Design

Design

Alarm
See Design and Function, Alarm.

Central locking
See Design and Function, Central locking.

Immobilizer
See Design and Function, Immobilizer.

Headlamps




The headlamps at the front of the car are operated by the light switch module (LSM) which is positioned on the dashboard to the left of the steering wheel. The signals between the light switch module (LSM) and the central electronic module (CEM) are transmitted via serial communication. Low and high beam are operated by moving the left-hand control stalk towards the steering wheel.
The power supply for the lamps is via two directly connected relays on the central electronic module (CEM). One relay is for low beam and the other for high beam. The power supply for low beam is also via a shunt so that faults in the lamp can be detected.
For Bi-Xenon lamps the reflector in the lamp housing is moved by an actuator motor when changing between high and low beam. The actuator motor is integrated in the lamp housing.
There are three versions of the light switch function. These are programmed using the diagnostic tool:
- Low beam in all switch positions except the parking light position (flex zero)
- The light switch functioning on the basis of: off, parking light, low beam (flexsted)
- Low beam always on regardless of the position of the light switch (flexlgt).
To detect problems with the low beam, the central electronic module (CEM) reads the power consumption of the circuit. If this falls below a certain threshold value a fault will be indicated. The general warning lamp lights in the driver information module (DIM) and a text message is displayed.
For Bi-Xenon lamps there is a connection from the actuator motor to the central electronic module (CEM). In the event of incorrect values, the central electronic module (CEM) lowers the length of the beam using the headlamp range adjustment function.
There are diagnostics for the light switch and the relays.
There are also diagnostic for the high and low beam function (actuator motor) for Bi-Xenon lamps.
For further information about Bi-Xenon lamps, see Design and Function, Gas discharge lamps (GDL).

Parking lights / license plate lighting




There are a number of lamps positioned around the car to mark its position. These are in the headlamps, tail lamps and on the front fenders (US model). The lamps light together with the license plate lighting when the light switch module (LSM) is in parking lamp mode or low beam is on.
The lamps are powered via a directly connected relay on the central electronic module (CEM). The rear parking lamps are supplied with power via two shunts (mounted on the rear electronic module (REM)), one for each side. This is so that the power consumption can be monitored and any fault in the lamps detected. The faults are detected by the rear electronic module (REM).
There are diagnostics for the relay, the rear parking lamps (via the rear electrical module (REM)) and the light switch.

Headlamp range adjustment (certain markets)




There are two motors on the reverse of the headlamps. These angle the headlamps upwards or downwards to control the range of the beam.
The motors are controlled by a thumb wheel which is located in the light switch module (LSM) on the left of the dashboard. If the thumb wheel is turned, information is transmitted to the motors which adjust the headlamps accordingly.
There are diagnostics for the headlamp range adjustment.

Automatic range adjustment (Bi-Xenon)
There are two motors on the reverse of the headlamps. These angle the headlamps upwards or downwards to control the range of the beam.
The motors are controlled by signals from a position sensor at the rear axle. The sensor detects the angle of the car under different load conditions and sends this information so that the central electronic module (CEM) can determine whether the lamps need to be raised or lowered.
For further information about the inner roof lighting, see Design and Function, rear electronic module (REM).
There are diagnostics for the headlamp range adjustment.

Front fog lamps




If the car has front fog lamps, these are in the bumper casing below the headlamps.
The fog lamps are operated via a button in the light switch module (LSM). An LED in the button lights when the fog lamps are activated. The light switch transmits data via serial communication to the central electronic module (CEM). The lamps are powered via a directly connected relay on the central electronic module (CEM).
There are diagnostics for the fog lamp relay.

Turn signal lamps / Hazard warning signal flashers




There are six lamps around the car to indicate direction changes. These are located in the front and rear lights and on the sides of the car in front of the front doors.
The turn signal lamps are operated using the left-hand control stalk.
To cancel the hazard warning signal flashers, where all the turn signal lights flash, press in the button for the hazard warning signal flasher. This is positioned in the middle of the dashboard by the center air vents.
The central electronic module (CEM) supplies the lamps with power via two shunts. These are located on the relay box by the central electronic module (CEM). A signal is also sent to the bulb in the hazard warning signal flasher switch when this function is activated.
The central electronic module (CEM) monitors the power consumption on each side to check for bulb faults. If the power consumption falls below a certain threshold value, a fault is indicated and the frequency of the signal to the bulbs is doubled on the side of the blown lamp.
There are diagnostics for the shunts.

High-mounted stop lamp (S60/S80)




There is a high-mounted stop lamp above the rear windshield. This lamp lights during braking together with the standard stop lamps. It is activated when the switch on the brake pedal is closed.
The high level stop lamp is powered directly from the central electronic module (CEM). The lamp consists of a number of LEDs.
There are diagnostics for the high level stop lamp.

Courtesy lighting / key lighting / glove compartment lighting




There are various lamps inside the passenger compartment, such as the courtesy lighting and glove compartment lighting for example. There are also LEDs around the keyhole in the ignition switch.
The lamps for the courtesy lighting are in the soundproofing panels on the driver and passenger sides. For the backseat the lamps are in the doors (not V70/V70XC). The lamp for the glove compartment is positioned on the left-hand inner side.
The lighting time can be programmed via the upper electronic module (UEM). For further information, see Design and Function, upper electronic module (UEM).
There are only diagnostics for the keyhole lighting.

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 control 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.

Starter motor




The starter motor is on the left-hand side of the engine by the air cleaner (ACL) housing. The starter motor is powered directly from the battery. There is a solenoid on the starter motor to close the circuit. The central electronic module (CEM) activates a relay in the relay box in the engine compartment to act on the solenoid. This supplies the solenoid with power and closes the circuit for the starter motor.
The starter motor turns when the key is turned to position III in the ignition switch.
There are different functions which prevent starting, depending on whether the car has an automatic or manual transmission. The central electronic module (CEM) also has an electronic immobilizer function which communicates with a transponder in the key. For further information about electronic immobilizers, see Design and Function, Electronic immobilizer.
- Cars with manual gearboxes have a sensor in the clutch pedal. The clutch pedal must be depressed to allow starting (certain markets)
- In cars with type 4T65EV automatic transmissions, a signal is transmitted from the gear-shift position sensor to the transmission control module (TCM) which then sends a directly connected signal to the central electronic module (CEM)
- In cars with AW automatic transmissions, a directly connected signal is transmitted directly from the gear-shift position sensor to the central electronic module (CEM).
There are diagnostics for the relay for the starter motor.

Rear window lift mechanisms




The rear side windows are operated by motors in the doors. The switches for operating the windows are in the door panels. The windows can also be operated from the driver's door module (DDM).
The function is controlled by five relays on the central electronic module (CEM). Depending on whether the control switch is moved up or down, the relays are activated to carry out the requested operation.
Two relays guide the window up on the right and left-hand sides. Two different relays guide the window down. A further relay controls the power supply.
When operated from the driver's position, information is transmitted via the controller area network (CAN) from the driver's door module (DDM) to the central electronic module (CEM) which sends out signals to the relays.
There are diagnostics for the relays for the rear window lift mechanisms.

Fuel pump




The fuel pump (FP) is located on the inside of the fuel tank on the right-hand side. The pump is checked by the central electronic module (CEM) which operates a relay. This relay controls the power supply to the pump and is directly connected to the central electronic module (CEM).
The central electronic module (CEM) uses the controller area network (CAN) to communicate with the engine control module (ECM) to control the fuel pump (FP). There is also a hardwire connection between the engine control module (ECM) and the central electronic module (CEM). This is used to transmit a pulsed signal to operate the fuel pump (FP). This allows the pump to function if there is a fault in the controller area network (CAN).
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 fuel pump (FP).
There are diagnostics for the input signal from the engine control module (ECM) and for the relay for the fuel pump (FP).

Washer / wipers




The windshield wipers are powered by a motor positioned under the cowl. There are also headlamp wipers. There are also washer nozzles on the hood and bumper cover for cleaning the windshield and headlamps. The washer nozzles are connected to a pump motor on the windshield washer reservoir at the front right of the engine compartment.
For cars with five doors, there is a wiper and washer nozzle for the rear windshield. The washer nozzle is connected to a separate pump on the windshield washer reservoir.
The windshield wipers are operated using the right-hand control stalk. There are three positions: intermittent, low speed and high speed. The time between strokes for intermittent wiping is adjusted using a ring on the control stalk.
Pull the control stalk towards the steering wheel to clean the windshield. The washer and wipers for the headlamps are activated at the same time. The headlamp wipers operate for as long as washing is activated. They are not activated when only the windshield wipers are activated.
Push the control stalk away from the steering wheel to clean the rear windshield. There is a button at the end of the control stalk to control the rear wiper.
Information about the position of the control stalk is transmitted to the central electronic module (CEM) on the controller area network (CAN). The central electronic module (CEM) also receives a signal from the wiper motor if the wipers are in the park position.
The central electronic module (CEM) also monitors the windshield washer reservoir level via a level sensor in the reservoir. The switch in the level sensor closes if the level falls below one liter. A text message indicating that the windshield washer fluid needs to be topped up then lights in the driver information module (DIM).
The power supply for the rear windshield wiper is via a directly connected relay on the rear electronic module (REM). Other wipers and the washer motors are supplied with power via relays in the engine compartment.
There are diagnostics for the windshield wipers.

Heated seats (certain markets)




There are heater pads in the cushions and backrests to warm the seats. These are controlled by a control module under the seat. A thermistor on the heater pad detects the heat level.
The information between the control module and the central electronic module (CEM) is transmitted using serial communication. This data contains status information, diagnostic information and signals to control the heat level.
The seat heaters are operated using a switch to the right of the climate control module (CCM). The heat can be set to high or low. These temperatures can be programmed using the diagnostic tool.
There are diagnostics for the seat heaters.

Speed sensitive power steering




If the car has speed dependent power steering to control the steering assistance, there is a stepper motor which controls a hydraulic valve on the steering gear.
The stepper motor is operated by the central electronic module (CEM) and checked via four outputs in the central electronic module (CEM). Signals are transmitted from the central electronic module (CEM) to set the motor to the correct position for the speed of the car. The motor deploys the valve on the steering gear to the required degree and regulates the oil in the steering gear to reduce or increase the servo assistance. The steering assistance increases at lower speeds and is reduced at higher speeds.
There are diagnostics for the power steering.