Push Button Ignition Switch

WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

The push button ignition switch is used to control the ignition mode.

There are 2 circuits the BCM monitors from the ignition switch to change the ignition mode. One circuit is monitored for voltage and the other for a ground signal. When the START/STOP button is pressed, one circuit routes battery voltage to the BCM while a voltage signal from the BCM on the second circuit is routed to ground, indicating a request to change the ignition mode. Changing the ignition mode out of OFF works in conjunction with the PATS. The BCM must recognize a valid programmed key before it changes the ignition mode out of OFF. Refer to: Passive Anti-Theft System (PATS) - System Operation and Component Description .

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

Ignition Entry Condition	Desired Ignition Mode	Action To Take
Off	ON (engine off)	Press the START/STOP button without applying the brake pedal.
Off or on	START	Apply 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.

Ignition Mode LED Indicator

The ignition mode LED indicates the ignition mode of the vehicle. The BCM controls the voltage to the ignition mode LED indicator. Refer to the following table.

Ignition Mode	Ignition Mode LED Indicator
Off	Off
On (engine off)	Flashing
On (engine running)	On

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 at a speed greater than 15 km/h (9 mph), the START/STOP button must be pressed and held for longer than one second (or pressed 3 times within 2 seconds) to turn the ignition off.

When the BCM changes the ignition mode to OFF, it communicates the ignition mode to the other modules by sending an ignition status message over the CAN.

The BCM must recognize a programmed key before it changes the ignition mode out of OFF. When the START/STOP button is pressed when the ignition is off, the BCM checks the vehicle for a valid programmed key as part of the PATS function. If no valid programmed key is detected, the ignition remains off. Refer to: Passive Anti-Theft System (PATS) - System Operation and Component Description .

When the ignition is in the ON mode, the BCM activates the run/start relay to provide voltage to the vehicle electrical systems and communicates the ignition mode to the other modules by sending an ignition status message over the CAN.

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

If the brake pedal is applied when the START/STOP button is pressed, the vehicle temporarily goes into the START mode so long as a valid programmed key is detected within the vehicle.

In addition to activating the run/start relay, the BCM communicates the ignition mode to the other modules by sending an ignition status message over the CAN.

After the ignition has completed the vehicle start sequence, the ignition mode returns to ON and the ignition mode indicator in the ignition switch illuminates steadily.

The engine can be started from any ignition mode.