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Home >> Volvo >> 2012 >> C30 R Design L5-2.5L Turbo VIN 67 B5254T7 >> 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.
- In the USA/CAN market, the clutch pedal must be pressed on vehicles with manual transmissions
- During passive starting (cars with the keyless entry system only), the brake pedal must be pressed on vehicles with automatic transmissions or the clutch pedal on vehicles with manual 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 car from being used if a non Volvo original key for that vehicle is used to start the car. The identity of the key is checked electronically when the key is inserted. On cars with the keyless system it is checked by the keyless vehicle module (KVM). If the key is not approved, the steering wheel 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 key is used an no fault occurs.

Remote-controlled immobilization
Applies for the English, Dutch, and Belgian market. A special version with stricter requirements is available for 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 (only cars without the keyless entry)
When the key is inserted in the ignition switch, the key blade acts on the key-in switch. The key-in switch then forwards 12V from the battery to the central electronic module (CEM) and to the communication circuit in the start control module (SCU). The central electronic module (CEM) then activates the fuel pump (FP). When the signal is received by the central electronic module (CEM), it sends this command to the start control module (SCU) instructing it to check the key. The start control module (SCU) activates the antenna ring and reads off an identification code from the key transponder. This code is transmitted to the central electronic module (CEM) and compared with the codes programmed in the central electronic module (CEM).
If the vehicle has an Alcohol Analyzing Start Inhibitor (option 2009-), an approved breath test must be performed in order for the Alcohol Analyzing Start Inhibitor handheld unit to send an approved signal to the Central electronic module (CEM) via the Remote Receiver Module (RRX). For further information see Design and Function, Alcohol Analyzing Start Inhibitor.
If the key is approved, the central electronic module (CEM) transmits a command to the steering column lock module (SCL) to unlock the steering wheel lock. The vehicle cannot be started before the spring bolt in the steering column lock module (SCL) is in the unlocked position. The immobilizer system contains several safety functions to ensure that the steering wheel lock does not lock while driving.

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 steering wheel lock is unlocked, the communication between the central electronic module (CEM) and engine control module (ECM) is checked. This is to ensure that the correct codes are programmed into both control modules. The engine control module (ECM) also checks the identity of the brake control module (BCM) by reading off its serial number. This number is compared with the number programmed into the engine control module (ECM). If these checks are completed satisfactorily, the engine control module (ECM) activates the ignition system. The engine control module (ECM) also transmits a command to the central electronic module (CEM) to allow the fuel pump (FP) to continue to run. If a fault should occur or a check is not approved, the engine control module (ECM) instructs the central electronic module (CEM) to deactivate the fuel pump (FP). The engine control module (ECM) also checks the other parameters covered by the start inhibition function. If all conditions are met, the 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 inbuilt 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)
The key-in switch is activated when the starter button is pressed in. The keyless vehicle module (KVM) then scans for a passive key inside the vehicle. At the same time, the central electronic module (CEM) transmits an encrypted request to the keyless vehicle module (KVM). This request is responded to only if an approved passive key has been registered. If a key is found, the keyless vehicle module (KVM) checks that the key is approved. If this is the case, the keyless vehicle module (KVM) transmits a response to the central electronic module (CEM) indicating that the key is approved.
If a passive key is not registered, the keyless vehicle module (KVM) will transmit a negative response to the central electronic module (CEM). The central electronic module (CEM) will then transmit a request to the start control module (SCU) instead to search for a transponder. The central electronic module (CEM) will approve the key if a transponder is found.
If the key is approved, the central electronic module (CEM) transmits a command to the steering column lock module (SCL) to unlock the steering wheel lock. The vehicle cannot be started before the spring bolt in the steering column lock module (SCL) is in the unlocked position. The immobilizer system contains several safety functions to ensure that the steering wheel lock does not lock while driving.

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 steering wheel lock is unlocked, the communication between the central electronic module (CEM) and engine control module (ECM) is checked. This is to ensure that the correct codes are programmed into both control modules. The engine control module (ECM) also checks the identity of the brake control module (BCM) by reading off its serial number. This number is compared with the number programmed into the engine control module (ECM). If these checks are completed satisfactorily, the engine control module (ECM) activates the ignition system. The engine control module (ECM) also transmits a command to the central electronic module (CEM) to activate the fuel pump (FP). The engine control module (ECM) also checks the other parameters covered by the start inhibition function. If all conditions are met, the 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 inbuilt diagnostic test modes (DTM) to ensure that the engine can be restarted after unintentional stops.

Activation
The immobilizer system is activated when the ignition is switched off. The engine cannot be started when the system is activated. The engine control module (ECM) then deactivates the ignition system and the relay for the starter motor. The central electronic module (CEM) deactivates the fuel pump (FP) and sends a command to the steering column lock module (SCL) to lock the steering wheel lock. As a safety precaution, the steering wheel lock cannot be locked before the central electronic module (CEM) receives an indication that the vehicle is stationary and the engine off. The engine control module (ECM) transmits the status of the engine to the central electronic module (CEM). The central electronic module (CEM) uses the signals on the controller area network (CAN) from the brake control module (BCM) or transmission control module (TCM) to check that the vehicle is not moving.

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.

Key lock
The key lock function is part of the security system. This function means that the key cannot be removed from the ignition switch (it cannot be turned from position I to 0) if the gear selector is not in the park (P) position. This applies only to vehicles with automatic transmissions.
This function is checked by the central electronic module (CEM). The start control module (SCU) contains a coil which is powered by the central electronic module (CEM). The central electronic module (CEM) receives a signal from the transmission control module (TCM) indicating the position of the gear selector. The key can be turned when the coil has been activated. The key cannot be turned if the coil is not activated.

Key warning
The key warning function is part of the security system (applies to USA/CAN only). The components in the function are the central electronic module (CEM) and the driver information module (DIM). The warning is activated if the driver's door is opened whilst the key is in the ignition switch. A contact breaker in the lock unit in the driver's door indicates that the door has been opened.
If the system for keyless functions is installed, the antennas inside the vehicle are activated each time the driver's door is opened. The system then scans for the key which was used to start the vehicle. A warning message is displayed in the driver information module (DIM) if this key is not found. The engine will continue running, but if the key is turned to position 0 the engine will not start again if there is not another valid key inside the vehicle.

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 central electronic module (CEM) and steering column lock module (SCL) are part of the steering wheel lock function. The power supply to the steering column lock module (SCL) is controlled by the central electronic module (CEM). The steering column lock module (SCL) also receives commands from the central electronic module (CEM) to lock or unlock the steering wheel lock. The function of the steering wheel lock is limited when the vehicle is stationary and the engine is off.
Whilst the vehicle is being driven, the central electronic module (CEM) monitors the communication cable to the steering column lock module (SCL). If the central electronic module (CEM) detects that the steering column lock module (SCL) starts communicating when it should not be powered, the central electronic module (CEM) will display an warning message in the driver information module (DIM) and will attempt to disengage the steering column lock.

Unlocking
If the keyless vehicle module (KVM) (cars with the keyless entry system only) and central electronic module (CEM) receive a signal from the key-in switch, the identity of the key is checked. This is done either via the keyless system or via the ignition switch. At the same time, the central electronic module (CEM) activates the power supply to the steering column lock module (SCL). After approved validation of the key, the central electronic module (CEM) checks that the engine is not running via CAN signals from the engine control module (ECM). The central electronic module (CEM) also checks that the vehicle is not moving via the CAN signals from the brake control module (BCM) or transmission control module (TCM). If the conditions are met, the central electronic module (CEM) transmits an unlock command to the steering column lock module (SCL). The steering column lock module (SCL) then attempts to unlock the steering wheel lock. If everything is OK, the steering column lock module (SCL) transmits two signals back to the central electronic module (CEM). One signal indicates that the steering column lock module (SCL) has not detected any internal faults and is functioning as intended. The other signal indicates that the spring bolt has moved to the unlocked position. The central electronic module (CEM) will then store an internal value for successful unlocking and then continues with the checks for the immobilizer system.
If the steering wheel lock does not unlock the first time, the steering column lock module (SCL) will make a further two unlocking attempts. 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 entry system
Whilst the vehicle is in use, the central electronic module (CEM) checks the input signals from the contact breakers for the start control module (SCU) which indicate the position of the ignition key. When the central electronic module (CEM) detects via these contact breakers that the ignition key has been turned to the 0 position and removed from the ignition, the central electronic module (CEM) initiates a locking sequence.
The following applies to vehicles with the keyless entry system
Whilst the vehicle is in use, the central electronic module (CEM) checks the input signals from the contact breakers for the start control module (SCU) which indicate the position of the starter button. When the central electronic module (CEM) detects, via these contact breakers, that the starter button has been turned to the 0 position and the key-in switch has been deactivated, the central electronic module (CEM) is ready to initiate a locking sequence. During passive starting, the steering column lock is not engaged before the driver's door is opened for safety reasons.

The central electronic module (CEM) then checks that the engine is not running via the CAN signals from the engine control module (ECM). The central electronic module (CEM) also checks that the vehicle is not moving via the CAN signals from the brake control module (BCM) or transmission control module (TCM). If the conditions are met, the central electronic module (CEM) powers the steering column lock module (SCL) and then transmits a lock command to it. The steering column lock module (SCL) sends signals back indicating whether locking was successful or not. The central electronic module (CEM) will store a diagnostic trouble code (DTC) if locking has failed after 3 attempts.

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