Interesting facts on the Passive Entry & Passive Start systems for the 2010MY Range Rover, Range Rover Sport & LR4
Found in the Range Rover Sport & LR4 – the Passive Entry system allows the vehicle to be unlocked/locked without the physical use of a key, although the key is a functional component of the passive entry/start system. Once the key is within range of the vehicle (~1m) you can open the locked doors by just pulling the door handles (which now hold a capacitive plate – see #3 below). Re-locking is accomplished by pressing the button that resides near where you would normally insert a key in the door handle – this is called passive locking.
Interesting fact #1:
If single-point entry is the current security setting and a door other than the driver’s door is opened first, then all doors will be unlocked. If the driver’s door is opened, only the driver’s door will be unlocked. All other doors and the luggage compartment will remain locked.
Passive locking will only activate if the key is outside the vehicle. If no key is present externally, two audible error warnings will sound when the door handle button is pressed.
A capacitive plate is molded internally within the exterior door handle; the vehicle exterior body acts as a second capacitive plate. The air between the two acts as an insulator. The control electronics within the door handle evaluate the capacitance of the circuit. When a hand interrupts the space between the handle and the door, the electrical field is altered and thus the capacitance of the capacitor.
The signal is calibrated so as not to
detect false activations (rain or snow, dirt build-up).
Passive Start found in the Range Rover, Range Rover Sport & LR4 is designed to start
the vehicle via the fascia-mounted start/stop button without any mechanical interaction with the key used to open the vehicle. The key is automatically detected as present via cabin-mounted antennas using Low Frequency (LF) and Radio Frequency (RF) signals.
Interesting fact #1:
The key authorization process relies on sufficient battery charge in the key. As these vehicles are not equipped with a docking station to hold the key, charging of the key battery is not possible. When the battery charge falls to an insufficient level there is a message prompt to the driver via the message center. Typical life expectancy for a key battery is approximately two years (depending on usage).
In a situation where the key battery voltage is low, the vehicle can still be started by holding the key against the Immobilizer Antenna Unit (IAU). No battery power is required, as key authorization takes place via an induction process. You can see IAU locations below – LM is the internal designation for the Range Rover, LA is the LR4 & LS is the Range Rover Sport.