Reading Off The Position Of The Open-Circuit

Ignition on.

Reading off the result from a ring break diagnostic

Click the VCT2000 symbol in VIDA (Volvo scan tool) to read off the result of the ring break diagnostic.

The following results can be obtained from a ring break diagnosis:

NOTE:

For vehicle with structure week 200746 and later, Integrated Audio Module (IAM) is located second last in the MOST-loop, between Accessory USB unit (AUU) and Remote Digital Audio Receiver (RDAR). Structure week is presented in connection with reading out the result from ring break-diagnostics.

NOTE:

For vehicles with structure week 200835 and later, there are two market dependent alternatives of Remote Digital Audio Receiver (RDAR/DABM).

If the diagnostic detects a communication failure on the MOST network, the result will be the name of the control module positioned before the failure. The name of the control module, which has the relevant address, is also presented.
The result will be OK if there is no fault on the MOST network.
If the Infotainment control module (ICM) gets a signal on the MOST-net, but is unable to decode the signals due to the light intensity being too weak or the signals are too distorted, the result becomes poor signal .
If all control modules on the MOST network believe that they are slave nodes the result is diag all units slave .
If one or several control modules on the MOST-net consider themselves master nodes, the result becomes diagnosis multimaster .

NOTE:

If the result shows any of the three later alternatives, this must be verified by carrying out the entire test again. Then follow fault tracing for the relevant alternative.

Determining the position of the open-circuit

The Ringbreak diagnostic works so that after the control modules have been powered down and then restarted, each control module on the MOST-circuit sends its address to the Infotainment control module (ICM). This means that if the configuration is as illustrated in the top figure, the Remote Digital Audio Receiver (RDAR) will send first followed by the Multimedia module (MMM). The break is in the node before the one specified as the result in the diagnostic, alternatively in the cable between them All communication occurs clockwise in the loop illustrated.

An example is given below.

The result of the diagnostic is "AUU", which means Accessory USB unit (AUU). If the MOST-configuration is according to the upper figure, this means that the open circuit is in the Remote Digital Audio Receiver (RDAR) or in the line between Remote Digital Audio Receiver (RDAR) and Accessory USB unit (AUU). The open circuit may also be due to the optical contact in the Accessory USB unit (AUU) or in the Remote Digital Audio Receiver (RDAR) being damaged.

Select the relevant alternative.

Alternative 1

Infotainment Control Module (ICM).

Refer to CHECKING CABLES AND COMPONENTS, INFOTAINMENT CONTROL MODULE (ICM)

Alternative 2

Integrated audio module (IAM).

Multimedia module (MMM).

Bluetooth phone module (BPM).

Audio Control Module (AUD).

Accessory USB unit (AUU).

Phone module (PHM)

Remote Digital Audio Receiver (RDAR).