Description and Operation

Description

System Overview. The system provides the following functions:

• Man/machine interface via 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. The Engine Start Button system allows the driver to operate the vehicle by simply pressing a button (called the SSB) instead of using a standard mechanical key. If the driver presses the SSB while the brake pedal precondition is met, fob authentication and transmission status are verified, 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 inquiry, the system activates the starter and communicates with the EMS to check the engine operating status before starting the starter. 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 times in succession 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 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. For vehicles equipped with SMART KEY, fob authentication requires no action from the driver. For limp-home start or for vehicles without SMART KEY, the driver must insert the fob into the fob holder.

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

Indicator 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 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	White LED is on
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

Operation for Each Start Button Function

1. 1
   Power supply on / ignition on

   A.	The electrical power mode changes through OFF > ACC > IGN > OFF by pressing the button without pressing the brake pedal (or with the brake pedal pressed) inside the vehicle with the FOB key. However, repeat ACC-IGN when the shift lever is not in P. Changing to OFF is not possible.

   B.	START is activated when the button is pressed with the brake pedal depressed and the selector in P/N with the key FOB.

   

2. 2
   Power OFF / ignition OFF

   A.	Ignition OFF is possible when the vehicle is stopped. (Ignition OFF is possible in any ATM lever position.)

   B.	Shift lever is moved to N from P after power OFF in P by pressing the ATM lever release button.

   

3. 3
   How to forcibly turn the ignition off and back on while driving

   A.	This is a method to forcibly stop the engine in case of vehicle lift-down, fuel leakage and emergency (example: accelerator pedal return failure).

   B.

   The engine is turned off and returns to the ACC state when the button is pressed for 2 seconds or more 3 times in a row within 3 seconds while driving. Restart is available within the following 30 seconds regardless of the key FOB, and the power status changes through OFF > ACC > IGN > OFF by pressing the button, without depressing the brake pedal (or with the brake pedal depressed), inside the vehicle with the key FOB. (However, if the shift lever is not in P, ACC-IGN repeats; conversion to OFF is not possible.)

   

4. 4
   0.5-second delay function for brake switch input. Start is possible if the brake pedal is depressed within 0.5 seconds after pressing the start button with the engine off.
5. 5
   Start button indicator (LED) lights depending on the power supply status.

   A.	Power OFF: LED OFF

   B.	ACC power supply status: yellow LED is on

   C.	Power on: blue LED is on

   D.	During start: maintain the LED status from before start

   E.	Initial state: LED off

   

Limp Home Mode

• When brake input is not made (AT specification): transition to START when SSB is pressed for more than 10 seconds in the ACC state.
• In case of communication problems between EMS and CAN (i.e., EMS status cannot be determined): transition to ENGINE RUNNING from START based on RPM input
• In case of a short circuit between the two SSB input lines: power on and off is available by pressing SSB twice within 10 seconds (SSB LIMP HOME PRESS). A buzzer sounds at the first button press. Power cycling is possible, and the buzzer stops when the button is pressed twice within 10 seconds.

Smart Key Unit

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...), reads inputs (such as SSB, capacitive sensor/lock button, PARK switch position), controls outputs (such as external and internal antennas), and communicates with other devices via the CAN network and single-line interfaces. The SMK is also responsible for diagnostics and learning of BES system components. The SMK controls functions related to terminal control by activating external relays for ACC, IGN1 and IGN2. It is also responsible for controlling the STARTER relay. The SMK also controls SSB illumination, as well as the System Status Indicator, which consists of two LEDs of different colors. Fob holder illumination is also controlled by the SMK. The SMK reads inputs (engine fob, vehicle speed, relay contact states), controls outputs (engine relay drivers) and communicates with other devices via CAN. The internal architecture of the SMK is designed so that terminal control is maintained even if one of the two microcontrollers fails, system inconsistency occurs, or CAN communication is interrupted. If one of the two controllers fails, the remaining controller must disable the starter relay. The IGN1 and IGN2 relays must be maintained in the state that was stored before the failure, and the driver must be able to turn off these IGN terminals by pressing the SSB with the EMERGENCY_STOP press sequence. However, engine restart will not be permitted. The state of the ACC relay will depend on the failure type. The main functions of the SMK are:

• Control of terminal relays
• Monitoring of vehicle speed received from the ABS/ESP sensor or ECU.
• Control of SSB LEDs (backlight, clamp status).
• Control of the base station located in the SSB via direct serial interface.
• System consistency monitoring to diagnose SMK failure and switch to the corresponding fail-safe mode.
• Provision of vehicle speed information
• Start-stop button (SSB) monitoring
• Starter power control

Start/Stop Button (SSB). The single-stage button is used by the driver to operate the vehicle. Pressing this button allows the following:

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

The button is secured by a microswitch, and backlighting is provided to highlight the button marking whenever required. Three (3) LED colors are located on the outer ring of the switch assembly. They indicate the system status: OFF (white) / ACC (yellow) / ON (green).

BES (Engine Start Button) System Status Table. 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 (means "self-sustaining")

Regarding the terminals, the system states described in the table above are the same as in the system based on a mechanical ignition lock. One difference from the 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, N/A 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	Cranking
5. IGNITION - Engine	IGN1, IGN2, ACC	Run (means "self-sustaining")

Regarding the terminals, the system states described in the table above are the same as in the system based on a mechanical ignition lock. One difference from the 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.