System Overview
System overview
General
The keyless entry system allows the vehicle to be opened without inserting a key in the lock or pressing a button on the remote key. The system also allows the engine to be started without the remote key in the starting lock. The function is checked by the keyless vehicle module (KVM). The keyless vehicle module (KVM) is located behind the right-hand wheel arch in the luggage compartment. In order to be able to fulfill its tasks, the keyless vehicle module (KVM) is connected to a number of other units such as:
- Antennas in the external door handles on the rear doors
- Antennas in the passenger compartment and luggage compartment
- Antenna in luggage compartment
- Quick lock motor and contact breaker in the lock units in the side doors
- Opening motor in the luggage compartment
- Contact breaker in the luggage compartment's handle
- Contact breaker in the luggage compartment lock unit
- The remote keyless entry (TRX) receiver receives a signal from the remote key
- The switch in the clutch pedal (manual gearboxes) or a signal from the brake pedal switch via the central electronic module (CEM) (automatic transmissions)
- Contact breaker in the starter button
- Lock buttons on the outer door handles
The keyless vehicle module (KVM) is part of the immobilizer system. It communicates with both the central electronic module (CEM) and driver information module (DIM) via the LS-CAN. For further information, see Design and Function, Immobilizer/Start inhibition.
The outer antennas are located in the door handles on the rear doors and in the luggage compartment.
If a door handle is pulled outwards, a contact closes, which alerts the system and activates the antenna in the handle on the rear door on the side where the handle was pulled out. If a valid key is within a 1.5 meter radius of the handle, the relevant door opens and the vehicle unlocks one or more doors. The doors that are unlocked depend on the settings the system has.
The vehicle can also be unlocked if the handle on the luggage compartment lid is affected.
There are additional antennas inside the vehicle which are activated during start attempts. These allow the control module to check for a valid remote key in the vehicle. If there is, the vehicle can be started using the starter button on the dashboard.
There are quick locks in the lock units in the doors. These increase the response time of the system. The quick locks are mechanically connected to the standard lock mechanism. The quick locks can open the door themselves. The time taken from the handle being pulled out to the door opening is reduced. The keyless vehicle module (KVM) checks the remote key, and then opens the first door itself. This saves communication time over the controller area network (CAN) which is used otherwise by the central electronic module (CEM) to check the central locking.
The remote keyless entry (TRX) receives signals transmitted by the remote key. These are sent on to the keyless vehicle module (KVM).
A switch at the brake pedal (vehicles with automatic transmissions) or at the clutch pedal (vehicles with manual gearboxes) informs the system that the vehicle is about to be started. When the switch closes, the keyless vehicle module (KVM) starts scanning for a valid remote key.
The control module can be diagnosed and the diagnostic trouble codes (DTCs) read off.
Note! In certain cases malfunctions may occur in the system when communication between the keyless vehicle module (KVM) and the remote key is interrupted for different reasons. These malfunctions are not due to any electrical faults and do not generate any diagnostic trouble codes (DTCs).
1. If the remote key is held in the hand that is used to press the starter button, remote key identification can fail. This results in a message being shown in the driver information module (DIM). The vehicle will not start either. However, the vehicle will start on another start attempt. The fault does not generate any diagnostic trouble codes (DTCs). The fault is rare.
2. If a button on the remote key is pressed when remote key identification is carried out, reading off will fail. This means that the remote key cannot transmit and receive data at the same time (when a button is pressed on the remote key, the remote key is busy sending "normal" remote key commands). This fault may occur if the remote key is in a pocket or bag and a button has been pressed by mistake.
3. Due to increased ambient radiation, for example, from TV/radio transmitters and mobile phones and meters with remote reading, the signal from the remote key can, in some cases, be interrupted. In many cases this occurs in certain locations, where different outside signals make transmission and reception conditions unfavorable. This affects not only keyless vehicle systems but all types of wireless communication.
4. If the remote key is stored together with a mobile phone in a pocket or purse, it can happen that the mobile phone's signal blocks the remote key's signal to the vehicle. If the remote key's signal to the vehicle is blocked and at the same time the customer tries to open the door by pulling the handle, the feature will not work. The same applies if the remote key's signal is blocked and at the same time the customer tries to unlock the vehicle by pressing the button on the door handle. If these symptoms occur, then no components are to be replaced. Instead, instruct the customer not to store the remote key together with a mobile phone. In order to achieve a flawless function, the remote key and mobile phone must be kept at least 10-15 cm apart.
Signals
The table below summarizes the input signals to and output signals from the keyless vehicle module (KVM). The signal types are divided into directly connected signals, serial communication and controller area network (CAN) communication. The illustration below displays the same information with the Volvo component designations.
