Push-Button Start - with Intelligent Access (IA)

Push-Button Start - with Intelligent Access (IA)

Overview

The push-button ignition system uses the following components to achieve the 4 ignition modes (OFF, ACC, RUN and START):
- BCM (Body Control Module)
- BPP (Brake Pedal Position)
- IA (Intelligent Access) key
- RFA (Remote Function Actuator) module
- Start/stop switch
- TPM (Tire Pressure Monitor) module

To achieve any ignition mode other than OFF, the IA (Intelligent Access) key must be present inside the vehicle. The driver need not perform any actions on or with the IA (Intelligent Access) key to operate the push-button ignition system. It is sufficient that the IA (Intelligent Access) key is located inside the vehicle when the start/stop switch is pressed. Pressing the start/stop switch causes the RFA (Remote Function Actuator) module to send out a RF (Radio Frequency) signal to the IA (Intelligent Access) key. The IA (Intelligent Access) key responds by transmitting a RF (Radio Frequency) signal to the TPM (Tire Pressure Monitor) module. The TPM (Tire Pressure Monitor) module then sends a message over a dedicated network to the RFA (Remote Function Actuator) module that the IA (Intelligent Access) key has responded. The RFA (Remote Function Actuator) module then sends a message over the MS-CAN (Medium Speed Controller Area Network) to the BCM (Body Control Module) indicating the correct IA (Intelligent Access) key is present. The BCM (Body Control Module) then takes the appropriate action based on the start/stop switch and BPP (Brake Pedal Position) switch inputs.

Backup Transceiver

If the battery inside the IA (Intelligent Access) key is weak, damaged or if excessive ambient RFI (Radio Frequency Interference) prevents communication between the RFA (Remote Function Actuator) module and the IA (Intelligent Access) key, the backup transceiver located in the center console storage compartment provides a secondary means for the RFA (Remote Function Actuator) module to validate the IA (Intelligent Access) key and authorize use of the vehicle. The backup transceiver uses passive RF (Radio Frequency) identification to exchange signals with the IA (Intelligent Access) key, similar to the way a encoded PATS (Passive Anti-Theft System) key and transceiver operate. For information on the IA (Intelligent Access) key and backup transceiver, REFER to Backup Transceiver Passive Anti-Theft System (PATS) - with Intelligent Access (IA).

Push-Button Ignition System Message Center Messages

The message center provides instruction 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.
- ACCESSORY POWER ACTIVE - Displays when the vehicle is in ACC mode.
- SHIFT TO PARK - Displays when the start/stop switch is pressed to shut off the engine with the gear selector lever not in PARK.
- RESTART NOW OR KEY IS NEEDED - Displays when the start/stop switch is pressed to shut the engine off and the IA (Intelligent Access) key is not detected in the vehicle.
- NO KEY DETECTED - Displays if the IA (Intelligent Access) key is not detected by the RFA (Remote Function Actuator) module while attempting to start the vehicle, enter ACC or RUN mode. If this message is observed with the IA (Intelligent Access) key located inside the vehicle, REFER to No Key Detected Message Passive Anti-Theft System (PATS) - with Intelligent Access (IA).
- STARTING SYSTEM FAULT - Displays if the RFA (Remote Function Actuator) module receives invalid data from the PCM (Powertrain Control Module) during PATS (Passive Anti-Theft System) authentication. If this message is observed, REFER to Symptom Chart: Passive Anti-Theft System (PATS) Symptom Chart(s) - with Intelligent Access (IA).

System Operation

System Diagram





Network Message Chart

Module Network Input Messages - BCM (Body Control Module)






OFF

To enter OFF mode, press the start/stop button without pressing the brake pedal while the vehicle is in ACC mode, RUN mode or while the engine is running. The IA (Intelligent Access) key does not have to be in the vehicle to achieve OFF mode. However, the IA (Intelligent Access) key must be present to achieve any other ignition mode.

When the engine is running and any one of the vehicle doors is opened and then closed, the RFA (Remote Function Actuator) module transmits a radio frequency to activate the IA (Intelligent Access) key. If present, the IA (Intelligent Access) key transmits a radio frequency signal to the TPM (Tire Pressure Monitor) module. The TPM (Tire Pressure Monitor) module sends a message to the RFA (Remote Function Actuator) module indicating that the IA (Intelligent Access) key is present.

If the IA (Intelligent Access) key is not present, the message center displays NO KEY DETECTED to alert the driver that the IA (Intelligent Access) key is not present.

If the IA (Intelligent Access) key is not present while attempting to enter OFF mode, the message center displays RESTART NOW OR KEY IS NEEDED. The driver then has up to 20 seconds to restart the vehicle without an IA (Intelligent Access) key being present in the vehicle.

Acc

To enter ACC mode, with the correct IA (Intelligent Access) key inside the vehicle, press and release the start/stop switch one time without pressing the brake pedal. Once the BCM (Body Control Module) receives the message from the RFA (Remote Function Actuator) module that the correct IA (Intelligent Access) key is present inside the vehicle and the BCM (Body Control Module) has detected the start/stop switch input without the BPP (Brake Pedal Position) input, the BCM (Body Control Module) activates the RUN/ACC bus and RUN/ACC relay. The BCM (Body Control Module) also sends the ignition mode message to the other modules over the MS-CAN (Medium Speed Controller Area Network) and the HS-CAN (High Speed Controller Area Network).

Once the ignition has entered ACC mode, the message center displays, PRESS BRAKE TO START and then ACCESSORY POWER ACTIVE.

RUN

To enter RUN mode, with the correct IA (Intelligent Access) key inside the vehicle, press the start/stop switch for a minimum of one second without pressing the brake pedal. Once the BCM (Body Control Module) receives the message from the RFA (Remote Function Actuator) module that the correct IA (Intelligent Access) key is present inside the vehicle and the BCM (Body Control Module) has detected the start/stop switch input without the BPP (Brake Pedal Position) input, the BCM (Body Control Module) activates the RUN/ACC bus, the RUN/START bus, the RUN/ACC relay and the RUN/START relay. The BCM (Body Control Module) also sends the ignition mode message to the other modules over the MS-CAN (Medium Speed Controller Area Network) and the HS-CAN (High Speed Controller Area Network).

Once the ignition has entered RUN mode, the indicator in the start/stop switch illuminates and the module controlled indicators in the IPC (Instrument Panel Cluster) momentarily illuminate to prove they are functioning correctly. For additional information on IPC (Instrument Panel Cluster) prove out, REFER to Prove-Out Instrument Panel Cluster (IPC).

Start

To enter START mode, with the correct IA (Intelligent Access) key inside the vehicle, press and hold the brake pedal, then press and release the start/stop switch. Once the BCM (Body Control Module) receives the message from the RFA (Remote Function Actuator) module that the correct IA (Intelligent Access) key is present inside the vehicle and the BCM (Body Control Module) has detected the BPP (Brake Pedal Position) input with the start/stop switch input, the BCM (Body Control Module) activates the RUN/START bus and the RUN/START relay. The BCM (Body Control Module) also sends the ignition mode message to the other modules over the MS-CAN (Medium Speed Controller Area Network) and the HS-CAN (High Speed Controller Area Network).

The engine can be started from any ignition mode. Once the ignition has entered START mode, the indicator in the start/stop switch illuminates.

Component Description

Body Control Module (BCM)

The BCM (Body Control Module) determines the vehicle ignition mode based on the start/stop switch input, the BPP (Brake Pedal Position) switch input and RFA (Remote Function Actuator) module messages. The BCM (Body Control Module) communicates the ignition mode to the other modules over the MS-CAN (Medium Speed Controller Area Network) and the HS-CAN (High Speed Controller Area Network). The BCM (Body Control Module) monitors the start/stop switch input and the ignition mode outputs, if a fault is detected in the ignition system DTCs (Diagnostic Trouble Codes) are set in the BCM (Body Control Module).

For additional information on the BCM (Body Control Module) functions, REFER to Body Control Module (BCM) Passive Anti-Theft System (PATS) - without Intelligent Access (IA).

Remote Function Actuator (RFA) Module

REFER to Remote Function Actuator (RFA) Passive Anti-Theft System (PATS) - with Intelligent Access (IA).

Brake Pedal Position (BPP) Switch

The BPP (Brake Pedal Position) switch (also known as the stoplamp switch) is a dual contact switch. One set of contacts is normally open and receives voltage at all times. The other set of contacts is normally closed and is connected to ground.

When the normally open contacts close, the voltage is sent to the BCM (Body Control Module), PCM (Powertrain Control Module) and RFA (Remote Function Actuator) module.

When the normally closed contacts open, the ground circuit to the PCM (Powertrain Control Module) is momentarily interrupted.

Start-Stop Switch

The start/stop switch is a momentary contact switch that is hardwired to the RFA (Remote Function Actuator) module, BCM (Body Control Module), and the PCM (Powertrain Control Module). The start/stop switch is connected to both the RFA (Remote Function Actuator) module and BCM (Body Control Module) as a backup in case of a switch or circuit failure. In the event of a switch failure or a circuit failure between the switch and one of the modules, the module that receives the start/stop switch request transmits the request over the MS-CAN (Medium Speed Controller Area Network) to the other module to enable ignition system operation.

The start/stop switch also has 2 LEDs (Light-emitting Diodes), one is used for switch illumination and the other to indicate ignition mode. The ignition mode LED (Light-emitting Diode) only illuminates when the vehicle is in RUN or START mode, it does not illuminate in ACC mode.