Part 3
Checking cable and component
Checking the fault cause
Check the fault cause as follows:
1. Ignition off
2. Disconnect the MOST connector from the multimedia module (MMM)
3. Connect the MOST cable to special tool 951 2867 MOST instrumentation 951 2867 MOST Instrumentation
4. Ignition on
5. Activate the infotainment system
6. Check that the communication on the MOST network is functioning by reading off the status of the MOST locked parameter for at least 30 seconds. The parameter indicates whether the MOST network is closed and communication possible Click the VCT2000 symbol to read off the status of the MOST network.
7. If the parameter displays that the MOST network is not correctly connected, check the receiving control module in the same way as above.
The communication on the MOST network is working if the menu text is displayed. If this is the case, the fault cause is in the multimedia module (MMM). Continue the fault-tracing by checking the component.
The communication on the MOST network is not working if the menu text is not displayed. The fault cause is then in the MOST cable for the next control module. Continue the fault-tracing by checking the fiber optic cable.
Checking cable
- Check the MOST connection. Check for dirt, loose connections and damage
- Replace the MOST cable if no fault is found in the MOST terminal.
Checking the component
- Check the power supply and the ground terminal for the multimedia module (MMM)
- Check the MOST connection. Check for dirt, loose connections and damage
- Replace the multimedia module (MMM) if no fault is found.
Remedy as necessary.
Other information:
- Multimedia module (MMM), replacing Multimedia Module (MMM), Replacing
- Checking the voltage / ground terminal Checking Supply Voltage/Ground Terminal, Multimedia Module (MMM)
- Signal specification Signal Description, Multimedia Module (MMM)
- Fiber optic cable harness, repairing Fiber Optic Cable Harness, Repairing
- Optical wiring harness check Wires
- Location of components Component Location, Infotainment
Continue - Verification
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Checking cable and component
- Ignition off
- Disconnect the MOST cable connector from the infotainment control module (ICM)
- Ignition on
- Activate the infotainment system.
Check visually whether the infotainment control module (ICM) is emitting light from the MOST connector.
The control module is defective if the infotainment control module (ICM) is not emitting light.
If the infotainment control module (ICM) is transmitting light, the fault is in the MOST cable for the next control module.
Check the MOST connection. Check for dirt, loose connections and damage.
Replace the MOST cable if no fault is found in the MOST terminal.
Remedy as necessary.
Other information:
- Infotainment control module (ICM), replacing Infotainment Control Module (ICM), Replacing
- Fiber optic cable harness, repairing Fiber Optic Cable Harness, Repairing
- Location of components Component Location, Infotainment
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 infotainment system and select the radio.
Check whether there is sound from the radio in the loudspeakers.
Is the sound of the radio coming through the loudspeakers?
Yes - VERIFIED
No - VERIFICATION FAILED
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VERIFIED - FAULT FOUND
VERIFICATION FAILED - Fault-tracing information
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Fault-tracing information
Attempt New Test - Checking the wiring and component
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Checking the cable and component
Checking the fault cause
Check the fault cause as follows:
1. Ignition off.
2. Unplug the MOST-connector from Accessory USB unit (AUU).
3. Connect the MOST cable to special tool: 951 2867 MOST instrumentation 951 2867 MOST Instrumentation
4. Ignition on.
5. Activate the infotainment system.
6. Check that the communication on the MOST-net works by reading out the status for the parameter MOST locked for at least 30 seconds. The parameter indicates whether the MOST network is closed and communication possible. Click on the VCT2000 symbol to obtain a MOST network status reading.
7. If the parameter shows that the MOST network is not closed, check the receiving control module in the same way as described above.
The communication on the MOST network is working if the menu text is displayed. The cause of the fault is in the Accessory USB unit (AUU). Continue the fault-tracing by checking the component.
The communication on the MOST network is not working if the menu text is not displayed. The fault cause is then in the MOST cable for the next control module. Continue the fault-tracing by checking the fiber optic cable.
Checking the cable
- Check the MOST connection. Check for dirt, loose connections and damage.
- Replace the MOST cable if no fault is found in the MOST terminal.
Checking the component
- Check the audio module (AUD) power supply and ground connection for the Accessory USB unit (AUU).
- Check the MOST connection. Check for dirt, loose connections and damage.
- If no fault is found, replace the Accessory USB unit (AUU).
Remedy as necessary.
Other information
- Universal bus module (USB), L.H.D Universal Serial Bus (USB) Module
- Checking the supply voltage/ground terminal Checking Voltage/Ground Terminal, Accessory USB Unit (AUU)
- Signal specification Signal Specification, Accessory USB Unit (AUU)
- Fiber optic cable harness, repairing Fiber Optic Cable Harness, Repairing
- Optical wiring harness check Wires
- Location of components Component Location, Infotainment
Continue - Verification
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