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 to switch the ACC / IGN1 / IGN2 and STARTER terminals without using a mechanical ignition switch.
• Vehicle status indication by LEDs or text messages on the display.
• Immobilizer function by LF transponder communication between the key fob and the key fob holder.
• Redundant architecture for high system reliability.
• Interface with the vehicle Low Speed CAN communication network.
• Interface with the vehicle LIN communication network, depending on platform.

RKE and SMART KEY functions are not considered part of this engine start button system and are described in a separate system. The main function of the system

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

Engine Start Button System. The engine start button system allows the driver to operate the vehicle by simply pressing the button (called SSB) instead of using a conventional mechanical key. If the driver presses the SSB while the brake pedal preconditions are met, key fob authentication and transmission status are completed, the BES system continues with steering column lock/unlock, terminal control and engine start. The driver may release the SSB once this sequence is initiated. After a positive response to the immobilizer check, the system activates the starter and communicates with the EMS to check the engine operating status before cranking. The driver can stop the engine by briefly pressing the SSB if the vehicle is already stationary. An emergency engine stop is possible by pressing and holding the SSB or pressing it 3 consecutive times if the vehicle is in the ENGINE RUNNING state. If the engine start conditions are not met when an SSB press is detected and a valid key fob is authenticated, the system unlocks the steering column and switches the terminals to IGN. Another press of the SSB is required to start the engine. In vehicles equipped with the SMART KEY system, key fob authentication does not require any action from the driver. For a dead battery jump start or in a vehicle without SMART KEY, the driver must insert the key fob into the key fob holder.

• Controls ignition and engine on/off by sending a signal to the IPM and PDM.
• Status indication by the ON/OFF LED lamp (amber or green).

Indicator ON/OFF Status with Ignition Switch OFF

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

Indicator ON/OFF Status According to Ignition Switch 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)	Green LED is 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 FOB. Two types of RKE key may be complementary to the BES system:

• RKE without PEPS
• SMART KEY FOB

Currently, the BES system always includes the SMART KEY FOB. The transmitter, receiver and antennas required for communication between the fob and the vehicle vary depending on functional and regional specifications. RKE and SMART KEY functions are described in separate documents. For more detailed information on SMART KEY, refer to the Smart Key System section. Smart Key

The SMK controls all functions related to:

• "Start-stop button (SSB) monitoring",
• "Immobilizer communication" (with the engine control unit for immobilizer unlocking),
• "Authentication server" (transponder validity and, in the case of the Smart Key option, 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, Passive Entry, Passive Lock and Passive Authorization are integrated for terminal switching operations. It collects vehicle status information from other modules (vehicle speed, alarm status, driver door open, etc.), reads inputs (e.g., SSB, capacitive sensor/lock button, PARK switch position), controls outputs (e.g., exterior and interior antennas), and communicates with other devices via the CAN network as well as LIN interfaces. The SMK is also responsible for diagnosis and study of BES system components. Transponder

Terminal and Starter Relays. Relays are used to switch the ACC/IGN1/IGN2 terminals. These normally open relays are controlled by the PDM and are located either in the passenger compartment or in the engine compartment depending on the vehicle architecture. Only one relay coil is connected to the PWM terminal outputs. 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:

• To activate the OFF, ACC, IGN and START power modes, switch the corresponding terminals.
• To start the engine
• To stop the engine

The contact is secured by a microswitch, and illumination is provided to highlight the button marking whenever required. Two (2) LED indicators are located in the center of the button to display the system status. Another backlight LED is integrated into the SSB to illuminate the "Engine Start/Stop" characters.

System State Diagram. SYSTEM STATES IN LEARNING MODE. In learning mode, the BES system can be set to 6 different states, depending on the terminal status and engine status:

System Status	Terminal status	Engine Status
1. OFF — locked	OFF	Stopped
2. OFF — unlocked	OFF	Stopped
3. ACC	ACC	Stopped
4. IGN	IGN1, IGN2, ACC	Stopped
5. START	IGN1, START	Cranking
6. IGNITION - Engine	IGN1, IGN2, ACC	Run
		(stands for "Self-Contained")

Regarding terminals, the system states described in the table above are the same as in a system based on a mechanical ignition lock. One difference from a mechanical ignition switch-based system is that the BES system allows a special 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, LOCK, unavailable in virgin mode), depending on the terminal status and engine status:

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

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