Push-Button Start - With Intelligent Access (IA): Notes
Overview
The push-button ignition system uses the following components to achieve the 4 ignition modes (OFF, ACC, RUN and START):
- BCM-B
- BPP
- Intelligent Access (IA) key
- RFA module
- Start/stop switch
- TPM module
To achieve any ignition mode other than OFF, the Intelligent Access (IA) key must be present inside the vehicle. The driver need not perform any actions on or with the Intelligent Access (IA) key to operate the push-button ignition system. It is sufficient that the Intelligent Access (IA) key is located inside the vehicle when the start/stop switch is pressed. Pressing the start/stop switch causes the RFA module to send out a Radio Frequency (RF) signal to the Intelligent Access (IA) key. The Intelligent Access (IA) key responds by transmitting a Radio Frequency (RF) signal to the TPM module. The TPM module then sends a message over a dedicated network to the RFA module that the Intelligent Access (IA) key has responded. The RFA module then sends a message over the MS-CAN to the BCM-B indicating the correct Intelligent Access (IA) key is present. The BCM-B then takes the appropriate action based on the start/stop switch and BPP switch inputs.
Backup Transceiver
If the battery inside the Intelligent Access (IA) key is weak, damaged or if excessive ambient RFI prevents communication between the RFA module and the Intelligent Access (IA) key, the backup transceiver located in the center console storage compartment provides a secondary means for the RFA module to validate the Intelligent Access (IA) key and authorize use of the vehicle. The backup transceiver uses passive Radio Frequency (RF) identification to exchange signals with the Intelligent Access (IA) key, similar to the way a encoded PATS key and transceiver operate. For information on the Intelligent Access (IA) key and backup transceiver, REFER to Passive Anti-Theft System (PATS), With Intelligent Access (IA) , Backup Transceiver.
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 Intelligent Access (IA) key is not detected in the vehicle.
- NO KEY DETECTED - Displays if the Intelligent Access (IA) key is not detected by the RFA module while attempting to start the vehicle, enter ACC or RUN mode. If this message is observed with the Intelligent Access (IA) key located inside the vehicle, REFER to Passive Anti-Theft System (PATS), With Intelligent Access (IA) , No Key Detected Message.
- STARTING SYSTEM FAULT - Displays if the RFA module receives invalid data from the PCM during PATS authentication. If this message is observed, REFER to Passive Anti-Theft System (PATS), With Intelligent Access (IA) , Symptom Chart: PATS.
System Operation
System Diagram
Network Message Chart
| Broadcast Message | Originating Module | Message Purpose |
|---|---|---|
| Passive entry_control code | RFA module | Provides the BCM-B with the Intelligent Access (IA) key data. The data contains information such as if an Intelligent Access (IA) key has been detected, how many were detected and if it is a programmed key. It also contains the RFA module ID which is checked by the BCM-B. |
| Passive entry_fob number | RFA module | Provides the BCM-B with which specific programmed Intelligent Access (IA) key was used. |
| Ignition status (power pack status) | PCM | Provides the BCM-B with the current ignition status of the PCM. |
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 Intelligent Access (IA) key does not have to be in the vehicle to achieve OFF mode. However, the Intelligent Access (IA) 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 module transmits a radio frequency to activate the Intelligent Access (IA) key. If present, the Intelligent Access (IA) key transmits a radio frequency signal to the TPM module. The TPM module sends a message to the RFA module indicating that the Intelligent Access (IA) key is present.
If the Intelligent Access (IA) key is not present, the message center displays NO KEY DETECTED to alert the driver that the Intelligent Access (IA) key is not present.
If the Intelligent Access (IA) 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 Intelligent Access (IA) key being present in the vehicle.
Acc
To enter ACC mode, with the correct Intelligent Access (IA) key inside the vehicle, press and release the start/stop switch one time without pressing the brake pedal. Once the BCM-B receives the message from the RFA module that the correct Intelligent Access (IA) key is present inside the vehicle and the BCM-B has detected the start/stop switch input without the BPP input, the BCM-B activates the RUN/ACC bus and RUN/ACC relay. The BCM-B also sends the ignition mode message to the other modules over the MS-CAN and the HS-CAN.
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 Intelligent Access (IA) key inside the vehicle, press the start/stop switch for a minimum of one second without pressing the brake pedal. Once the BCM-B receives the message from the RFA module that the correct Intelligent Access (IA) key is present inside the vehicle and the BCM-B has detected the start/stop switch input without the BPP input, the BCM-B activates the RUN/ACC bus, the RUN/START bus, the RUN/ACC relay and the RUN/START relay. The BCM-B also sends the ignition mode message to the other modules over the MS-CAN and the HS-CAN.
Once the ignition has entered RUN mode, the indicator in the start/stop switch illuminates and the module controlled indicators in the IPC momentarily illuminate to prove they are functioning correctly. For information on IPC prove out, REFER to Instrumentation, Message Center, and Warning Chimes , Prove-Out.
Start
To enter START mode, with the correct Intelligent Access (IA) key inside the vehicle, press and hold the brake pedal, then press and release the start/stop switch. Once the BCM-B receives the message from the RFA module that the correct Intelligent Access (IA) key is present inside the vehicle and the BCM-B has detected the BPP input with the start/stop switch input, the BCM-B activates the RUN/START bus and the RUN/START relay. The BCM-B also sends the ignition mode message to the other modules over the MS-CAN and the HS-CAN.
The engine can be started from any ignition mode. Once the ignition has entered START mode, the indicator in the start/stop switch illuminates.