System Overview

Accessory Electronic Module (AEM)

System overview

Control module





The function of the accessory electronic module (AEM) is to allow certain accessories to exchange information with the controller area network (CAN) of the vehicle. The control module functions as an interface between accessories, which are not prepared for Controller area network (CAN) communication, and the Control area network (CAN) of the vehicle and its functions. This exchange of information means that accessories can be installed with greater functionality and higher quality.
The accessory electronic module (AEM) manages the following functions:
- relay for the electrical engine block heater
- outputs for external after-market alarms
- tele-mute for non-integrated carphones.

The functions managed by the accessory electronic module (AEM) may vary between different car models.

The accessory electronic module (AEM) is an accessory and is only available for order and installation as an after market item.

Adapter wiring is required when installing accessory electronic module (AEM). The control module is installed in the cargo compartment of the vehicles behind the side panel at the right-hand wheel arch.
After installation the accessory electronic module (AEM) is configured using software. Configuration is carried out via VIDA.

The control module communicates with directly connected components, and via a Controller area network (CAN).

The control module checks activations and input and output signals via an integrated diagnostic system. A diagnostic trouble code (DTC) is stored if the control module detects a fault. Any diagnostic trouble codes (DTCs) and stored in the control module memory and information can be read out using VIDA.

Signals
The table below summarizes the input signals to and output signals from the accessory electronic module (AEM) (4/78).
The signal types are divided into directly connected signals and Controller area network (CAN) communication. The illustration below displays the same information with the Volvo component designations.

NOTE: The signals are only available for installed accessories.





Input signals Output signals
Directly connected: Directly connected:
- The telemute signal from after - Start for the parking heater consisting of
market hands free unit to the +12 V to the relay for the electrical
carphone to mute the volume parking heater
- External alarm unit (status signals). on the sound system.

Via Controller Area Network (CAN) Via Controller Area Network
communication:Central electronic (CAN) communication:Infotainment
module (CEM) (4/56): control module (ICM) (16/1):
- Start and stop signal, to control - Telemute signal via infotainment control
the relay for the electrical module (ICM) via the MOST network to the
parking heater audio module (AUD).
- Alarm status, door status, key
status. Used by the accessory
electronic module (AEM) to
control the external alarm.

Steering wheel module (SWM) (3/254): Central electronic module (CEM) (4/56):
- Manual start and stop signal, - Start and stop signal, to control the
to control the relay for the relay for the electrical parking heater
electrical parking heater. Via
central electronic module (CEM).
- Start and stop signal, to control the combustion preheater module (CPM) (for fuel driven parking heaters).

Design

Timer start of the electrical parking heater





A timer control function can be connected to the electrical parking heater which is controlled via the accessory electronic module (AEM). The system consists of:
- a relay for the electrical parking heater
- cable harness between the relay and the accessory electronic module (AEM).

The relay is mounted on the engine block heater and controls the electrical parking heater and relay passenger compartment socket.

The relay acts as a switch and is supplied with power and controlled via the wiring from the accessory electronic module (AEM).
The relay is connected to the ground terminal in the engine compartment.

When post-installing the timer start system for the electrical parking heater the vehicle must be configured using new software which is carried out via VIDA.

There are diagnostics for the relay/control signal.

Alarm signal outputs
An after market alarm unit can be connected to the accessory electronic module (AEM). The system consists of four output signals which can be used as input signals in the external alarm system via a cable harness. The accessory electronic module (AEM) uses the existing Controller area network (CAN) to receive/forward signals for the vehicle alarm, key and door status.

When installing an after market alarm system the vehicle must be configured using new software. Configuration is carried out via VIDA.

There are diagnostics for the alarm signal outputs.

Tele-mute function for non-integrated mobile phones
The telemute function mutes the sound system when the mobile telephone rings.
The design consists of a signal input and a signal output. The input signal is digital (0 V/12 V) and the output signal is a Controller area network (CAN) communication.

When post-installing the hands free unit the vehicle must be configured using new software. Configuration is carried out via VIDA.
There are diagnostics for the tele-mute function.

Function

Starting the parking heater via the timer





The left-hand control stalk controls the start timer for the parking heater (3/133). No other timer is required when setting the timer control. The control stalk is directly connected to the steering wheel module (SWM) (3/254) which transmits a signal via the Controller area network (CAN) to the central electronic module (CEM) (4/56), which in turn transmits the signal on to the accessory electronic module (AEM) (4/78) when the electrical heater is to start.

The start timer functions on either the electrical or fuel driven parking heater. The accessory electronic module (AEM) is not involved when the fuel driven parking heater is selected. The heater to be used is selected in the driver information module (DIM) (5/1).

Alarm signal outputs





Output signals from the accessory electronic module (AEM) (4/78) are used when installing an after market alarm unit. Access is available to signals indicating:
- alarm status
- door status
- key status.

In this case the accessory electronic module (AEM) functions as a port between the Controller area network (CAN) of the vehicle and the after market alarm unit.

Tele-mute function for mobile telephones





In the event of a call the accessory electronic module (AEM) (4/78) receives an input signal from the hands free unit (post installed) and forwards this on the Controller area network (CAN) to the infotainment control module (ICM) (16/1). The infotainment control module (ICM) transmits the signal in turn via the MOST network to the audio module (AUD) (16/105) which mutes the loudspeakers.

The tele-mute function is available as an accessory for the accessory electronic module (AEM).