Description and Operation

Description

System Overview. The system provides the following functions:

• Human-machine interface using a single-stage button to switch terminals and start the engine.
• Control of external relays for switching ACC/IGN1/IGN2 terminals and STARTER, without the use of a mechanical ignition switch.
• Steering column locking by the ESCL device; monitoring of vehicle status to ensure safe activation of the ESCL.
• Vehicle status indication by LEDs or text messages on the display.
• Immobilizer function through LF transponder communication between the key fob and the Start/Stop button.
• Redundant architecture for high system reliability.
• Interface with the vehicle Low Speed CAN communication network.
• Interface with the vehicle LIN communication network, depending on the platform.

RKE and SMART KEY functions are not considered part of this button mechanism. The starting system and are specified in a separate system. Main function of the system

• Steering column lock/unlock by ESCL.
• Switching of ACC/IGN1/IGN2 terminals.
• Control of the BAT line of the STARTER relay (high side) based on communication with the EMS ECU.
• Control of the immobilizer function.
• Control of the BES warning function.

Engine Start/Stop Button System. The push-button start system allows the driver to operate the vehicle by simply pressing a button (called SSB) instead of using a conventional mechanical key. It also controls locking and unlocking of the steering column (called ESCL) without any specific action by the driver. If the driver presses the SSB while the brake pedal is depressed, and key fob authentication and gear position conditions are satisfied, the BES system continues with steering column lock/unlock, terminal control and engine cranking. The driver may release the SSB as soon as this sequence is initiated. After a positive response to the immobilizer request, the system activates the starter motor and communicates with the EMS to check the engine operating status before releasing the starter. The driver can stop the engine with a short press of the SSB if the vehicle is already stopped. Emergency engine stop is possible by pressing and holding the SSB or by pressing it 3 consecutive times when the vehicle is in ENGINE RUN mode. If the engine start conditions are not met when the SSB is pressed, and when a valid key fob is detected and authenticated, the system unlocks the steering column and switches the terminals to IGN. Another press of the SSB is required to start the engine. For a vehicle equipped with the SMART KEY system, key fob authentication does not require any action by the driver. For emergency starting, or for a vehicle without SMART KEY, the driver must press the Start/Stop button.

• Control of ignition and engine start/stop by sending a signal to the IPM.
• Status display using an LED lamp ON/OFF (amber or blue).

Indicator Light On/Off Status with Ignition Key Off

No.	Indicator lamp	Conditions
1	Indicator lamp is on	Door open, tail lamp on, ACC, IG on
2	Indicator lamp illuminated for 30 seconds → lamp off	Door closed, tail lamp off, ignition off
3	Indicator lamp off	Remote LOCK, passive LOCK
4	Tail lamp dimmer rheostat (illumination lamp)

ON/OFF Indicator Status by Ignition Key Position

No.	Ignition conditions	Start button indicator status
1	IG OFF	LED is off
2	IG ACC	LED is yellow
3	IGNITION ON (engine off)	Blue LED on
4	Cranking	Maintain LED status before start
5	Engine is running	LED is off

Wireless Communication. Electromagnetic waves are used to exchange information between the vehicle and the key fob. Two types of RKE keys can supplement the BES system:

• Non-Smart Key RKE
• SMART KEY FOB

At present, the BES system always includes the SMART KEY FOB. The transmitter, receiver and antennas required for communication between the key fob and the vehicle vary depending on the equipment level and the region. RKE and SMART KEY functions are described in separate documents. Refer to Smart Key System for more information on SMART KEY function. The SMART KEY module (SMK) controls all functions related to:

• "Start-stop button (SSB) monitoring",
• "Communication with immobilizer" (with the engine control system unit for immobilizer deactivation),
• ESCL control,
• Authentication server (transponder validity and, in the case of the Smart Key variant, Passive Fob authentication),
• "System consistency check",
• "System diagnostics",
• Control of message display / warning buzzer.

The unit acts as the master throughout the system. When SMART KEY is applied, it controls functions such as Passive Entry, Passive Lock and Passive Authorization, and is integrated for ESCL/terminal switching operations. It collects vehicle status information from other modules (vehicle speed, alarm status, driver door open...), reads inputs (such as SSB, lock button and PARK position switch), controls outputs (such as external and internal antennas), and communicates with other devices via the CAN network as well as single-wire interfaces. It also performs diagnosis and learning of BES system components by the SMK. Transponder

Terminal and Starter Relays. Relays are used to switch the ACC/IGN1/IGN2 terminals. The normally open relays are controlled by the SMK unit and are located either in the passenger compartment or the engine compartment depending on vehicle architecture. Only one relay coil is connected to the terminal outputs of the SMK unit. These relays must include a resistor connected in parallel with the coil to reduce transients during switching. Start/Stop Button (SSB). The single-stage button is used by the driver to operate the vehicle. Pressing this button allows you to:

• To activate the OFF, ACCESSORY, IGNITION and START power modes by switching the corresponding terminals.
• To start the engine
• To stop the engine

The contact is protected by a microswitch, and backlighting is provided to highlight the button marking when required. Two (2) LED indicators are located in the center of the button to display the system status. Another backlight LED is also built into the SSB to illuminate the "Engine Start/Stop" symbols.

Electronic Steering Column Lock (ESCL). The ESCL is required to lock the steering column to prevent unauthorized use of the vehicle. To achieve the required level of functional safety, the ESCL is monitored and controlled by the SMK. This redundant architecture ensures that power is supplied to the ESCL motor only during the lock/unlock operation, and that it is disconnected from the battery and ground lines, to prevent unintended activation while the vehicle is moving. Data exchange between the ESCL and the SMK is performed via an encrypted serial communication interface.

BES System State Diagram. System States in Learning Mode. In learning mode, the BES system can be set to 6 different states, depending on the state of the terminals, the ESCL and the engine:

System Status	Terminal status	ESCL status	Engine Status
1. OFF — locked	OFF	Locked	Stopped
2. OFF — unlocked	OFF	unlocked	Stopped
3. ACC	ACC	unlocked	Stopped
4. IGN	IGN1, IGN2, ACC	unlocked	Stopped
5. START	IGN1, START	unlocked	Cranking
6. IGNITION - Engine	IGN1, IGN2, ACC	unlocked	Run (means "self-sustaining")

Regarding the terminals, the system states described in the table above are the same as in a system based on a mechanical ignition switch. One difference from the mechanical ignition switch system is that the BES system allows a transition from [OFF] to [START] without passing through the [ACC] and [IGN] states. System States in Virgin Mode. The BES system can be set to 5 different states (OFF, LOCKED, not available in virgin mode), depending on the state of the terminals, the ESCL and the engine:

System Status	Terminal status	ESCL status	Engine Status
1. OFF - UNLOCKED	OFF	unlocked	Stopped
2. ACC	ACC	unlocked	Stopped
3. IGN	IGN1, IGN2, ACC	unlocked	Stopped
4. Start	IGN1, START with special activation pattern, refer to chapter 6.2.1 for details.	unlocked	Cranking
5. IGNITION - Engine	IGN1, IGN2, ACC	unlocked	Run (means "self-sustaining")

Regarding the terminals, the system states described in the table above are the same as in a system based on a mechanical ignition switch. One difference from the mechanical ignition switch system is that the BES system allows a transition from [OFF] to [START] without passing through the [ACC] and [IGN] states.