Function

Function

Alarm
See Design and Function, Alarm.

Central locking
See Design and Function, Central locking.

Battery voltage
The task of the rear electronic module (REM) is to check the voltage of the battery. The value of the voltage is transmitted out on the CAN network as a reference for other control modules.
The Central electronic module (CEM) receives this signal and checks it against its own supply voltage from the battery. The value is used when diagnosing the charging function.

Fuel level (Bi-fuel)




The fuel level in the gasoline tank is measured by the fuel level sensor (7/143). The level in the gas tank is measured by the fuel level sensor (7/156) (CNG) or (7/153) (LPG). The signals from the sensors are transmitted to the rear electronic module (REM) (4/58).
The rear electronic module (REM) calculates the quantity of fuel remaining in each tank and transmits this information via the controller area network (CAN) to the driver information module (5/1) and engine control module (ECM) (4/46). The driver information module (DIM) also receives data via the controller area network (CAN) from the engine control module (ECM) (4/46) indicating which type of fuel the car is running on. The gas level in the tank is displayed via the fuel gauge. The gasoline fuel level is displayed in the text window in the driver information module (DIM).

Shut-off valve (Bi-fuel)




The rear electronic module (REM) (4/58) controls the shut-off valves, (8/88-90) (CNG) and (8/76) (LPG), via a relay (which supplies the valves with power when they should be open.
The rear electronic module (REM) receives information via the controller area network (CAN) from the engine control module (ECM) (4/46) indicating that the car should run on LPG or CNG. The rear electronic module (REM) also receives information via the controller area network (CAN) from the central electronic module (CEM) (4/56) indicating the position of the ignition and data about collision status. When the ignition is on and no collision has been registered, the rear electronic module (REM) activates the relay, which supplies the valves with power.
The rear electronic module (REM) deactivates the relay in the following cases:
- there is a signal from the engine control module (ECM) indicating that gasoline operation has been selected
- ignition off
- the collision status changes
- there is a fault in the communication on the controller area network (CAN).
The relay can be activated via a diagnostic command, for example, to allow the tank to be drained. Activation is carried out in VIDA via the vehicle communication socket.

Diesel filter preheating (Diesel)




The rear electronic module (REM) (4/58) controls warming up the diesel filter.
The rear electronic module (REM) checks that the conditions to start the diesel filter have been met. The following is transmitted on the controller area network (CAN):
- the engine control module (ECM) (4/46 sends a signal indicating that the engine is running
- the central electronic module (CEM) (4/56) transmits a signal indicating the position of the ignition key. The key must be in position II.
When the conditions are met, the rear electronic module (REM) grounds the output to a relay. There is a temperature switch (8/85) on the relay circuit. This is closed at approximately -3 °C which activates the relay. The temperature switch switches off at approximately 5 °C which breaks the power supply by releasing the relay. The diesel filter is then powered via the relay.

Rear fog lamp




The rear fog lamps (10/46, 10/53) are activated by pressing the button for the rear fog lamps in the lamp switch module (3/111). The light switch module (LSM) transmits a request to light the lamps to the central electronic module (CEM) (4/56) using serial communication. The central electronic module (CEM) transmits the request to the rear electronic module (REM) (4/58) via the Controller area network (CAN).
Central Electronic Module (CEM) transmits information:
- back to the light switch module (LSM) to light the LED in the button
- via the Controller area network (CAN) to the driver information module (DIM) (5/1) to light the indicator lamp for the rear fog lamps.
The rear electronic module (REM) sends the status of the lamp fault via the Control area network (CAN) to the central electronic module (CEM). In the event of a fault, the central electronic module (CEM) transmits data via the Control area network (CAN) to the driver information module (DIM) which displays a text message.

Rear parking lamps/license plate lighting




The parking lamps (10/17-18) and license plate lighting (10/3) light when:
- the knob in the light switch module (LSM) (3/111) is in the low beam position
- the knob in the light switch module (LSM) is in the parking lamp position
- low beam is lit via the low beam automatic function.
The lamp switch module (LSM) transmits data using serial communication to the central electronic module (CEM) (4/56) to activate the lamps.
The central electronic module (CEM) transmits the data via the controller area network (CAN) to the rear electronic module (REM) which activates the lamps.
The rear parking lamps and license plate lighting are powered via the rear electronic module (REM) (4/58).
In the event of a bulb fault for the rear parking lamps or license plate lighting, data is transmitted on the controller area network (CAN) from the rear electronic module (REM) to the driver information module (DIM) (5/1) and a text message is displayed.
There is a Limp Home function for the parking lamps so that they will work even if there is a fault in the controller area network (CAN) or in the serial communication between the light switch module (LSM) and the central electronic module (CEM).

Back-up lamp





Manual transmissions
The back-up (reversing) lamps (10/48, 10/55) are activated when back-up (reverse) gear is selected. The switch (3/10) on the transmission is then closed. A directly connected signal is transmitted to the central electronic module (CEM) (4/56) indicating that back-up (reverse) gear is selected. The central electronic module (CEM) transmits the information via the controller area network (CAN) to the rear electronic module (REM) (4/58) to activate the back-up lamps. The rear electronic module (REM) activates the relay and the back-up lamps are supplied with power via the relay.

Automatic transmission
The back-up (reversing) lamps (10/48, 10/55) are activated when back-up (reverse) gear is selected. The transmission control module (TCM) (4/28) transmits information via the Control area network (CAN) to the central electronic module (CEM) (4/56) indicating that back-up (reverse) gear is selected. The central electronic module (CEM) transmits the information via the controller area network (CAN) to the rear electronic module (REM) (4/58) to activate the back-up lamps. The rear electronic module (REM) activates the relay and the back-up lamps are supplied with power via the relay.

Brake light




The stop lamps (10/43, 10/50) are activated when the brake switch is (3/9) closed. A directly connected signal is transmitted via the central electronic module (CEM) (4/56) to the rear electronic module (REM) (4/58) and activates the relay. The lamps are powered via the relay. The central electronic module (CEM) transmits the data via the Controller area network (CAN) to the rear electronic module (REM) indicating that the stop lamp switch is activated. The rear electronic module (REM) sends status information for the lamp fault via the Control area network (CAN) to the central electronic module (CEM). In the event of a fault, the central electronic module (CEM) transmits data via the Control area network (CAN) to the driver information module (DIM) (5/1) which displays a text message.

High level stop lamp




When the stop lamp switch (3/9) is closed, a signal is transmitted to the central electronic module (CEM) (4/56). The signal is transmitted from the central electronic module (CEM) to the rear electronic module (REM) (4/58) via a directly connected cable. The high mounted stop lamp is supplied with power directly from the rear electronic module (REM). The stop lamp is supplied with power for as long as the stop lamp switch is closed.

Rear windshield wiper/washers (V70/XC70/XC90)
See Design and Function, central electronic module (CEM).

Rear demist




Rear demist (9/2) is activated by pressing the switch on the climate control module (CCM) (3/112). The climate control module (CCM) transmits the data via the Control area network (CAN) to the central electronic module (CEM) (4/56). The central electronic module (CEM) checks that the conditions to start the demist have been met. If the conditions are met, a request is transmitted via the controller area network (CAN) to the rear electronic module (REM) (4/58) to activate the relay. The rear electronic module (REM) powers the relay and the demister is powered.
The central electronic module (CEM) also transmits a request via the Control area network (CAN) back to the climate control module (CCM) to light the LED in the switch.

Electric folding rear head restraints (S60/S80)




The rear head restraints fold down when the switch on the climate control module (CCM) (3/112) is pressed. The climate control module (CCM) transmits a request via the Controller area network (CAN) to the rear electronic module (REM) (4/58) to activate the function. The rear electronic module (REM) activates the relay. The solenoids (8/59-60) in the head restraints are then powered by the relay.

Cargo compartment lighting (S60/S80/XC90)




The cargo compartment lighting is activated when the trunk lid is opened. The central electronic module (CEM) (4/56) receives a signal from the lock (3/78) in the trunk lid. The central electronic module (CEM) transmits the information via the Controller area network (CAN) to the rear electronic module (REM) (4/58) about the status of the trunk lid. A request for cargo compartment lighting is also sent from the upper electronic module (UEM) (4/70) to the rear electronic module (REM). The lamps (10/127-128 (S60/S80)) (10/173 (XC90)) are then powered directly from the rear electronic module (REM).
For the XC90, the roof lamp in the cargo compartment also lights. For further information about the inner roof lighting, see Design and Function, upper electronic module (UEM).

Rear 12V socket (V70/XC70/XC90)




When a power consuming component is connected to the rear 12V socket (17/19), the power consumption is measured via a shunt inside the rear electronic module (REM) (4/58). The rear electronic module (REM) transmits status data via the controller area network (CAN) to the driver information module (DIM) (5/1) which displays a text message.
The text message is also displayed if a power consuming component is connected when changing from ignition position:
- II to I
- I to 0 and
- 0 to the key is removed.
There is also an audible warning note when the key is removed.

Parking assistance system (optional extra)




The parking assistance system warns the drivers of close objects when reversing.
The driver is warned by a sound signal from the loudspeakers for the audio module (AUM) (16/1). On the XC90, the signal is transmitted via the infotainment control module (ICM) (16/94).
The rear sensors (7/131, 7/132, 7/133 and 7/134) are active when the ignition is on in position II and back-up gear (R) is selected. The sensors are deactivated automatically when the gear selector lever is moved from R to any other position. The sensors detect objects at a distance of 1.5 meters. A beeping sound is heard from one of the rear loudspeakers. If the vehicle is left-hand drive, the sound comes from the rear right-hand loudspeaker (16/5). If the vehicle is right-hand drive, the sound comes from the rear left-hand loudspeaker (16/6). The sound signal becomes more frequent as the distance to the object reduces. The sound is constant at distances below approximately 30 cm.
The front sensors (7/204, 7/205, 7/206 and 7/207) (option) are active when the ignition is on in position II and gear R is selected, or when the ignition is on in position II and the car is driven forwards at speeds below 10 km/h. The sensors are automatically deactivated when the car is driven forwards at above 15 km/h. On cars with automatic transmissions, the sensors are deactivated if P is selected, irrespective of speed. The sensors detect objects at a distance of 0.8 meters. A beeping sound is heard from one of the front loudspeaker on the driver's side (16/4). The sound signal becomes more frequent as the distance to the object reduces. The sound is constant at distances below approximately 30 cm.
A signal is transmitted from the parking assistance module (PAM) (4/86) to the rear electronic module (REM) (4/58). This indicates whether the buzzer should be switched on or off.
The rear electronic module (REM) then transmits a signal to the audio module (AUM) on the controller area network (CAN). On the XC90 this signal is sent to the Infotainment Control Module (ICM).
If a trailer or caravan is connected, the parking assistance system must be deactivated. This is done using the switch on the climate control module (CCM) (3/112).
The climate control module (CCM) then transmits a signal to the rear electronic module (REM) via the controller area network (CAN). The parking assistance system is deactivated.

Tow hitch (optional extra)




The trailer module (TRM) (4/110) ensures that the correct type of signals are transmitted to the tow hitch cable harness.
The rear electronic module (REM) (4/58) receives messages on the controller area network (CAN) from the central electronic module (CEM) (4/56) about when output signals to the turn signal lamps, parking lamps, back-up lamps and fog lamps should be activated. The rear electronic module (REM) then transmits a direct signal to the trailer module (TRM).
The trailer module (TRM) forwards the signal to the tow hitch cable harness.
The +12 V output signal is activated when the ignition key is turned from position 0 to I, II or III. The rear electronic module (REM) transmits the signal.
+12 V supply is direct from the battery.
The rear electronic module (REM) transmits messages on the controller area network (CAN) to the central electronic module (CEM) and driver information module (DIM) (5/1), if a trailer is connected to the tow hitch connector socket. A separate indicator lamp in the driver information module (DIM) indicates when the turn signal lamps are used and the trailer is connected. If one of the turn signal lamp bulbs is defective the separate indicator lamp will not light.
The output signals for back-up lamps, fog lamps and +12 V in the socket for the tow hitch connector are market dependent. The socket for the tow hitch connector is available in a number of variants with different numbers of pins.

Rear window lift mechanisms




The rear window lift mechanisms are operated using switches (3/85-86) in the door panels.
When the window lift mechanisms are operated from the driver's position, data is transmitted from the driver's door module (3/126) via the controller area network (CAN) to the rear electronic module (REM) (4/58) which transmits a signal to the correct relay.
There is a switch in the driver's door module (DDM) to allow for child locking, where the windows can only be operated from the driver's position. When the function is active, information is transmitted via the controller area network (CAN) to the rear electronic module (REM) to disconnect the relay. The circuit for the rear switch is then broken.
When the child lock is activated, the lighting in the rear switches goes out.