Push Button Start System

The START/STOP button (ignition switch) is used to control the ON, OFF and START ignition modes.

Battery voltage is supplied to the push button ignition switch. When the button is pressed, voltage signals sent out on two separate circuits. One is provided to the BCM and the other is shared by the RFA module and the PCM, indicating a request to change the ignition state. Changing the ignition state from the OFF mode works in conjunction with the PATS. A programmed key is required to change the ignition from OFF to ON. For additional PATS information, Refer to: Passive Anti-Theft System (PATS) - System Operation And Component Description .

With the ignition off and the START/STOP button is pressed, and the RFA module (or the BCM) detects a programmed key, the BCM provides ground to the coil side of the ignition relay and sends an ignition status message over the CAN to other modules to indicate the ignition state change. Unlike a conventional ignition switch system, the push button start system does not have an ACC mode. The BCM only utilizes the OFF, ON and START modes. Each time the ignition state changes, the BCM sends ignition status change to other vehicle modules.

Refer to the following table for information about achieving the various ignition states.

Ignition Entry Condition	Desired Ignition Mode	Action To Take
Off	ON (engine off)	Press the START/STOP button without applying the brake pedal.
Any ignition mode	START	Apply and hold the brake pedal and then press the START/STOP button.
On (engine off)	OFF	Press the START/STOP button.
On (engine running)	OFF	Press and hold the START/STOP button.

The RFA module or the BCM must recognize a programmed key before the ignition state changes from OFF.

OFF

The BCM controls the relays providing voltage to the vehicle electrical systems. When the ignition is in the ON mode, a single press and release of the START/STOP button changes the ignition to the OFF mode. No programmed key is required to change the ignition to the OFF mode when the vehicle is running.

If the vehicle is in motion, a momentary press of the START/STOP button does not shut the vehicle off. If the vehicle is moving, the START/STOP button must be pressed and held for longer than one second to turn the ignition off.

When the ignition switch turns off, the BCM deactivates the ignition relay and communicates the state of the ignition to the other modules by sending a message over the CAN.

The RFA module or the BCM must recognize a programmed key before the ignition state changes out of OFF. When the START/STOP button is pressed with the ignition off, the RFA module (and if no key is detected the BCM) checks for a programmed key as part of the PATS function. If no programmed key is detected, the ignition remains off. For detailed PATS information, Refer to: Passive Anti-Theft System (PATS) - System Operation And Component Description .

When the ignition is in the ON mode, the BCM activates the accessory delay and ignition relays (by providing ground to the coil side of the relays), and sends a message over the CAN to other vehicle modules.

When the vehicle enters ON mode, multiple indicators in the IPC prove out and the IPC displays the gear selection and the vehicle mileage.

START

When the START/STOP button is pressed with the brake pedal applied, the vehicle temporarily goes into the START mode until the vehicle starts (so long as a programmed key is detected within the vehicle).

While the BCM is in the START mode, it activates the ignition relay (by providing ground to the coil side of the relay) and sends a message over the to other vehicle modules. While the engine is cranking, the BCM inhibits the accessory delay relay. After the vehicle starts, the BCM activates the accessory delay relay (by providing ground to the coil side of the relay).

The PCM uses the voltage from push button ignition switch to determine when to activate the starter motor relay. For information on the starting system, Refer to the appropriate Engine System article for the procedure.

Ignition System Message Center Messages

The message center provides instructions for operating the push button ignition system. The message center also displays warnings that indicate a potential concern with the system. These messages pertain to the push button ignition system:

PRESS BRAKE TO START - Momentarily displays when the start/stop switch is pressed without the brake pedal being applied.
NO KEY DETECTED - Displays if a programmed passive key is not detected by the RFA module and the BCM when attempting to change the ignition mode out of OFF. If this message is observed with the passive key located inside the vehicle, Refer to: Passive Anti-Theft System (PATS) - System Operation And Component Description .