System Overview
System overview
General
Note! Vehicles with Blind spot Information System (BLIS) that are not equipped with function for keyless vehicle will still be equipped with Keyless vehicle module (KVM), only the module but not the function. Keyless vehicle module (KVM) is needed to make a communication bus available on Central electronic module (CEM) which normally is used for communication with remote receiver module (LRX). Instead these vehicles are equipped with remote receiver (TRX) connected to Keyless vehicle module (KVM).
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 cargo 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 external door handles on the rear doors
- Antennas in the passenger compartment and cargo compartment
- An antenna in the rear bumper
- The remote keyless entry (TRX) receiver receives a signal from the remote key
- Switch in start button (IAU)
- Lock button and unlock button on tailgate
- Lock and unlock sensors in external door handles
Keyless vehicle module (KVM) is included as part of the system for immobilizer and communicates with Central electronic module (CEM) as well as Driver information module (DIM) via MS-CAN.
For more information, see: Design and Function - Electronic start inhibitor/Start lockout.
The unlock sensors in the door handles sense when a hand is placed on the handle. If a valid remote key is within a radius of approx. 1.5 meters from the handle the relevant door will be unlocked, other doors are then unlocked automatically by the central locking system. Which doors are unlocked depends on the settings for the system. The vehicle can also be unlocked if the unlock button in the tailgate/trunk lid is pressed in.
To speed up the response time for the system, Keyless vehicle module (KVM) sends a CAN-signal directly to relevant control module (Driver door module (DDM) or Passenger door module (PDM)) which unlocks the relevant door. At "normal" unlocking of door via the central locking system the communication runs via Central electronic module (CEM) and then to Driver door module (DDM) and Passenger door module (PDM).
In the vehicle's passenger compartment 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 start button (IAU) on the instrument panel.
The remote keyless entry (TRX) receives signals transmitted by the remote key. These are sent on to the keyless vehicle module (KVM).
Keyless vehicle module (KVM) can be diagnosed and diagnostic trouble codes can be read out.
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 start button (IAU), 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. 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 function 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 fault-free 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.
