - Car equipment

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Car equipment

Is the car equipped with the Road Traffic Information (RTI) system?

Yes - Checking components and wiring

No - Checking components and wiring

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Checking components and wiring




- Ignition off
- Disconnect the RTI switch
- Ignition on.
Activate and read off the status of the buttons in the audio / carphone switch.
If the readings give a correct result, the fault is in the RTI switch.

Other information:
- To access the RTI switch, see RTI switch RTI Switch.





Was the audio / carphone switch status OK?

Yes - Fault Found

No - Checking components and wiring

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Checking components and wiring




- Ignition off
- Disconnect the audio / carphone switch by disconnecting the lower connector on the audio / carphone switch
- Ignition on.
Activate the buttons. Read off the status of the buttons in the cruise control switch
If the readings give a correct result, the fault is in the audio / carphone switch.

Other information:
- To access the audio / carphone switch, see the relevant service procedure.





Was the status of the cruise control switch OK?

Yes - Fault Found

No - Checking components and wiring

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Checking components and wiring




- Ignition off
- Disconnect the audio / carphone wiring by disconnecting the lower connector on the cruise control switch
- Ignition on.
Activate the buttons. Read off the status of the buttons in the cruise control switch
If the readings give a correct result, the fault is in the wiring between the audio / carphone switch and the cruise control switch.

Other information:
- To access the cruise control switch, see the relevant service procedure.





Was the status of the cruise control switch OK?

Yes - Fault Found

no - Checking components and wiring

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Checking components and wiring
Check the voltage between terminals #B1 and #B3. Voltage must be approximately 12 V.
Check the voltage between terminals #B2 and #B3. Voltage must be approximately 5 V.
Check the voltage between terminal #B3 and the battery negative terminal. Voltage must be approximately 0 V.
If the above readings are OK, the fault is in the cruise control switch.

Other information:
- To connect the breakout box, see Connecting the breakout box Connecting the Breakout Box, Steering Wheel Module (SWM).









Was a fault detected?

Yes - Fault Found

No - No Fault Found

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