Circuit/System Description

The ignition mode switch has two LEDs that indicate the vehicle power mode. When the vehicle is in the off mode, both LEDs will be off. Pressing the ignition mode switch button once (without the brake pedal applied), the vehicle enters the accessory mode and the amber LED (Accessory) will illuminate. The accessory mode has a 5 min timeout to reduce battery drain. Pressing the ignition mode switch button a s time (without the brake pedal applied), the vehicle enters the run/start mode (without the engine running) and the green LED (Run/Start) will illuminate. Pressing and holding the push button start switch for up to 10 s will place the vehicle in run/start mode (without the vehicle running) and the green LED (Run/Start) will illuminate. With the ignition off (with the brake pedal applied), pressing the ignition mode switch button once, the vehicle will enter run/start mode and the green LED (run/start) will illuminate. This will start the engine. Both LEDs have the voltage supplied from the body control module (BCM). The ignition mode switch sends the ignition mode switch status to the keyless entry control module and to the BCM. The keyless entry control module sends a redundant signal to the BCM with the ignition mode switch status.

The ignition mode switch contains two individual switches that provide redundant switch inputs to both the BCM and the keyless entry control module. The BCM supplies the ignition mode switch a constant B+ signal. The BCM monitors this signal to determine if the switch is released or pressed. When the ignition mode switch is not pressed, voltage on the signal circuit is pulled down through two resistors in the switch. When the ignition mode switch is pressed, voltage on the signal circuit is pulled down through only one resistor, changing the voltage seen at the BCM and indicating that the ignition mode switch is pressed.

The keyless entry control module monitors voltage on the switch in the same manner as the BCM, but monitors the switch located in the ignition mode switch.