Circuit/System Description

The passive portion of the keyless entry system is considered to be the starting and entry functions that do not require any buttons on the keyless entry transmitter to be pressed. The passive keyless entry antennas are used as short range low frequency (LF) transmitters. As an exterior door handle is pulled on a locked door, the keyless entry antenna transmitter broadcasts a challenge to the keyless entry transmitter that extends approximately 1 meter. If the response from the keyless entry transmitter via radio frequency (RF) is valid, the locked door will be passively unlocked/unlatched and allow the door to be opened. The front doors will open with one pull of the front door handle. The rear doors will unlock with the first pull of the door handle and unlatch with the second pull of the door handle. Similarly, when the start/stop button is pressed, the interior keyless entry antennas sends a challenge to the keyless entry transmitter to determine whether it is inside the vehicle. If the response from the transmitter is valid, the vehicle will start.

When the keyless entry transmitter responds, it sends a radio frequency signal to the external RF antenna located in the back glass. This antenna is connected via coax cable to the remote control door lock receiver (RCDLR). The RCDLR interprets the signal and activates the requested function via serial data message. Poor performance of the system may be due to:

• Insufficient connection of the external RF Antenna to the RCDLR
• Low transmitter battery
• Radio Frequency (RF) interference from aftermarket devices such as 2-way radios, power inverters, cellular phone chargers, computers, etc
• High RF traffic areas, such as gas stations which use pay-at-the-pump RF transponders