Part 2
Design (Continued)
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).
Speed-dependent power steering (option)
The unit for speed-dependent power steering is located under the instrument panel over the glove box. The unit receives a control signal from Central electronic module (CEM), which informs how much current that the unit for speed-dependent power steering should deliver to valve speed-dependent power steering on the steering gear.
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
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.
Panorama roof (only XC60)
Vehicles equipped with panorama roof are equipped with two sun roof modules (SRM) (4/33). The panorama roof is operated using the same switches as the roof hatch.
The switches are located in the same module as the front reading lamps.
The front sun roof module (SRM) is located in front of the glass roof and operates the glass hatch. The rear sun roof module (SRM) is located behind the glass roof and operates the headlining. The position of the panorama roof is determined by four hall sensors, two in each control module.
Both motors are directly connected to the switch and to the central electronic module (CEM). Some signals that are intended for the rear motor are sent via the front motor, which in turn forwards the signals via LIN communication to the rear motor.
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 located below the cowl. From structure week 200946 the siren is fitted in the left-hand wheel housing, above/behind the wheel. After replacing the siren, it must be configured, which is carried out 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 sound wave has a different phase compared to the transmitted sound wave. 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.
Clutch pedal switch (manual transmissions only)
The clutch pedal switch is directly connected to Engine control module (ECM). Central electronic module (CEM) receives information about the clutch pedal switch's status via a CAN-signal. The signal is used as part of the conditions in the Immobilizer.
For more information on the clutch pedal switch, see Design and Function - Engine control module (ECM).
For more information on the Immobilizer, see: Design and Function - Immobilizer/Start lockout.
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)
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).
Battery Monitoring Module
Note! The battery monitoring module is only available in vehicles with the brake energy regeneration function.
The battery monitoring module is fitted on the battery's negative terminal and its main function is to monitor battery status.
For further information. See Design and Function - Brake energy regeneration.
Secondary battery (model year 2011-, only on vehicles with the function automatic start/stop of engine).
The secondary battery is used in the function automatic start/stop of engine, see Design and Function, Automatic start/stop of engine.
The secondary battery is only connected to the vehicle's electrical system when the engine is restarted after autostop and when the secondary battery needs to be charged. Connecting the secondary battery to the vehicle's electrical system is controlled by Engine control module (ECM) via a relay.
Central electronic module (CEM) is monitors the secondary battery's voltage and controls the secondary battery's charging.
When the secondary battery needs charging the Central electronic module (CEM) sends a request to Engine control module (ECM) to connect the secondary battery to the vehicle's electrical system. When the alternator is charging and secondary battery is connected, the battery is charged.
Note! When restarting the engine, it is only Engine control module (ECM) that controls connection of the secondary battery.
When the engine is on (alternator charging) and the secondary battery is connected to the vehicle's electrical system, the secondary battery's voltage will be the same as the rest of the electrical system's voltage. If the secondary battery is disconnected, the voltage will be lower.
Note! During key start for vehicles with automatic transmission and the start/stop, the start sequence is the same as at autostart. For more information, see "Automatic start/stop of engine - Description" VCC-421709. If the secondary battery is discharged or in the event of certain component faults, the start only occurs by means of the main battery which then supplies the entire electrical system and starter motor.
See also Design and Function - Automatic start/stop of engine.
The secondary battery's voltage can be diagnosed.
Blind spot Information System (BLIS) (only S60 (11-)/V60)
The blind spot information system (BLIS) is an auxiliary system designed to help the vehicle's driver when moving sideways. The blind spot information system (BLIS) consists of two cameras integrated in the external rear view mirrors and two LEDs located in the panel at the front of the inside of the respective windows.
The central electronic module (CEM) communicates with the left camera module (LCM) and the right camera module (RCM) via LIN-communication.
Note! Vehicles with Blind spot Information System (BLIS) that are not equipped with function for keyless vehicle will still be equipped with Keyless vehicle module (KVM), only the module but not the function. Keyless vehicle module (KVM) is needed to make a communication bus available on Central electronic module (CEM) which normally is used for communication with remote receiver module (RRX). Instead these vehicles are equipped with remote receiver (TRX) connected to Keyless vehicle module (KVM).
The blind spot information system (BLIS) is always activated automatically at speeds over 10 km/h (6 mph). The blind spot information system (BLIS) can be deactivated and reactivated using the switches on the comfort panel of the climate control module (CCM). A signal is then sent via Central electronic module (CEM) to the left camera module (LCM) and right camera module (RCM) with a request to deactivate or reactivate the blind spot information system (BLIS).
When reverse gear is engaged, the blind spot information system (BLIS) is deactivated.
The system reacts to vehicles in the blind spot if:
- the vehicle is traveling past another vehicle with a speed difference of up to 10 km/h.
- another vehicle passes with a speed difference of up to 70 km/h.
Blind spot Information System (BLIS) can be diagnosed in the Central electronic module (CEM).