AUDIO MODULE (AUD) Volvo XC90 I facelift

AUDIO MODULE (AUD)

The primary task of the audio module (AUD) is to manage the functions for

1. the front, center and rear loudspeakers
2. the subwoofer module (SUB)
3. the headset, headset panel
4. the microphone.

The audio module (AUD) communicates with directly connected components and with other control modules and components via the MOST network, a fiber optic network used for communication.

The audio module (AUD) checks executed activations and input/output signals via its integrated diagnostics. If the control module detects a fault, a diagnostic trouble code is generated. Any diagnostic trouble codes are stored in the control module memory. The information can be read with the help of VIDA via the data link connector in the car.

In order to work correctly on the MOST network, the infotainment control module (ICM) checks that the serial number in the audio module (AUD) is correct. The audio module (AUD) will not function if the number is incorrect. Try switching the ignition off and on if there are problems when replacing the control module.

A simple way to check whether the control module is functioning is to switch on the radio and to then change the volume. The volume from the loudspeakers should rise and fall with the changes.

The Audio module (AUD) is a slave module on the MOST network. The infotainment control module (ICM) is the master control module.

There are three versions of the audio module (AUD)

1. Performance
2. High Performance
3. Premium Sound.

The number of functions and loudspeaker outlets varies between the versions. The power output of the versions is also different.

The control module is under the right-hand front seat.

The table below summarizes the input signals to and output signals from the audio module (AUD). The signal types are divided into directly connected signals and MOST communication. The illustration below displays the same information with the Volvo component designations.

Scheme 122

Scheme 123

The audio module is an amplifier which is connected to the MOST network. It has the following functions

1. to carry the sound signal transmitted on the MOST network out to the directly connected loudspeakers and to the headsets as analogue signals
2. to carry voice messages from the microphone, out on the MOST network.
3. to transmit requests from the headset panel to change to the next or the previous track or to change the sound source.

If there is a subwoofer module installed on the MOST network, the audio module can process the incoming signal and transmit it to the subwoofer module.

The following versions of Audio module are available

1. Headset panel
2. Headset panel

Audio module and have 4x40 W output and has 5x130 W.

Each version of the audio module (AUD) has a different number of loudspeakers and different loudspeaker models.

The audio module (AUD) can run a number of different functions, but these functions can also be activated by other nodes. An example of these functions is lowering and increasing the volume. The signal comes from the infotainment control module (ICM), but it is the audio module (AUD) that actually changes the volume. The functions are described below.

1. Adjustable volume , raises and lowers the volume
2. Adjustable bass , raises and lowers the bass level
3. Adjustable treble , raises and lowers the treble level
4. System generated sound signals , assist other nodes in the system with single sound signals generated in the control module, for example alarm signals for the park assistance function.
5. Limiter , the limiter function in the control module does not permit an increase in the power output level if this leads to a fall in sound quality
6. Mixing , mixing allows numerous different sound types to be mixed. In this case, the different sound types are foreground noise, background noise and system generated sound signals. An example of this is where a CD is playing (background noise) and the carphone rings. The ringing signal will be heard through the loudspeakers while the volume of the music drops at the same time
7. Digital bass loudspeaker output, via MOST network, transmits signals to Subwoofer module. No foreground noise must be included in the signals.
8. Bass compensation , the bass from the control module is compensated or modified depending on the volume level and the speed of the car. If the vehicle speed and volume level changes, the bass compensation is also changed
9. Treble compensation , the treble in the control module is compensated or modified depending on how the volume is changed. If the volume changes, the treble compensation also changes
10. Equalizer setting, sound compensation , there are different settings for the sound from the audio module. This compensates for factors such as the location of the loudspeakers and the layout of the car interior.
11. a surround decoder for playing sound.

There are two types of sound, foreground sound and background sound. The sounds which are foreground and background are listed below.

Foreground sound

1. navigation
2. system generated sound from the audio module
3. traffic messages.

Background sound

1. analogue radio, AM/FM
2. CD player
3. playing sound via the AUX input.

The functions in the different versions of the audio module are

1. adjustable volume
2. adjustable bass level
3. adjustable treble level
4. system generated sound signals
5. limiter
6. mixing
7. digital bass speaker output
8. bass compensation
9. treble compensation
10. equalizer

1. adjustable volume
2. adjustable bass level
3. adjustable treble level
4. system generated sound signals
5. limiter
6. mixing
7. digital bass speaker output
8. bass compensation
9. treble compensation
10. equalizer
11. DPL2 - Dolby ProLogic II.

Scheme 124

and

For High Performance and High Performance HP, 8 loudspeakers are used. It is a 2 way loudspeaker system with base/mid-range speakers and separate trebles. The speakers are installed in the front and rear doors. There are also 2 speakers installed in the D-posts.

The impedance is 2 ohms for the base/mid-range loudspeakers and 8 ohms for the treble speakers.

For Premium Sound, 9 loudspeakers are used. It is a 2 way loudspeaker system with base/mid-range and separate trebles. The speakers are installed in the front and rear doors. There are also 2 loudspeakers installed in the D-posts. To increase the sound there is a 2 way central loudspeaker in the dashboard.

The impedance is 4 ohms for the base/mid-range loudspeakers and 8 ohms for the trebles. The center loudspeaker impedance is 6 ohms if a display screen is installed in the dashboard, otherwise the central loudspeaker impedance is 8 ohms.

Scheme 125

The Audio module (AUD) has outputs for connections to the left and right headset panel. The headset panels are located on the inside of the C-post. Each headset panel has a control for volume, next track, previous track and source.

Scheme 126

The microphone is directly connected to the audio module (AUD). The microphone transmits analog signals to the control module.

Telephone calls can be made either hands free or using the handset. During handsfree calls, the microphone and speaker are used which are connected to the audio module (AUD). The microphone is phantom fed via the audio module (AUD).

This function is used to read the status or value of parameters. The status or value can be presented digitally.

The control module is located under the right front seat.

After replacement of the audio module (AUD), the infotainment control module (ICM) checks its unique serial number. If the serial number is incorrect, the audio module (AUD) will not work. If the problem remains after software download, try switching the ignition off/on.

Select the MOST network for a total download of software to the vehicle.

Scheme 127

All functions in the audio module (AUD) (16/105) are controlled by the signals from other nodes in the MOST network.

To initiate audio playback, a control module transmits a request to the infotainment module (ICM) (16/94). The infotainment control module (ICM) allocates the request to the audio module (AUD) then the control module can transmit data via the MOST network to the audio module (AUD).

The infotainment control module (ICM) processes changes to the volume, balance, bass, treble and equalizer settings. The infotainment control module (ICM) transmits the changes via the MOST network to the audio module (AUD) which then carries out the changes.

The control modules on the MOST network which use the audio module (AUD) to play back sound are

1. multimedia module (MMM) (16/108) for voice guiding (navigation)
2. integrated audio module (IAM) (16/1)
3. Subwoofer module (SUB) (16/79)
4. phone module (PHM) (16/60), handsfree speaker sound.

The audio module (AUD) can generate simple sound signals which are used for example to warn the driver and passengers if there are problems. These signals are transmitted from the infotainment control module (ICM) via the MOST network to the audio module (AUD).

When the Audio module (AUD) has received optical signals on the MOST network, the signals are transmitted onwards as analog signals to

1. loudspeaker left front (16/4, 16/55)
2. loudspeaker right front (16/3, 16/56)
3. Loudspeaker left rear (16/6)
4. Loudspeaker right rear (16/5)
5. loudspeaker left D-post (16/57)
6. loudspeaker right D-post (16/58)
7. Center loudspeaker (16/26) (option).
8. headset panel, left, rear (16/111)
9. headset panel, right, rear (16/112).

The microphone (16/77) is directly connected to the audio module (AUD). The microphone transmits analog signals to the control module.

When sound compensation is required, the infotainment control module (ICM) transmits sound compensation signals via the MOST network to the audio module (AUD).