Checking the Wiring and Connectors (Melbus)

Checking the wiring and connectors (Melbus)

Fault-tracing information
The audio module (AUM) communicates with other accessories, such as external CD changers, TV receiver and road traffic information (RTI), via a serial DIN cable (Melbus).
A fault in the serial communication (for example faults on the cable harness or connector) can affect the functionality of all accessories.
Depending on the accessories installed on the vehicle the following faults may occur, separately or together:
- The integrated CD player does not function and cannot be found using the SOURCE button
- The external CD player does not function and cannot be found using the SOURCE button
- TV reception does not function
- Problems with road traffic information module (RTI).

Probable fault causes
- Fault in the DIN cable between the audio module (AUM) and the external CD changer, TV receiver and road traffic information (RTI)
- Fault in the DIN cable between the audio module (AUM) and the external amplifier
- Fault in the connectors or terminals.

Continue - Checking connectors and wiring

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Checking connectors and wiring




- Ignition on.
Check the serial cable harness between the audio module (AUM) and the external CD changer, TV receiver and road traffic information (RTI). Check by removing each DIN connector for the accessories in turn. Check that the other functions operate after each connector is removed (for example that the internal CD player functions and can be selected using the SOURCE button).
Check the DIN connectors. Check for bent or pressed in pins.
When the functions reappear the fault is probably in the wiring or connector that was removed.
Remove the DIN connectors from the accessories in the following order:
1. External CD changer
2. TV receiver
3. Road traffic information module (RTI).
Check the DIN cable and connector between the audio module (AUM) and the external amplifier. Remove the connector and check if the functions operate.
Check the connectors in the control modules and accessories. Check for intermittent faults. Try to replicate the fault by twisting and turning the connections.
Remedy as necessary.





Was a fault detected?

Yes - FAULT FOUND

No - No Fault Found

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