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Remote Keyless Entry (TRX) Receiver

Fig 1: Identifying Remote Keyless Entry (TRX) Receiver
GLL162968Courtesy of VOLVO CARS CORPORATION

Remote keyless entry (TRX) is mounted in the middle of the headlining above the rear seat. The receiver receives signals from the remote key and forwards them to the keyless vehicle module (KVM).

The remote keyless entry (TRX) receiver has a logic which enables it to check that a correct message is received. All communication is decrypted in the keyless vehicle module (KVM).

The remote keyless entry (TRX) receiver has three different modes: 

In normal mode, the receiver waits for a signal from the remote key when a button is pressed.

If the keyless vehicle module (KVM) receives an indication from the door handle that someone is trying to open the vehicle using keyless entry, the keyless vehicle module (KVM) transmits a signal to the receiver to switch to passive mode for a pre-determined period of time. After this time, the receiver reverts to normal mode. The difference between these two modes is the way in which the receiver communicates with the remote key.

When a remote control key has been approved and is used to start the vehicle, or if there is a key in the starter module, the central electronic module (CEM) ignores all messages from the remote keyless entry (TRX) receiver. This prevents the central locking system from unlocking if a button on the remote control key is unintentionally pressed in.

The remote keyless entry (TRX) receiver is powered by the central electronic module (CEM) and grounded in the body.