Compass
The compass detects the magnetic pull of the North and South Poles. Using this, the compass calculates the direction in which the front of the vehicle is pointing.
The display in the top right-hand corner of the rear view mirror shows the compass direction. Eight different directions can be displayed.
- North
- North East
- East
- South East
- South
- South West
- West
- North West
The primary task of the upper electronic module (UEM) is to manage the functions of the
- Siren control module (SCM)
- Sun roof
- Mass movement sensor module (MMS)
- Rain sensor module (RSM)
- Interior roof lighting
- Sun visor lighting
- Remote control
- Automatic rear view mirror anti-dazzle
- Seat belt reminder
- Tire pressure warning
- Indication of disconnected passenger airbag (PAD- Passenger Airbag Deactivated)
- Compass
The control module is integrated in the rear view mirror. If the control module is replaced, the rear view mirror assembly must also be replaced.
The upper electronic module (UEM) communicates with directly connected components and with other control modules and components via serial communication and the 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 an error. In certain cases the upper electronic module (UEM) replaces the faulty signal with a substitute value.
Any diagnostic trouble codes (DTCs) are stored in the control module memory. The data can be read off using VIDA.
A simple way to check that the upper electronic module (UEM) is supplied with power is to activate the seat belt reminder function. Activate the seat belt reminder by sitting in the driver's seat. Switch on the ignition, do not fasten the seat belt. If the seat belt reminder lights, the upper electronic module (UEM) is supplied with voltage. Another way of checking that the control module is supplied with voltage is to switch on one of the rear reading lamps.
For further information, also see Signals .
The table below summarizes the input signals to and output signals from the upper electronic module (UEM). The signal types are divided into directly connected signals, serial communication and controller area network (CAN) communication. The illustration below displays the same information with the Volvo component designations.
| Input signals | Output signals |
|---|---|
| Directly connected | Directly connected: (power supply unless otherwise stated) |
| Control signal reading lamps (x 4) Remote control (data) Remote control (frequency) Remote control (signal strength) Photo sensor rear view mirror (x 2). | Mass movement sensor module (MMS) (optional extra) Reading lamps (x 4) Roof lighting Cargo compartment lighting Voltage supply signal EXT. X Remote control receiver Anti-dazzle in the rear view mirror (optional extra) Diodes in the rear view mirror. |
| Via serial communication | Via serial communication |
| Siren control module (SCM) (16/35) (optional extra) Sun roof module (SRM) (4/33) (optional extra) Mass movement sensor module (MMS) (7/122) (optional extra) Rain sensor module (RSM) (7/149) (optional extra). | Siren control module (SCM) (16/35) (optional extra) Sun roof module (SRM) (4/33) (optional extra) Mass movement sensor module (MMS) (7/122) (optional extra) Rain sensor module (RSM) (7/149) (optional extra). |
| Via Controller Area Network (CAN) communication | Via Controller Area Network (CAN) communication |
| Central electronic module (CEM) (4/56) Driver door module (DDM) (3/126) Engine control module (ECM) (4/46) Phone module (PHM) (16/60) (optional equipment). Supplemental restraint system module (SRS) (4/9). | Accessory electronic module (AEM) (4/78) (optional equipment) Central electronic module (CEM) (4/56) Driver door module (DDM) (3/126) Passenger door module (PDM) (3/127) Phone module (PHM) (16/60) (optional equipment). Rear electronic module (REM) (4/58). |