Engine control module (ECM) Volvo V70 II facelift

Engine control module (ECM)

Engine control module (ECM) (4/46) checks the ignition system in the vehicle. The engine control module (ECM) also grants permission to the central electronic module (CEM) if the starter motor is to be allowed to operate when attempting to start. The functions are activated after an approved check of the ignition key has been carried out and an approved identity check has been performed between the engine control module (ECM) and the central electronic module (CEM).

In order for the engine control module (ECM) to work in the immobilizer system, the control module must be programmed with codes. This takes place the first time during installation at the factory, and then if the control module is replaced (when downloading software).

For further information, see VIDA Design and Function, engine control module (ECM).

The driver information module (DIM) (5/1) receives information from the central electronic module (CEM) about which message is to appear in the display. A message will be displayed if there is a fault in any of the checks run by the system.

For further information, see VIDA Design and Function, driver information module (DIM).

The central electronic module (CEM) is the master unit for the immobilizer. The central electronic module (CEM) also directly stores diagnostic trouble codes (DTCs) for faults in the immobilizer system. Some other faults can also be stored in the engine control module (ECM).

For information about diagnostic functions, see VIDA Design and Function, central electronic module (CEM), and Design and Function, engine control module (ECM).

To increase the security of the immobilizer system, the central electronic module (CEM) and the engine control module (ECM) are linked to each other with codes. The codes must be programmed if a control module is replaced before the vehicle can be started. Programming replaced control modules takes place automatically when downloading software into the new control module.

Ignition keys can be added and erased. A maximum of 6 key IDs can be programmed into the central electronic module (CEM). When programming a key, the key is identified to the control module with a code that is stored in the control module memory.

When a key is programmed for the vehicle, the remote control code is also entered if this is to be linked to the vehicle. However, the remote control code has nothing to do with the immobilizer system. For further information, see VIDA Design and Function, central locking.

If a new key is added to a vehicle, the transponder in the key for this vehicle is locked and consequently cannot be programmed for another vehicle.

The erase function is used when the customer wishes to prevent one or more keys from being used to start the vehicle. The keys may have been stolen and could be traced back to the vehicle.

Note. The following applies for model year 2004: Ignition keys and remote controls are integrated. Therefore the code for the remote control and the transponder must be available when programming. These are programmed at the same time. This means that a key that has been erased can be programmed back into the same vehicle if both these keys are available. The codes are on the packaging in which the keys are supplied. If the codes are not available, a new ignition key must be ordered.

Keys are programmed via VIDA vehicle communication.

The function of the immobilizer is to make the vehicle unusable unless a genuine Volvo key that belongs to the vehicle is used. When the ignition key is turned to position II, a check is performed electronically to ensure that the correct key is being used. If the key is not approved, the engine will not start. The function of the system will not be noticed by the customer as long as an approved key is used and there are no faults.

Scheme 585

Deactivation

When the ignition key is turned to position II, the central electronic module (CEM) performs an identity check of the transponder in the key via the antenna ring. In response, the central electronic module (CEM) receives a code from the transponder, which is compared to the codes that are stored in the central electronic module (CEM). If the codes correspond, the key is approved.

At the same time, the central electronic module (CEM) activates the relay for the starter motor and commences an identity check between the central electronic module (CEM) and the engine control module (ECM). The engine control module (ECM) transmits a code to the central electronic module (CEM) and receives a code back. The central electronic module (CEM) also transmits the results of the key check to the engine control module (ECM). If the identity check between the engine control module (ECM) and the central electronic module (CEM) as well as the check on the key are OK, the engine control module (ECM) will transmit a command to the central electronic module (CEM) that the starter motor may be activated. The engine control module (ECM) will then also activate the ignition system.

Note. The engine control module (ECM) allows the starter motor to turn once the identity check between the engine control module (ECM) and the central electronic module (CEM) is complete. The starter motor will not be allowed to operate until the check on the ignition key is complete. Depending on the outcome of these two checks, the engine control module (ECM) will then determine whether the starter motor is to be allowed to operate.

If either of the checks fails, a message will appear in the display on the driver information module (DIM) and the engine will not start.

Activation

The immobilizer system is activated when the ignition key is turned to position 0 and the engine stops. The engine control module (ECM) then sends a command to the central electronic module (CEM) that the starter motor is no longer permitted to turn.

The immobilizer system contains safety functions for preventing the system from being activated in the event the engine should stop while the ignition is still switched on. In this case the engine control module (ECM) will wait for a while before a command is sent to the central electronic module (CEM) indicating that the immobilizer is to be activated. If an attempt is made to start the vehicle within this time, there will be no new communication between the engine control module (ECM) and the central electronic module (CEM).

The immobilizer system will neither be activated if the vehicle is still moving when the engine stops. Similarly, the engine will not stop if the engine control module (ECM) conducts an internal restart while driving.

If the ignition key is turned to position 0 but the key is not removed from the ignition switch, the engine control module (ECM) will wait for a while but then send a command to the central electronic module (CEM) to activate the immobilizer, despite the fact that the key has not been removed from the ignition switch.

Two different error messages may be displayed in the Driver information module (DIM) display for the immobilizer function

Note. Because the information is sensitive to change the exact wording cannot be written here.

1. Message regarding fault in the system for the immobilizer with reference to the user manual. The message is displayed when a problem has occurred in communication between the Central electronic module (CEM) and the Engine control module (ECM).
2. Message regarding prevented start with new attempt request. The message is displayed if a fault has occurred when reading the transponder in the key.

For further information, see Diagnostic trouble code (DTC) information for the relevant diagnostic trouble codes (DTCs) in the Information manager.

Scheme 586

The immobilizer system increases the level of the vehicle safety system by making it extremely difficult to use the vehicle unless a valid key, which belongs to the vehicle, is used to start it. The identity of the key is checked when the vehicle is started, and if the key is not approved the engine will not start. The customer will not notice this function as long as a valid key is used an no fault occurs.

The immobilizer system includes

1. Central electronic module (CEM)
2. Engine control module (ECM)
3. Antenna ring
4. Driver information module (DIM).

Definitions

Activated system: The system means that the vehicle cannot be started.

Deactivated system: The key has been checked and approved. The system permits the car to start.

The tables below summarize the input and output signals to the units in the system for the immobilizer. The signal types are divided into directly connected signals, serial communication and controller area network (CAN) communication.

Central electronic module (CEM) (4/56)

Antenna ring (16/65)

Engine control module (ECM) (4/46)

Driver information module (DIM) (5/1)

Scheme 587

Note. The illustration above and the table below is an example that shows model year 2007. All other information in the document is general and applies to all model years.