Incorrect Signal

Incorrect signal

Checking fuse and voltage feed




- Ignition on
Phone module (PHM) is supplied with voltage via a fuse from central electronic module (CEM).
Check if the fuse for the phone module (PHM) is half-blown by testing with a new fuse.

Hint: A half-blown fuse can give intermittent malfunctions.

Check the voltage feed to the phone module (PHM) by:
- measuring the voltage between the phone module's connector A #5 (#5) and A #6 (#6)
- measuring the battery voltage.
If the difference is greater than 2.5 V between the control module's feed voltage and the battery voltage, the malfunction is in the feed cable.
If the difference is less than 2.5 V there may be an internal malfunction in the phone module (PHM).
Remedy as necessary.

Other information:
- For further information about the fuses and relays, see wiring diagram.
- Connecting the breakout box Connecting the Breakout Box, Phone Module (PHM)
- Signal specification Signal Specification, Phone Module (PHM)
- Location of components Locations
- Handset, replacing Handset, Replacing
- Checking wiring and terminals Checking Wiring and Terminals









Select Continue.

Continue - Verification

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Verification




Verification

Hint: After carrying out the repair, check that the fault has been remedied.








- Ignition off
- Reinstall the connectors, components etc.
- Ignition on
- Activate the carphone.
Make a call so that both the handset and the hands-free system are used. See instruction manual.
Ignition off.
Ignition on.
Read off the diagnostic trouble codes (DTCs).
Check that the relevant diagnostic trouble code (DTC) has switched status from permanent to intermittent fault.





Has the status of the diagnostic trouble code (DTC) changed?

Yes - Troubleshooting procedure complete

No - Troubleshooting information

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Troubleshooting information




Information

Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.

Do you want to exit fault-tracing?

Yes - Exit Fault-tracing

No - Attempt New Test

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Attempt New Test - Checking fuse and voltage feed

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