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 control. The system also allows the engine to be started without the ignition key in the ignition lock. The function is checked by the keyless vehicle module (KVM). The control module is located under the left-hand front seat. 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 side door handles (C30/C70 front doors, S40/V50 rear doors)
- Antennas in the passenger compartment and luggage compartment
- Antenna in the rear bumper
- Quick lock motors in the lock units in the side doors
- The remote keyless entry (TRX) receiver receives a signal from the 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)
- Key-in switch.
- Switch in door handle and lock button on handle
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 external antennas are located in the door handles (C30/C70 front doors, S40/V50 rear doors) and in the rear bumper.
If a door handle is pulled out, a switch closes. This wakes the system and activates the antennas in the handles on the side on which the handle was pulled out. If there is a valid key within a radius of approximately 1.5 meters of the handles, that door will open and one or more doors will be unlocked. The doors which unlock depend on the system settings. The vehicle can also be unlocked if the boot lid/luggage compartment lid handle 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 key in the vehicle. If there is, the vehicle can be started using the starter switch 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 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 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 key.
There are diagnostics for the system. Any diagnostic trouble codes (DTCs) can be read off using VIDA.
Note! In certain cases malfunctions may occur in the system when communication between the keyless vehicle module (KVM) and the ignition 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 ignition key is held in the hand that is used to turn the starter switch, the ignition 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 if the starter switch is turned to position 0 and another start attempt made. The fault does not generate any diagnostic trouble codes (DTCs). The fault is rare.
2. If a button on the remote control is pressed when the keyless vehicle module (KVM) attempts to read out the identity of the ignition key, reading off will fail. This means that the ignition key cannot transmit and receive data at the same time (when a button is pressed on the remote control, the ignition key is busy sending "normal" remote control commands). This fault may occur if the 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, the signal from the remote control can, in some cases, be interrupted. This is rare but can happen. 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 control is stored together with a mobile phone in a pocket or purse, it can happen that the mobile phone's signal blocks the remote control's signal to the vehicle. If the remote control'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 control'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 this symptom occurs, then no components are to be replaced. Instead, instruct the customer not to store the remote control together with a mobile phone. In order to achieve a flawless function, the remote control 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.
