Part 2
Design (Continued)
Cargo compartment lighting
The cargo compartment contains two lamps for cargo compartment lighting. They are located on the right and left side of the cargo compartment, respectively. The lamps come on when the cargo compartment is open.
For the cargo compartment lighting to work, the relay for interior lighting must be activated.
Twilight sensor
The twilight sensor consists of a photo diode powered from the central electronic module (CEM). The conductivity of the diode depends on the amount of light to which it is exposed.
The diode is under a diffusing lens which reduces the sensitivity of the photo diode to the angle of the light hitting it. Increased light intensity reduces the voltage over the photo diode.
The control module measures the voltage across the photo diode and converts the voltage to information which is then transmitted to other control modules via the controller area network (CAN).
The twilight sensor is located in the same holder as the sun sensor and alarm diode.
There are diagnostics for the twilight sensor.
Sun sensor
The sun sensor consists of a photo diode powered from the central electronic module (CEM). The conductivity of the diode depends on the amount of light to which it is exposed.
The diode is located under a diffusing lens which reduces the sensitivity of the photo diode to the angle of the light hitting it. Increased sun intensity reduces the voltage over the photodiode.
The control module measures the voltage across the photo diode and converts the voltage to information which is then transmitted to the climate control module (CCM) via the controller area network (CAN).
The sun sensor and its housing are located in the center of the dashboard at the windshield together with the twilight sensor and alarm diode.
From and including structure week 200746, the sun sensor is replaced by twin sun sensors.
For further information, see Design and Function, climate control module (CCM).
There are diagnostics for the sun sensor.
Alarm LED
The alarm diode is an LED used to indicate alarm status. The diode sits in the same housing as the sun sensor and twilight sensor. The diode is directly connected to the central electronic module (CEM).
The diode flashes about once every three seconds when the alarm is armed. If the alarm has been triggered, the diode will flash rapidly the next time the vehicle is unlocked. It will continue flashing until the remote key is inserted in the start unit.
For further information, see Design and Function, Alarm.
There are diagnostics for the alarm diode.
Rear demist
There are heating loops in the glass for demisting and to prevent ice from forming. The loops heat up when they are supplied with power. The power supply is via a relay on the central electronic module (CEM).
Rear demist is controlled via a switch located on the climate control module (CCM) it can also be activated by selecting auto defrost rear, on the climate settings in the menu for the Infotainment control module (ICM).
Automatic rear demist starts when the engine starts and the outdoor temperature is below +9 °C.
In order to switch off the function before it is switched off automatically press in the switch again. Automatic switching off of the rear demist is dependent on the outdoor temperature according to:
- above +7 °C: activated for 12 minutes and then switched off.
- +7 °C to -15 °C: activated constantly for 20 min - it then switches to pulsing, 5 minutes activated and 1-10 min deactivated. The time it is deactivated is linearly dependent on the temperature.
- below -15 °C: activated for 20 minutes, then pulsing 5 minutes activated and 1 minute deactivated.
There are diagnostics for the relay and switch.
Fuel pump control module
The fuel pump is located in the fuel tank. The pump is regulated by the fuel pump control module. The central electronic module (CEM) controls a relay that supplies power to the fuel pump control module. The relay is directly connected on the central electronic module (CEM).
The central electronic module (CEM) communicates with the engine control module (ECM) via the CAN network in order to control the fuel pump. There is also a directly connected cable between the engine control module (ECM) and the fuel pump module. A pulsed signal for fuel pump control is transmitted on this cable.
For further information, see Design and Function, engine control module (ECM).
The central electronic module (CEM) also communicates with the supplemental restraint system (SRS) module via the controller area network (CAN). In the event of a collision, the supplemental restraint system module (SRS) transmits data and the central electronic module (CEM) shuts off the power supply to the fuel pump (FP).
For further information, see Design and Function, engine control module (ECM).
Fuel level (Gasoline/Diesel) /Fuel pump
The fuel level in the tank is measured with a sensor on the fuel pump. Vehicles with AWD have two sensors for fuel measurement - one on the fuel pump and one separate on the opposite side in the fuel tank. Vehicles without AWD have a sensor located on the fuel pump in the tank. The sensors are directly connected to the central electronic module (CEM).
There are different tables for different fuel tank sizes. The tables are stored in the central electronic module (CEM) and indicate which sensor values correspond to the remaining fuel in the tank. The central electronic module (CEM) determines which tank is in the car by reading a parameter.
The resistance of the sensor increases as the fuel volume in the tank decreases. The signals from the sensors are compared with the values in the fuel tank table to obtain a value for the remaining fuel volume. This data is displayed by the fuel gauge in the driver information module (DIM).
If the sensors are faulty, the fuel gauge will show 0.
The sensors are powered and grounded via the central electronic module (CEM).
There are diagnostics for the fuel level sensors.
For further information, see Design and Function, engine control module (ECM).
Power steering
The speed-dependent power steering unit sits under the dashboard above the glove compartment. The unit receives a control signal from the central electronic module indicating which permitted current the power steering pump may use during control.
One of the tasks of the central electronic module (CEM) is to limit the power consumption of a number of applications in certain modes. In some modes, the central electronic module (CEM) can reduce or stop the power consumption of the power steering.
For further information, see: Function Function
Electrical additional heater (certain markets)
Vehicles with diesel engines have an electrical additional heater (PTC element) on certain markets.
This comprises a heater element with ceramic resistors located in the heater housing. The air that flows into the passenger compartment is heated directly.
Rain sensor module (RSM)
The rain sensor (RSM) detects water on the windshield via optic measurement. An infrared light beam of known intensity illuminates part of the windshield. The intensity of the reflected beam is measured and compared with the transmitted intensity. If there is water on the surface of the windshield, the light beam is deflected a bit and will lose some of its intensity. If the beam is not reflected in its entirety, it is interpreted as water on the windshield and the windshield wipers are activated. On vehicles with rain sensor (RSM), the automatic function replaces the standard interval wipe function.
The rain sensor module (RSM) transmits signals to the central electronic module (CEM) using serial communication. The signals contain information about:
- how much rain is hitting the windshield
- a sudden splash on the windshield
- the outside light conditions.
The central electronic module (CEM) requests a certain windshield wiper speed based on this information.
The rain sensor module (RSM) is in front of the rear view mirror on the inside of the windshield. Cars with rain sensor modules (RSM) have a special windshield.
There are diagnostics for the rain sensor module (RSM).
Sun roof
Note! Vehicles with panoramic roof (option XC60) works in the same way as vehicles with roof opening panel.
The sun roof is operated using a switch in the same unit in the roof as for the front reading lamps. The sun roof can be opened and closed as well as angled up slightly at the rear edge.
The sun roof is driven by a motor which is in the roof, in front of the sun roof. The position of the sun roof is determined by two sensors.
The sunroof is equipped with a sunroof module (SRM).
There are diagnostics for the sun roof.
Siren
Information from the siren to the central electronic module (CEM) contains configuration and status data. This information is transmitted using serial communication.
When the alarm is armed, the siren continually sends status signals to the central electronic module (CEM).
The siren has a battery and a built-in battery charger so that it is independent of the power supply in the car. The battery charger maintains battery voltage in the built-in battery. When the alarm is armed, the power supply for the siren and the serial communication between the siren and the central electronic module (CEM) are monitored. The siren sounds if the car's power supply to the siren is cut off or if communication between the central electronic module (CEM) and the siren is interrupted. The battery and battery charger in the siren cannot be replaced separately. The entire siren must be replaced in the event of a fault.
The siren is below the plenum chamber. After siren replacement, the new siren must be configured using the diagnostic tool.
There are diagnostics for the siren.
For further information, see Design and Function, Alarm.
Movement sensor (IMS)
The movement sensor (IMS) uses ultrasound to detect movement inside the passenger compartment. The Doppler effect principle is used to determine if the received soundwave has a different phase compared to the transmitted soundwave. Any difference in phase is interpreted as movement in the vehicle. If a movement is detected, a trigger signal is sent to the central electronic module (CEM), which triggers the alarm.
The movement sensor (IMS) is located in the headlining in the center of the vehicle. This enables it to cover the greatest about of vehicle space possible.
Note! XC60 with panorama roof has a Mass Movement Sensor Module (MMS) in addition to the movement sensor (IMS), which uses microwaves to primarily check the front part of the vehicle. The Mass Movement Sensor Module (MMS) is located in the tunnel console under the cup holder.
There are diagnostics for both movement sensors.
For further information, see Design and Function, Alarm.
Horn
There are two horns in front of the radiator. There are four switches in the steering wheel. The horn is activated when one of these is closed.
The signal continues for as long as the switch is closed.
The horn is also activated when the panic alarm button on the remote key is pressed (certain markets).
The power supply to the horns is via a relay in the relay box in the engine compartment.
There are diagnostics for the relay for the horn.
Stop lamp switch
The brake light switch is located with the brake pedal. The switch is closed in its home position but opens when the brake pedal is depressed. The switch indicates that the brake pedal has been depressed and is used during brake light diagnostics and when deactivating cruise control.
Switch clutch pedal, internal (75%)
Switch clutch pedal, internal (75%) is located together with the clutch pedal.
The switch is open in resting position but is closed when the clutch pedal is pressed down to more than 75% of the whole stroke. When the switch is activated, a signal is sent to Central electronic module (CEM).
The signal is used as part of the conditions for the immobilizer.
For more information on the immobilizer, see Design and Function, Immobilizer/Start inhibitor.
Clutch pedal position sensor, external
Clutch pedal position sensor, external, is located together with the clutch pedal.
The sensor is only found on vehicles with manual transmission. The sensor is directly connected to Central electronic module (CEM) for voltage feed, ground, and signal. The sensor gives an analogue signal out to Central electronic module (CEM) which is proportional to how far the pedal is pressed down. The information is used in different ways depending on how the vehicle is equipped.
The signal is used as one of the conditions for the immobilizer and by the adaptive cruise control function.
For more information on the immobilizer, see Design and Function, Immobilizer/Start inhibitor.
Accelerator pedal (AP) position sensor
The accelerator pedal position sensor is located with the accelerator pedal. The sensor transmits a PWM signal to the engine control module (ECM) and an analog signal to the central electronic module (CEM). The signal is proportional to how far down the accelerator pedal is pressed. The sensor is powered and grounded via the central electronic module (CEM). The sensor has a separate ground for the PWM signal.
For further information, see Design and Function, engine control module (ECM).
Tire pressure monitoring system (TPMS)
Note! Vehicles with keyless lock system only have Remote Keyless Entry (RKE) and vehicles without keyless lock system only have Remote Receiver Module (RRX). For the market in Japan there is only Remote Keyless Entry (RKE) regardless of lock system.
The purpose of the tire pressure monitoring system, TPMS, is to enable the driver to have optimum tire pressure by giving a warning when the pressure in any of the tires becomes too low. Correct tire pressure is important for:
- achieving good fuel economy
- achieving optimum comfort and good driving characteristics
- preventing flat tires due to too low tire pressure.
The function is integrated in the central electronic module (CEM). Sensors are installed together with the air valve on each wheel to measure the air pressure in the tires.
Note! The system must be regarded as a driver aid to maintain the correct tire pressure. The system must NOT be regarded as a warning system that indicates that there is a serious problem with the vehicle. No tire is completely sealed - there is always slight leakage as the tire can never be completely sealed to the rim. When inflating the tire with air, you must, as much as possible, ensure that the tires are at same temperature as the outside temperature. Furthermore, "Comfort pressure" should not be applied as this gives a tire pressure that is too close to the parameter for the monitoring system, which means that even small changes in temperature or load can cause the pressure in the tires to be too low for the system to consider acceptable. When inflating with air, the tires must be filled to the pressure stated on the decal located on the car body. The pressure is calculated with regard to fuel economy, comfort and safety. Therefore, these pressures MUST be followed. If the decal is missing or damaged, a new one must be ordered and applied. This is especially important on vehicles with TPMS.
For more information, see Design and Function, Tire pressure monitoring system (TPMS).
Tire pressure sensor
The tire pressure sensors are installed together with the air valve on the rim. The sensor consists of a pressure sensor, a communication circuit, an acceleration sensor and a battery.
Note! Special procedures are required for removing the tire from the rim depending on vehicle model and tire type. This is to prevent damaging the sensor. See the specific mechanical information instruction under Repairing/Removal, replacement and installation.
For more information, see Design and Function, Tire pressure monitoring system (TPMS).