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Home >> Volvo >> 2010 >> XC70 AWD L6-3.0L Turbo VIN 99 B6304T2 >> Repair and Diagnosis >> Accessories and Optional Equipment >> Antitheft and Alarm Systems >> Description and Operation >> Immobilizer/Start Inhibition >> Function

Function






Function

Start inhibition
The start inhibition system is a comprehensive function of the security system. The start inhibition system compiles a number of parameters from the various security functions in the vehicle and then determines whether a start attempt is permitted. The checks that are run are:
- Checking depressed pedals.
- The clutch pedal must be depressed on vehicles with manual transmissions.
- The brake pedal must be depressed on vehicles with automatic transmissions.
- Checking the position of the gear selector. On cars with automatic transmissions, the gear selector must be in position P (park) or N (neutral).
- Checking the immobilizer. All checks run by the immobilizer must be OK.
- Checking the steering column lock. The steering column lock must be unlocked.
The function for start inhibition is checked by the engine control module (ECM). This function is based entirely on signals on the controller area network (CAN). For further information about the start process, see Design and Function, engine control module (ECM).

Immobilizer system
The immobilizer system prevents the vehicle from being used if a non Volvo original key for that vehicle is used to start the vehicle. The identity of the remote key is checked electronically when to ensure that the correct remote key is inserted in the Start control module (SCU). On cars with the keyless system it is checked by the keyless vehicle module (KVM). If the remote key is not approved, the steering column lock will not be unlocked and the engine will not start. The customer will not notice the function of the system as long as a valid remote key is used and no fault occurs.

Remote-controlled immobilization
Applies to the English, Dutch, and Belgian market. A special version with stricter requirements applies to the Brazilian market. Applies from and incl. structure week 201020.
On certain markets there is a function for remote-controlled immobilization and mobilization. The purpose of the function is to nullify the vehicle's programmed keys in case the vehicle is stolen, for example. The vehicle can be immobilized and mobilized either using Volvo On Call service center or via diagnostic commands in VIDA. For certain markets vehicles can only be mobilized by Volvo On Call service center.
If the vehicle is running when immobilization is requested, the vehicle is immobilized at the next start attempt. Central electronic module (CEM) can, in certain markets, request immobilization if the module detects that Phone module (PHM) does not answer to communication.
The function remote-controlled immobilization is diagnosed by Central electronic module (CEM). Immobilization and mobilization of vehicles via diagnostic commands takes place via Phone module (PHM).

Deactivation and start (only cars without the keyless locking system)




To deactivate the immobilizer system, the remote key must be inserted in the Start control module (SCU) (3/132). When the remote key is inserted in the Start control module (SCU), the Central electronic module (CEM) (4/56) transmits the command to the Start control module (SCU) that the remote key identity must be checked. The Start control module (SCU) activates the antenna and reads off the identity code from the remote key's transponder. This code is transmitted to the Central electronic module (CEM) and compared with the codes that are programmed in the Central electronic module (CEM). If the read off code from the remote key is in the Central electronic module (CEM), the key is approved.
If the vehicle has an alcolock (option 2008-), an approved breathalyzer test must be performed in order for the handset unit to send an approved signal to the Central electronic module (CEM) to work via the Remote Receiver Module (RRX).
For further information, see Design and Function, Alcohol Analyzing Start Inhibitor
Central electronic module (CEM) will then activate voltage supply to the fuel pump module (PEM).
Central electronic module (CEM) will, after approval of the remote key, check the signals on the CAN-net regarding the vehicle's speed and the engine's status.
If the vehicle is at a standstill and the engine is not running, the Central electronic module (CEM) will activate voltage feed to Steering column lock module (SCL) (4/102) via an internal relay in Central electronic module (CEM), and then send a command to Steering column lock module (SCL) to unlock the steering column lock.
The vehicle cannot be started until the lock bolt in Steering column lock module (SCL) is in unlocked position. The lock bolt's position is indicated by a switch located in Steering column lock module (SCL) and is connected to Central electronic module (CEM).
If Central electronic module (CEM) should detect that voltage feed to Steering column lock module (SCL) for some reason should become high during driving, a warning message is shown in Driver information module (DIM).

Note! The steering column lock module (SCL) is only available on model year 2004-2008 for the USA/CDN market and model year 2004- for other markets.

When the ignition is turned on or a start attempt is made (by pressing down a pedal and pressing the start button), the communication is checked between Central electronic module (CEM) and Engine control module (ECM).
Checking is performed to ensure that the correct codes are programmed in both control modules. Engine control module (ECM) also performs a check of the identity of Brake control module (BCM) (4/16) by reading out the serial number from Brake control module (BCM).
This number is compared to a programmed number in Engine control module (ECM).
If these checks are performed correctly, then Engine control module (ECM) activates the ignition system. Engine control module (ECM) also sends a command to Central electronic module (CEM) that the fuel pump should be permitted to continue to operate. Should a problem arise or a check is not approved, then Engine control module (ECM) will order Central electronic module (CEM) to deactivate the fuel pump. Engine control module (ECM) also checks the other parameters that are covered by the function for start inhibitor. If all conditions are fulfilled, then Engine control module (ECM) activates the relay for the starter motor. The engine can then be started.
If any of the above steps should fail, the engine will not start and a message will be displayed in the driver information module (DIM).
The immobilizer system has built-in diagnostic test modes (DTM) to ensure that the engine can be restarted after unintentional stops.

Passive deactivation and start (only cars with the keyless locking system)




To carry out a start of a keyless vehicle, a pedal must be depressed (clutch (MAN) or brake (AUT)) and the starter button pushed. When the starter button is pushed, an input on the keyless vehicle module (KVM) (4/93) is grounded, which searches for a remote key with passive function in the vehicle. Ground connection from the starter button also goes to the Central electronic module (CEM) (4/56), which, at the same time, transmits an encrypted request to the Keyless vehicle module (KVM). This request is responded to only if an approved passive remote key has been registered. If a remote key is found, the keyless vehicle module (KVM) checks that it is approved. If this is the case, the keyless vehicle module (KVM) transmits a response to the central electronic module (CEM) indicating that the remote key is approved.
If a passive remote control key cannot be found then the central electronic module (CEM) will instead send a request to the start control module (SCU) (3/132) to scan for a transponder. If an approved transponder is identified then the central electronic module (CEM) will approve the key.
If a start attempt is made, either non-keyless or keyless, the Central electronic module (CEM) will check the signals on the CAN-net regarding the vehicle's speed and the engine's status.
If the vehicle is at a standstill and the engine is not running, then Central electronic module (CEM) will activate voltage feed to Steering column lock module (SCL) (4/102) via an internal relay and will then send a command to Steering column lock module (SCL) to unlock the steering column lock.
The vehicle cannot be started until the lock bolt in Steering column lock module (SCL) is in its unlocked position.
The lock bolt's position is indicated by a switch located in Steering column lock module (SCL) and is connected to Central electronic module (CEM). During driving, continuous checking is performed of the Central electronic module (CEM) to make sure that the steering column lock is not activated accidentally.
If Central electronic module (CEM) should detect that voltage feed to Steering column lock module (SCL) for some reason should become high during driving, a warning message is shown in Driver information module (DIM).

Note! The steering column lock module (SCL) is only available on model year 2004-2008 for the USA/CDN market and model year 2004- for other markets.

When the ignition is turned on or a start attempt is made (by pressing down a pedal and pressing the start button), the communication is checked between Central electronic module (CEM) and Engine control module (ECM).
Checking is performed to ensure that the correct codes are programmed in both control modules.
Engine control module (ECM) also checks the identity of Brake control module (BCM) (4/16) by reading out the serial number from Brake control module (BCM). This number is compared to a programmed number in Engine control module (ECM).
If these checks are performed correctly, then Engine control module (ECM) activates the ignition system. Engine control module (ECM) also sends a command to Central electronic module (CEM) that the fuel pump should be permitted to continue to operate.
Should a problem arise or a check is not approved, then Engine control module (ECM) will order Central electronic module (CEM) to deactivate the fuel pump. Engine control module (ECM) also checks the other parameters that are covered by the function for start inhibitor.
If all conditions are fulfilled, then Engine control module (ECM) activates the relay for the starter motor. The engine can then be started.
If any of the above steps should fail, the engine will not start and a message will be displayed in the driver information module (DIM).
The immobilizer system has built-in diagnostic test modes (DTM) to ensure that the engine can be restarted after unintentional stops.

Activation
System for immobilizer is activated when the ignition is turned off.
Engine start is prevented when the system is activated. Engine control module (ECM) deactivates the ignition system and prevents the relay for the starter motor to be activated. Central electronic module (CEM) will deactivate the fuel pump at the same time.
If the driver door is opened, Central electronic module (CEM) will check the signals on the CAN-net regarding the engine's status and vehicle speed. If the engine is off and the vehicle is at a standstill the Central electronic module (CEM) will activate voltage feed to Steering column lock module (SCL) and thereafter send command for the steering column lock to be locked.

Note! The steering column lock module (SCL) is only available on model year 2004-2008 for the USA/CDN market and model year 2004- for other markets.

Remote key lock
Included in the security system is the function for locking the remote key in the Start control module (SCU). This function means that the remote key cannot be removed if the gear selector is not in the park (P) position.(only cars with automatic transmissions).
The vehicle must be stationary and the engine switched off in order for the remote control key to be removed (applies to vehicles both with and without automatic transmission).
This function is checked by the central electronic module (CEM). The Start control module (SCU) contains a contact breaker that closes when the remote key is pressed to the limit position in the Start control module (SCU). The contact breaker indicates to the Start control module (SCU) that the motor for insertion and ejection of the remote key must be activated to draw in or eject the remote key. The Central electronic module (CEM) continually checks if remote key ejection is permitted by checking the signals for:
- engine status from the Engine control module (ECM)
- gear selector position from the Transmission control module (TCM)
- vehicle speed from the Brake control module (BCM).
A message is transmitted at regular intervals to the Start control module (SCU) about whether the remote key can be removed or not. If the remote key is inserted and ejection is permitted according to the Central electronic module (CEM), the Start control module (SCU) activates the motor for insertion and ejection. If the gear selector is not in position P, a message is displayed in the Driver information module (DIM), with a request to shift the gear selector to the P position. The remote key will not be ejected.

Key warning
The key warning function is part of the security system. For vehicles without the keyless function there is only key warning on vehicles on the USA/CDN market. The components in the function are the central electronic module (CEM) and the driver information module (DIM). The warning activates when the driver's door is opened when the remote key is in the Start control module (SCU). A contact in the lock unit of the driver's door indicates that the driver's door was opened.
If the system for keyless functions is installed, the antennas inside the vehicle are activated each time the last door is closed. The system then scans for the valid remote key. A warning message is displayed in the driver information module (DIM) if no valid remote key is not found. The engine will continue running, but if the engine is switched off it will not start again if there is not another valid remote control key inside the vehicle.
If the system for keyless functions is installed, the antennas inside the vehicle are activated each time the last door is closed. The system then scans for the remote control key which was used to start the vehicle. A warning message is displayed in the driver information module (DIM) if this remote control key is not found. The engine will continue running, but if the engine is switched off it will not start again if there is not another valid remote control key inside the vehicle.
For vehicles with the keyless function the signal is also activated and a message is displayed in the Driver information module (DIM) if the vehicle is in any other ignition position than "ignition off" when the driver's door is opened and the engine is switched off.

Steering column lock

Note! The steering column lock module (SCL) is only available on model year 2004-2008 for the USA/CDN market and model year 2004- for other markets.

The function for the steering column lock is made up by Central electronic module (CEM) and Steering column lock module (SCL). Voltage feed to Steering column lock module (SCL) is controlled by Central electronic module (CEM) via an internal relay in Central electronic module (CEM).
From the Central electronic module (CEM) the Steering column lock module (SCL) also receives commands about when the steering column lock is to be locked or unlocked. The steering column lock is only permitted to perform any function when the vehicle is not moving and the engine is off.
While driving, checks are performed by Central electronic module (CEM) to make sure that the steering column lock is not activated accidentally. At the same time, the Central electronic module (CEM) monitors the communication cable to Steering column lock module (SCL).
If Central electronic module (CEM) detects that Steering column lock module (SCL) begins to communicate when Steering column lock module (SCL) really should have been without voltage, then Central electronic module (CEM) will show a warning message in the display in the Driver information module (DIM) and try to turn off the steering column lock.
Unlocking
When Central electronic module (CEM) receives a signal from the start button (applies to vehicles with keyless function) or when the remote key is pressed into the Start control module (SCU), a check is performed of key identity, either via the keyless system or via Start control module (SCU).
After key validation is complete with approved result, the Central electronic module (CEM) activates voltage feed to Steering column lock module (SCL). During this time, Central electronic module (CEM) performs checks of signals from Engine control module (ECM) and Brake control module (BCM) that the engine is not running and that the vehicle is not moving.
If Central electronic module (CEM) determines that the conditions for unlocking the steering column lock are fulfilled, then Central electronic module (CEM) issues an unlock command to Steering column lock module (SCL). Then Steering column lock module (SCL) attempts to unlock the steering column lock.
If unlocking is successful, Steering column lock module (SCL) sends two signals back to Central electronic module (CEM). One indicates that Steering column lock module (SCL) has not detected any internal problems and works as intended. The other indicates that the lock bolt has reached its unlocked position.
Central electronic module (CEM) will then store a value internally that unlocking has been successful, and will continue to perform the checks that are done for system for immobilizer.
If the steering column lock does not unlock the first time, the steering column lock module (SCL) will make a further two unlocking attempts. The power supply to the Steering column lock module (SCL) is switched off between each attempt. If these also fail, the steering column lock module (SCL) will transmit a message about the fault to the central electronic module (CEM). The central electronic module (CEM) will then store a diagnostic trouble code (DTC) and the checks for the immobilizer system will be cancelled. It will not then be possible to start the engine.
Locking
The following applies to vehicles without the keyless locking system:
The Central electronic module (CEM) receives a ground connection from the contact breaker in the Start control module (SCU) that indicates that the remote key has been pushed to its limit position when it is o be removed from the Start control module (SCU). When the signal is received, the Central electronic module (CEM) checks the signals on CAN that:
- the engine is switched off, from the Engine control module (ECM)
- the vehicle is stationary, from the Brake control module (BCM).
If the engine is switched off and the vehicle does not move then the central electronic module (CEM) will activate the voltage feed to the steering column lock module (SCL). The central electronic module (CEM) will then send signals via LIN to the steering column lock module (SCL) with information that the engine is switched off and that the vehicle is stationary. The central electronic module (CEM) then waits for a reply from the steering column lock module (SCL) that the signals are approved and then sends a message to the steering column lock module (SCL) that locking should be implemented.
Steering column lock module (SCL) sends a message back to Central electronic module (CEM) about if locking was successful or not. If locking still has failed after 3 attempts, then Central electronic module (CEM) will generate a diagnostic trouble code.
Locking
The following applies to vehicles with the keyless locking system:
After the ignition has been switched off and the driver's door opened, the Central electronic module (CEM) checks the signals on CAN that:
- the engine is switched off, from the Engine control module (ECM)
- the vehicle is stationary, from the Brake control module (BCM).
If the engine is switched off and the vehicle does not move then the central electronic module (CEM) will activate the voltage feed to the steering column lock module (SCL). The central electronic module (CEM) will then send signals via LIN to the steering column lock module (SCL) with information that the engine is switched off and that the vehicle is stationary. The central electronic module (CEM) then waits for a reply from the steering column lock module (SCL) that the signals are approved and then sends a message to the steering column lock module (SCL) that locking should be implemented.
Steering column lock module (SCL) sends a message back to Central electronic module (CEM) about if locking was successful or not. If locking still has failed after 3 attempts, then Central electronic module (CEM) will generate a diagnostic trouble code.

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