Checking Cable And Component
If the result of the ring break diagnostic is POOR, the infotainment control module (ICM) is receiving a signal on the MOST network. However it is unable to decode the signals because the luminance of the signals is too weak or the signals are distorted.
If the result from the ring break diagnostic is OK, the fault is intermittent.
Fault-tracing using the ring break diagnostic assumes that the fault is permanent or active when the test is run, i. e. the system is powered having been off.
HINT: If diagnostic trouble code (DTC) ICM-DC01 is intermittent, read off the status of the ring break diagnostic from the frozen values in Vehicle communication.
HINT: Note that the AM/FM tuner module (AFM) and the traffic message channel module (TMC) are not normally included in a ring break diagnostic if the fuse is not removed. This means that the position of the open-circuit moves two steps backwards in the MOST network.
HINT: On fully equipped vehicles, if the open-circuit position is 5, this may be because of:
- Multimedia module (MMM)
- The fiber optic cable between the multimedia module (MMM) and the AM/FM tuner module (AFM)
- AM/FM tuner module (AFM)
- The fiber optic cable between the AM/FM tuner module (AFM) and the traffic message channel module (TMC)
- Traffic message channel module (TMC)
- The fiber optic cable between the traffic message channel module (TMC) and the audio module (AUD).
Check the communication on the MOST network by bypassing the control modules one by one on the MOST network as follows:
- Ignition off
- Disconnect the MOST connector from the relevant control module
- Connect the MOST cable to special tool 9512867
- Ignition on
- Activate the infotainment system
- 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.
If the communication on the MOST network is stable when a control module is disconnected, check the power supply and the ground terminal on the relevant control module. Check for intermittent faults. Try replacing the component if no fault is found.
Click the VCT2000 symbol to read off the status of the MOST network.
- Continue
See: VERIFICATION
Select the control module to be checked from the list.
1. Media player module (MPM).
See: CHECKING CABLE AND COMPONENT
2. Phone module (PHM)
See: CHECKING THE CABLE AND COMPONENT, PHONE MODULE (PHM)
3. Subwoofer module (SUB)
See: CHECKING THE CABLE AND COMPONENT, SUBWOOFER MODULE (SUB)
4. Global positioning system module (GPS)
See: CHECKING THE CABLE AND COMPONENT, GLOBAL POSITIONING SYSTEM MODULE (GPS)
Select the control module to be checked from the list.
1. Audio module (AUD)
See: CHECKING THE CABLE AND COMPONENT, AUDIO MODULE (AUD)
2. Traffic message channel module (TMC)
See: CHECKING THE CABLE AND COMPONENT, TRAFFIC MESSAGE CHANNEL MODULE (TMC)
3. AM/FM tuner module (AFM)
See: CHECKING THE CABLE AND COMPONENT, AM/FM TUNER MODULE (AFM)
4. Multimedia module (MMM)
See: CHECKING CABLE AND COMPONENT
5. Infotainment control module (ICM)
Checking the fault cause
Check the fault cause as follows:
- Ignition off
- Disconnect the MOST connector from the media player module (MPM)
- Connect the MOST cable to special tool 9512867
- Ignition on
- Activate the infotainment system
- 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
- 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 media player module (MPM). 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 media player module (MPM)
- Check the MOST connection. Check for dirt, loose connections and damage
- Replace the media player module (MPM) if no fault is found.
Remedy as necessary.
Click the VCT2000 symbol to read off the status of the MOST network.
Other information
- See: MEDIA, COMMUNICATION AND NAVIGATION - REMOVAL, REPLACEMENT AND INSTALLATION (544 BODY)
- See: CHECKING THE SUPPLY VOLTAGE/GROUND TERMINAL
- See: SIGNAL SPECIFICATION
- See: DIAGNOSTIC INSTRUCTIONS - FIBER OPTIC CABLE
- See: FIBER OPTIC CABLE HARNESS, REPAIRING
- For information about location and order of control modules in the MOST network, See: LOCATION OF COMPONENTS
- Continue
See: VERIFICATION
- 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
- See: INFORMATION AND ENTERTAINMENT DISPLAY
- See: FIBER OPTIC CABLE HARNESS, REPAIRING
- For information about location and order of control modules in the MOST network, See: LOCATION OF COMPONENTS
- Continue
See: VERIFICATION
Checking the fault cause
Check the fault cause as follows:
- Ignition off
- Disconnect the MOST connector from the multimedia module (MMM)
- Connect the MOST cable to special tool 9512867
- Ignition on
- Activate the infotainment system
- 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
- 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.
Click the VCT2000 symbol to read off the status of the MOST network.
Remedy as necessary.
Other information
- See: CONTROL MODULE INFORMATION AND ENTERTAINMENT
- See: CHECKING THE SUPPLY VOLTAGE/GROUND TERMINAL
- See: SIGNAL SPECIFICATION
- See: FIBER OPTIC CABLE HARNESS, REPAIRING
- See: DIAGNOSTIC INSTRUCTIONS - FIBER OPTIC CABLE
- For information about location and order of control modules in the MOST network, See: LOCATION OF COMPONENTS
- Continue
See: VERIFICATION