Part 2

Fault-tracing

Checking phone module (PHM)

Checking fuses
Check that the fuse for the function in question is intact.
Replace the fuse if it is damaged.
For information about fuses, see the wiring diagram.

Checking the fault cause
Check the fault cause as follows:
1. Ignition off.
2. Disconnect the MOST connector from the relevant control module.
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.
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. Then the malfunction cause is in the control module in question. 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 voltage feed and ground connection for the control module in question.
- Check the MOST connection. Check for dirt, loose connections and damage.
- Replace the control module if no fault is found.
Click on the VCT2000 symbol to read out status on MOST-net.

Note! To read off the open circuit position again and verify that the MOST loop is closed or if there is another open circuit in the loop, the MOST system must complete a complete ring break-diagnosis as previously in the fault tracing (i.e. the MOST system is supplied with voltage after having been without power).

Remedy as necessary.

Other information
- Diagnostic Instructions - Fibre Optic Cable Diagnostic Instructions - Fibre Optic Cable
- Phone Module (PHM) Service and Repair
The following links apply to Phone Module (PHM), later version.
- Signal specification Signal Specification, Phone Module (PHM)
- Checking the supply voltage/ground terminal Checking Supply Voltage/Ground Terminal . Phone Module (PHM)
- Diagnostic Instructions - Fibre Optic Cable Diagnostic Instructions - Fibre Optic Cable
- Phone Module (PHM) Service and Repair









Continue - Verification

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Checking the Remote Digital Audio Receiver (RDAR)

Checking fuses
Check that the fuse for the function in question is intact.
Replace the fuse if it is damaged.
For information about fuses, see the wiring diagram.

Checking the fault cause
Check the fault cause as follows:
1. Ignition off.
2. Disconnect the MOST connector from the relevant control module.
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.
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. Then the malfunction cause is in the control module in question. 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 voltage feed and ground connection for the control module in question.
- Check the MOST connection. Check for dirt, loose connections and damage.
- Replace the control module if no fault is found.
Click on the VCT2000 symbol to read out status on MOST-net.

Note! To read off the open circuit position again and verify that the MOST loop is closed or if there is another open circuit in the loop, the MOST system must complete a complete ring break-diagnosis as previously in the fault tracing (i.e. the MOST system is supplied with voltage after having been without power).

Remedy as necessary.

Other information
- Checking the supply voltage/ground terminal Checking Voltage/Ground Terminal, Remote Digital Audio Receiver (RDAR)
- Signal specification Pinout Values and Diagnostic Parameters
- Diagnostic Instructions - Fibre Optic Cable Diagnostic Instructions - Fibre Optic Cable
- Location of components Component Location, Remote Digital Audio Receiver (RDAR)
- Satellite radio control module Satellite Radio Control Module









Continue - Verification

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Checking the Digital Audio Broadcast Module (DABM)

Checking fuses
Check that the fuse for the function in question is intact.
Replace the fuse if it is damaged.
For information about fuses, see the wiring diagram.

Checking the fault cause
Check the fault cause as follows:
1. Ignition off.
2. Disconnect the MOST connector from the relevant control module.
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.
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. Then the malfunction cause is in the control module in question. 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 voltage feed and ground connection for the control module in question.
- Check the MOST connection. Check for dirt, loose connections and damage.
- Replace the control module if no fault is found.
Click on the VCT2000 symbol to read out status on MOST-net.

Note! To read off the open circuit position again and verify that the MOST loop is closed or if there is another open circuit in the loop, the MOST system must complete a complete ring break-diagnosis as previously in the fault tracing (i.e. the MOST system is supplied with voltage after having been without power).

Remedy as necessary.

Other information
- Diagnostic Instructions - Fibre Optic Cable Diagnostic Instructions - Fibre Optic Cable









Continue - Verification

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Checking Television Module (TVM).

Checking fuses
Check that the fuse for the function in question is intact.
Replace the fuse if it is damaged.
For information about fuses, see the wiring diagram.

Checking the fault cause
Check the fault cause as follows:
1. Ignition off.
2. Disconnect the MOST connector from the relevant control module.
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.
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. Then the malfunction cause is in the control module in question. 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 voltage feed and ground connection for the control module in question.
- Check the MOST connection. Check for dirt, loose connections and damage.
- Replace the control module if no fault is found.
Click on the VCT2000 symbol to read out status on MOST-net.

Note! To read off the open circuit position again and verify that the MOST loop is closed or if there is another open circuit in the loop, the MOST system must complete a complete ring break-diagnosis as previously in the fault tracing (i.e. the MOST system is supplied with voltage after having been without power).

Remedy as necessary.

Other information
- Location of components Component Location, Television
- Signal specification Signal Specification
- Receiver TV TV Receiver, Replacing









Continue - Verification

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Checking rear seat entertainment module (RSE)

Checking fuses
Check that the fuse for the function in question is intact.
Replace the fuse if it is damaged.
For information about fuses, see the wiring diagram.

Checking the fault cause
Check the fault cause as follows:
1. Ignition off.
2. Disconnect the MOST connector from the relevant control module.
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.
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. Then the malfunction cause is in the control module in question. 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 voltage feed and ground connection for the control module in question.
- Check the MOST connection. Check for dirt, loose connections and damage.
- Replace the control module if no fault is found.
Click on the VCT2000 symbol to read out status on MOST-net.

Note! To read off the open circuit position again and verify that the MOST loop is closed or if there is another open circuit in the loop, the MOST system must complete a complete ring break-diagnosis as previously in the fault tracing (i.e. the MOST system is supplied with voltage after having been without power).

Remedy as necessary.









Continue - Verification

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