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Home >> Land Rover >> 2012 >> LR4 HSE Lux >> Repair and Diagnosis (Single Page) >> Body & Frame >> Door Locks >> Anti-Theft - Passive >> Anti-Theft - Passive >> Description & Operation >> Anti-Theft - Passive >> Principles Of Operation >> Passive Start

Passive Start

At the request of the central junction box (CJB) the KVM (Keyless Vehicle Module) prompts each of the internal low-frequency antennas to output a signal. When the Smart Key is in the vehicle cabin, it detects the low-frequency signals and responds with a RF radio frequency data-identification signal back to the KVM via the RF receiver.

If the data received matches that stored in the KVM it continues the passive start process by communicating a 'Smart Key valid' signal to the central junction box (CJB) via the medium-speed controller area network (CAN) bus.

Once the central junction box (CJB) receives the authorization and confirms the response with an internal calculation, it passes coded data to the engine control module (ECM) on the high-speed controller area network (CAN) bus. Upon confirmation from the engine control module (ECM) the ignition is enabled.

Before central junction box (CJB) sends a mobilization signal to the engine control module (ECM) it will exchange encrypted data with the electric steering lock mechanism to authorize unlocking of the steering column. The instrument cluster only provides a ground for the steering lock motor.

The central junction box (CJB) will enable the fuel pump relay which, on diesel vehicles operates the fuel pump and on gasoline vehicles sends a battery voltage supply to the fuel pump driver module to operate the fuel pump in conjunction with the engine control module (ECM).

NOTE: If the KVM fails to locate the Smart Key, a message 'SMART KEY NOT FOUND REFER TO HANDBOOK' will appear in the instrument cluster message center and the keyless start back-up process will have to be used to mobilize and start the vehicle.

To ensure optimum long term reliability of the smart key the battery must be replaced with a brand new, unused battery. If a used battery is installed the "SMART KEY BATTERY LOW" message may not be cleared. To avoid contamination of the contacts the battery should be removed from its packaging and installed into the smart key while wearing gloves. To confirm that the replacement battery is working correctly press the unlock button twice while holding the smart key outside the vehicle, then enter the vehicle with the smart key, press the start button and confirm that the "SMART KEY BATTERY LOW" message is not displayed.