Reading Off The Position Of The Open-Circuit

Fig 1: Identifying Ignition ON

Courtesy of VOLVO CARS CORPORATION

Ignition on.
Reading off the result from a ring break diagnostic

Click the VCT2000 symbol to read off the result of the ring break diagnostic.

As well as the result from the ring break diagnostic, a list of the control modules included in the MOST network is provided for that car.

The following result can be obtained from a ring break diagnostic:

If the fault occurs when the ring break diagnostic is run, the result will be presented as an open-circuit position.

If the fault does not occur when the ring break diagnostic is run, the result will be OK. If this is the case, select alternative 3 below.
- If the diagnostic indicates an open-circuit in the communication on the MOST network, the result will be an open-circuit position
- The result will be OK if there is no fault on the MOST network
- If the infotainment control module (ICM) receives a signal on the MOST network but is unable to decode it because the luminance is weak or the signals are distorted, the result will be POOR.
Determining the position of the open-circuit

The position of the open-circuit is calculated by working backwards in the MOST network from the infotainment control module (ICM).

NOTE:
The ring break diagnostic only counts backwards, irrespective of which, or how many control modules, are installed in the car. To determine the position of the open-circuit, check the list to, see which control modules are installed in that particular car. Then count backwards following the determined order. The number of control modules can vary between 3-8.

Two examples are outlined below:
- The first open-circuit position corresponds to 0. This means that the open-circuit is in the antenna module (ATM) or in the cable between the antenna module (ATM) and the infotainment control module (ICM)
- If the position is 1, go one step backwards in the chain. The open-circuit is in the subwoofer module (SUB) or in the cable between the subwoofer module (SUB) and the antenna module (ATM). The open-circuit can also be caused by the optical connector in the antenna module (ATM) being damaged so that the antenna module (ATM) is not able to interpret the incoming signal from the subwoofer module (SUB) correctly.
  NOTE:
  The subwoofer module (SUB) is not standard. If one is not installed, the open-circuit position 1 applies to the audio module (AUD).
Select the alternative for the control module to be checked.

Alternative 1:

Antenna module (ATM)

Subwoofer module (SUB)

Audio module (AUD)

CD player module (MP2)

Alternative 2:

Phone module (PHM)

MD player module (MP1)

Multimedia module (MMM)

Infotainment control module (ICM)

Alternative 3:

The result from the ring break diagnostic indicates that the MOST network is OK.

The result from the ring break diagnostic is POOR.

Other information:
- For information about location and order of control modules in the MOST network, see LOCATION OF COMPONENTS
Fig 2: Identifying VCT2000 Diagnostic Tool Symbol In VIDA
Courtesy of VOLVO CARS CORPORATION

Fig 3: MOST Bus (Media Oriented System Transportation) Communication Diagram
Courtesy of VOLVO CARS CORPORATION

Select an alternative.