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Home >> Volvo >> 2007 >> S60 2.5T AWD L5-2.5L Turbo VIN 59 B5254T2 >> Repair and Diagnosis >> Body and Frame >> Body Control Systems >> Description and Operation >> Central Electronic Module (CEM) >> Function >> Part 2

Part 2






Function (Continued)

Starter motor





Manual transmissions
The starter motor (6/25) is operated by turning the key in the ignition switch (3/1) to position III.
- For transmissions with a clutch interlock (certain markets), a signal is transmitted from the ignition switch to the engine control module (ECM) (4/46). The engine control module (ECM) detects the position of the clutch pedal sensor (7/123). The engine control module (ECM) transmits data to the central electronic module (CEM) (4/56) via the control area network (CAN) about the position of the pedal. The central electronic module (CEM) requires a signal that the clutch is pressed down and that the key is in position III before it will send a signal to the relay (2/35). When the relay is activated, the solenoid in the starter motor is powered
- For transmissions without clutch interlock, the central electronic module (CEM) (4/56) activates relay 2/35 and powers the solenoid in the starter motor (6/25).
The starter motor turns for as long as the key is in position III. If the engine has been started once, there is a Limp Home function so that the engine can be started again even if there is a fault in the control area network (CAN). This function is active for a brief period after the key is removed from the ignition switch. After this time the car will not start because there is no communication for the immobilizer between the central electronic module (CEM) and the engine control module (ECM).

Automatic transmission
The starter motor (6/25) is operated by turning the key in the ignition switch (3/1) to position III.
- For transmission 4T65EV, a signal is transmitted from the gear-shift position sensor (3/71) via the transmission control module (TCM) (4/28) to the central electronic module (CEM) (4/56) indicating that the gear selector is in position P/N
- For AW transmissions the signal is transmitted directly from the gear-shift position sensor to the central electronic module (CEM). The central electronic module (CEM) requires this signal and a signal indicating that the key is in position III before it will send a signal to the relay (2/35). When the relay is activated, the solenoid in the starter motor is powered.
The starter motor turns for as long as the key is in position III. If the engine has been started once, there is a Limp Home function so that the engine can be started again even if there is a fault in the control area network (CAN). This function is active for a brief period after the key is removed from the ignition switch. After this time the car will not start because there is no communication for the immobilizer between the central electronic module (CEM) and the engine control module (ECM).

Speed sensitive power steering




The central electronic module (CEM) (4/56) receives information that the engine is running from the engine control module (ECM) (4/46) on the controller area network (CAN). It receives information about vehicle speed from the brake control module (BCM) (4/16). The central electronic module (CEM) then controls the power steering control module which in turn acts on the solenoid.
The central electronic module (CEM) checks the signals. If a fault is detected, the servo assistance is set to normal (approximately 70 km/h) and the system is disengaged. The central electronic module (CEM) also transmits a signal to the driver information module (DIM) (5/1) via the control area network (CAN) which lights the general warning lamp and displays a text message.

Description of function of the operating status of the heater
The heater can have a number of different statuses. Each status and what should occur in it is described below.





The vehicle configuration can be read off to check what functions the car is equipped with. The following affect the function of the heater:
- Parking and additional heater function or additional heater function only (diesel engines)
- Parking heater or not (gasoline engines)
- Residual heater or not
- Electrical engine block heater (time controlled via the driver information module (DIM)) or not.

Fuel driven parking heater




The driver sets the desired departure time using one of the two timer functions in the display on the driver information module (DIM) (5/1). The time is programmed by twisting the ring on the control stalk and by pressing the "reset" button for the desired time (timer 1, timer 2 or direct start). Direct start can also be used to start the heater.
The central electronic module (CEM) (4/56) receives data about when the driver wants to drive from the control stalk module (steering wheel module (SWM)) (3/254) and the driver information module (DIM).
The central electronic module (CEM) calculates when the heater needs to start so that it is warm enough in relation to the outside temperature. Information about temperature is obtained from the outside temperature sensor in the right-hand door mirror. This sensor is connected to the driver door module (DDM) or passenger door module (PDM).
The central electronic module (CEM) calculates when the heater needs to start:
- The heater calculates when start is required (15-50 minutes before the intended departure at medium low temperatures between -10 °C and +15 °C)
- This procedure takes a maximum of one minute. 60 minutes at temperatures below -10 °C
- This running time of the heater is a minimum of 15 minutes before the planned departure. (Warm temperatures between +15 °C and +25 °C).
When the heater is started directly using the control stalk it runs until it is shut off or for a maximum of 60 minutes. The heater is on for 10 minutes after the set time to allow for the driver getting to the car late.
A text message is displayed in the driver information module (DIM) when the heater is running.

Electrical heater with timer function




The desired departure time is set using the steering wheel module (SWM) (3/254).
The central electronic module (CEM) (4/56) calculates when the heater needs to start. The heater starts 2 hours and 45 minutes before the set departure time, irrespective of the temperature. A text message is displayed in the driver information module (DIM) (5/1) when the electrical heater is running.
The accessory electronic module (AEM) (4/78) electrically controls when the heater should be switched on and off. The engine block heater must be connected to a wall socket. The accessory electronic module (AEM) activates a relay which closes the switch for a heater element.

Residual heater




This function can be ordered as an accessory. See Reading off vehicle configuration data to check whether the car has a residual heater.
The function is activated in the driver information module (DIM) (5/1) using the control stalk (compare to the parking heater). Information about activation is sent to the central electronic module (CEM) (4/56) and climate control module (CCM) (3/112). The blower fan and damper settings are set by the climate control module (CCM). The central electronic module (CEM) transmits data to the combustion preheater module (CPM) (4/7) instructing it to activate the water pump.
When the residual heater is activated it will operate as long as the coolant temperature is above 30 °C or for a maximum of 20 minutes or until the function is switched off.
This function is used when the coolant is already warm. The coolant pump is started thereby circulating the coolant. The heat is distributed from the coolant to the passenger compartment unit in the climate control unit and on to the passenger compartment.
When the residual heater is running, the passenger compartment is heated by the climate control module (CCM) controlling the fan and damper according to a customer parameter (Applies only to electronic climate control (ECC)). This parameter is used to set the distribution between the defroster and the floor. The normal setting is 30% defroster and 70% floor.

Additional heater




The additional heater is standard in cars with diesel engines (certain markets). This function is used for cars in cold markets to provide extra heat to the climate control module. The heater functions in the same way as the parking heater although the start conditions are different. This is controlled by the central electronic module (CEM) (4/56). There is no physical difference between the parking heater and the additional heater. The difference between the functions is in the software.

Additional heater and parking heater




If a diesel engine car has a parking heater, the car will have both the additional heater and parking heater functions.
If the parking heater has been programmed and the driver comes to the car earlier than anticipated, the additional heater will not engage until the car is started. The additional heater then determines if the heater should be on or off, even if the driver attempts to disengages the heater using the control stalk.

Starting the heater remotely




Cars with an accessory electronic module (AEM) (4/78) can have a remote start function for the heater. This allows the heater to be started using a pager. A stop or start signal is transmitted from the accessory electronic module (AEM) to the central electronic module (CEM) (4/56) to start or stop the heater (4/7). This function is available for both fuel driven and electrical heaters.

Blind spot information system (BLIS)




The cameras take 30 images a second and compare each image with the previous one to check whether any changes have taken place. To be able to determine whether a change is of any significance when moving sideways, the camera module also has to know the vehicle's speed. To calculate the vehicle's speed and know whether the vehicle is turning, the speed signals for the respective rear wheels from the brake control module (BCM) are used. The central electronic module (CEM) (4/56) receives information from the brake control module (BCM) (4/16) via the CAN network on the respective speeds of the two rear wheels. These two signals are then passed on to the left camera module (LCM) and right camera module (RCM) respectively via serial communication.
If the camera module discovers that there is something in the dead angle, an orange LED, located on the inside of the panel at the front of the window on the door, comes on. This LED is directly connected to the respective camera module.
The blind spot information system (BLIS) can be deactivated using one of the switches on the dashboard environment panel. When this switch is depressed, a signal is transmitted from the climate control module (CCM) to the central electronic module (CEM) via the CAN network. The system is then deactivated until the switch is depressed again or the next time the vehicle is started.
If a fault is detected by the central electronic module (CEM), a diagnostic trouble code (DTC) is stored and a signal is transmitted via the CAN network to the driver information module (DIM), which turns on a general warning lamp and displays a text message.

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