Checking The Wiring And Component
The infotainment control module (ICM) has detected an open-circuit in communication on the MOST network.
The MOST network is a fiber optic ring network. This means that all control modules which are connected to the network must be powered and grounded for the infotainment system to work. If, for any reason, a control module is unable to handle (receive or transmit) signals onwards on the MOST network, or if there is an open-circuit in the fiber optic cable, the infotainment control module (ICM) will shut down all functionality.
Communication on the fiber optic net is one-directional. The control modules on the MOST network receive light signals, amplify them and then send them onwards. The MOST connectors for the control modules contain two fiber optic cables, one for incoming and one for outgoing signals.
If the fault is intermittent, it has been registered previously but is no longer present. Intermittent faults can either be caused by interference when starting the MOST network, or by intermittent faults in the power supply/ground for one of the control modules in the network. The fault is evaluated depending on how it occurs. If the fault recurs, fault-trace for permanent faults.
It can be difficult to diagnose intermittent faults using a ring break diagnostic because for this to work the fault must occur during the diagnostic.
If the fault is permanent, perform a ring break diagnostic to locate the open-circuit.
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