Checking The Cable And Component
Troubleshooting with ring break diagnosis requires that the malfunction is permanent or active while the test is running (when the system is supplied with voltage after having been without voltage)
If the result from the ring break diagnostic is OK, the fault is intermittent. Skip remaining Troubleshooting by selecting Continue.
If the result of the ring break diagnostic is poor signal , 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 ring break diagnosis is diagnosis multimaster this indicates that one or several control modules consider themselves master node on the MOST-net.
HINT: If diagnostic trouble code ICM-U1A1587 is generated intermittently, obtain a ring break diagnosis status reading in Vehicle Communication frozen values.
Bypass the control modules on the MOST network one at a time to check network communication. Proceed as follows:
- Ignition off.
- Disconnect the MOST connector from the relevant control module.
- Connect the MOST cable to special tool: see 9512867
- Activate the infotainment system.
- Check that the communication on the MOST-net works by reading out the status for the parameter MOST locked for at least 30 seconds. Click on the VCT2000 symbol in VIDA (Volvo scan tool) to read out status on MOST-net. The parameter indicates whether the MOST network is closed and communication possible.
If communication on the MOST-net is stable when a control module is disconnected, check voltage feed and ground connection for the control module in question for intermittent malfunctions. Try replacing the component if no fault is found.
- Continue
Refer to VERIFICATION