The immobilizer system has been incorporated into the remote control door lock receiver (RCDLR). The immobilizer is provided in order to prevent the vehicle operation if the correct key fob is not used in order to start the vehicle. The ignition button is pressed and the keyless entry antenna backup broadcasts a challenge to the key fob. If the challenge is met, the key fob will transmit via radio frequency (RF) to the RCDLR to enable the vehicle to start. This is accomplished by the RCDLR sending a fuel enable message to the engine control module (ECM).

The design of the keyless access with push button start system is to prevent vehicle theft by disabling the engine unless the correct key fob is present when attempting to start the vehicle. The system is similar in concept to the PASS-Key® III System. However, the keyless access with push button start system eliminates the need for a key; the key fob is considered to be the key. The components of the keyless access with push button start system are as follows:

The start button is located at the upper right side of the steering column on the instrument panel. The start button is used to start the vehicle engine, turn OFF the vehicle engine, put the vehicle in ACC mode or put the vehicle in RUN mode.

The start button signals the body control module (BCM) to ground the Run\Crank control relay which will then feed power to the Crank relay in the under hood fuse block. The BCM must also simultaneously send a serial data message to the engine control module (ECM) to ground the starter enable relay to allow power to the starter solenoid and starter motor.

The key fobs are not only used to passively or actively lock and unlock the vehicle, they are also used to enable the vehicles engine to be started. If the remote control door lock receiver (RCDLR) does not receive a valid radio frequency (RF) signal after the fob is challenged by the keyless entry antenna backup, the RCDLR will not send a fuel enable message to the engine control module. A NO FOB DETECTED message will display on the driver information center (DIC).

When any one of the 4 allowable programmed key fobs are challenged by the keyless entry antenna backup, by pressing the start button, they will passively send a RF signal to the RCDLR; the RCDLR will then send a serial data message to the engine control module (ECM) to enable fuel so the vehicle's engine can be started.

The keyless entry antenna backup is located in the glove box area. It has a small pocket next to it where the key fob can be inserted if the key fobs battery is dead, weak or the radio frequency (RF) signal is being jammed.

The purpose of the keyless entry antenna backup is to send a low frequency RF challenge to a programmed key fob, inside the interior of the vehicle, when the start button is pressed. The keyless entry antenna backup is controlled by the remote control door lock receiver (RCDLR).

Important: The remote control door lock receiver (RCDLR) is not on the GM LAN high speed bus, therefore the RCDLR and the engine control module (ECM) must use the body control module (BCM) as a gateway in order to communicate.

The BCM is located in the interior on the passenger side of the vehicle. It can be accessed by pulling back the carpet in the passenger foot area under the glove compartment. The body control module is a multi-function module. The BCM is used in the vehicle theft deterrent system as a gateway for the RCDLR to send a fuel enable message to the ECM. The RCDLR is not on the GM LAN high speed bus. The RCDLR will send a Class 2 message through the BCM as a gateway to the ECM to receive the fuel enable password.

Important: The remote control door lock receiver (RCDLR) is not on the GM LAN high speed bus, therefore the RCDLR and the engine control module (ECM) must use the body control module (BCM) as a gateway in order to communicate.

The RCDLR is a multi-function module located in the upper passenger side of the dash panel. The RCDLR can be accessed by removing the upper dash pad. The keyless entry antenna backup is controlled by the RCDLR, along with three other low frequency antennas used for passive vehicle entry, but not for the immobilizer. The RCDLR will send an AC voltage signal and provide ground to the keyless entry antenna backup when the ignition button is pressed. This will enable the keyless entry antenna backup to send out the low frequency broadcast challenge to a key fob in range. The RCDLR also has an internal radio frequency (RF) antenna to receive the key fobs passively or actively sent signal. The RCDLR is the module responsible for sending the fuel enable serial data message, if all the vehicle theft deterrent requirements are met.

The SECURITY telltale appears on the instrument cluster. If the SECURITY telltale flashes or if the SECURITY telltale lights continuously during the vehicle operation, there is a problem with the immobilizer system and it should be serviced by the dealer. The SECURITY telltale is a dual purpose indicator, and with the ignition OFF, it is controlled by the content theft deterrent system. With the ignition ON it is controlled by the immobilizer system.

Important: The remote control door lock receiver (RCDLR) is not on the GM LAN high speed bus, therefore the RCDLR and the engine control module (ECM) must use the body control module (BCM) as a gateway in order to communicate.

The ECM communicates with the BCM and the RCDLR over the serial data line. When the RCDLR determines a no start condition, it sends a serial data password to the ECM in order to disable the starting system. If the RCDLR receives a valid key fob radio frequency (RF) transmitted frequency, the RCDLR sends a serial data password to the ECM in order to enable the starting system. The ECM then allows the vehicle to start correctly. If the serial data password from the RCDLR to the ECM is not within the Vehicle Security Status Message, the vehicle will not start. If the ECM does not receive the same password from the RCDLR as the last learned one, the vehicle will not start.

The design of the keyless access with push button start system is to prevent theft even if the various theft deterrent parts change. The parts that can no longer be changed without the possibility of going into a tamper mode are:

If you replace the key fobs, the new key fobs must be relearned to the RCDLR, Refer to Transmitter Programming . When replacing a RCDLR, you must relearn the existing key fobs to the new RCDLR; the ECM must also be put in learn mode to learn the new RCDLR password. Refer to Transmitter Programming and Programming Theft Deterrent System Components . When replacing an ECM with a new GM SPO part number, that has not learned a vehicle theft deterrent password from any other vehicle, the ECM will learn the RCDLR vehicle theft deterrent password on the first ignition cycle.