Engine Start Button

Components and Component Location

Components

[4DR]

[5DR]

Description and Operation

Description

System Overview

The system provides the following functions:

• Changes the ignition and engine power status using the Start/Stop button.

• Control of external relays for switching the ACC / IGN1 / IGN2 terminals and STARTER, without using a mechanical ignition switch.

• Displays the vehicle status on the display using LEDs or explicit messages.

• Immobilizer function through LF transponder communication between the key and the key 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 the platform.

The RKE and SMART KEY functions are not considered part of this push button mechanism. Start system functions are specified in a separate system.

Main system function

• 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 Button

The push button start 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 is applied, and key authentication and transmission status are satisfied, the BES system continues with steering column lock/unlock, terminal control and engine start.

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 and communicates with the EMS to check the engine operating status for starter cranking.

The driver can stop the engine with a short press of the SSB if the vehicle is already stationary. Emergency engine stop is possible by pressing and holding the SSB or pressing it 3 times consecutively when the vehicle is in the ENGINE RUNNING mode.

If the engine start conditions are not met when the SSB is pressed and a valid key is detected and confirmed, 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 authentication requires no action by the driver. For emergency start or for a vehicle without SMART KEY, the driver must insert the key into the key holder.

Note:

1. 1

   This condition is displayed only when it is a common situation for the engine start button.

2. 2

   This is the condition when the certification is valid.

3. 3

   Operation may differ depending on the gear shift lever position.

   • When in P range: OFF → ACC → IGN → OFF → ACC

   • Except when in P range: OFF → ACC → IGN → ACC → IGN

Operation for each push button start function

1. 1

   Power supply on / ignition on

   • The power supply state changes in the order OFF → ACC → IGN → OFF by pressing the button without depressing the brake pedal (or with the brake pedal depressed) inside the vehicle with the FOB key. (However, when the shift lever is not in P, the power switches repeatedly between ACC and IGN. Conversion to OFF is not possible.)

   • The ignition is turned on by pressing the button with the brake pedal depressed when the shift lever is in P/N with the FOB key.

   

2. 2

   Power OFF / ignition OFF

   • Ignition switching OFF is possible when the vehicle is stopped. (The ignition OFF state is possible regardless of the ATM lever position.)

   • The lever can be shifted to N for parking by pressing the ATM lever unlock button after power is turned off in P.

   

3. 3

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

   • This method is used to forcibly turn off the ignition in the event of a fuel leak, vehicle rollover, or emergency situation (for example, when the accelerator pedal is stuck and returns).

   • The engine is turned off and returns to the ACC state when the button is pressed 3 or more times in succession within 3 seconds for 2 seconds or more while driving. Restart is available within the following 30 seconds regardless of the FOB key and power 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 FOB key. (However, if the shift lever is not in P, ACC ↔ IGN is repeated. Conversion to OFF is not possible.)

   

4. 4

   Brake switch input 0.5-second delay function.

   Starting is possible when the brake pedal is depressed within 0.5 seconds after pressing the start button with the engine off.

5. 5

   The start button status indicator (LED) illuminates depending on the electrical power state.

   • Power OFF: LED OFF

   • ACC power supply status: yellow LED is on

   • Power on: green LED illuminated.

   • During starting: the previous ON state of the LED is maintained until cranking.

   • Initial state: LED off

Wireless communication

Radio waves are used to exchange information between the vehicle and the FOB key. Currently, the push-button engine start is used together with the Smart key.

The Smart key function is described separately, so refer to the relevant system contents.

Main functions

• ACC / IGN1 / IGN2 terminal switch

• Starter relay control (communication with EMS ECU)

• Immobilizer function control

• Engine start button system (BES) warning function control

System Block Diagram

Smart Key Unit

The SMK controls all functions related to:

• "Start-stop button (SSB) monitoring",

• Communication with the immobilizer (with the engine control module for immobilizer disabling),

• 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 of the entire system.

When SMART KEY is applied, for example, Passive Entry, Passive Lock and Passive Authorization are integrated into the terminal switching operations.

It collects vehicle status information from other modules (vehicle speed, alarm status, driver door open, etc.), reads inputs (for example, SSB, capacitive sensor/lock button, PARK position switch), controls outputs (for example, external and internal antennas), and communicates with other devices via the CAN network as well as single-wire interfaces.

Diagnostics and learning of BES system components are also performed by the SMK.

The SMK controls functions related to terminal control by activating the external relays for ACC, IGN1 and IGN2. This unit is also responsible for controlling the STARTER relay.

The SMK also controls the SSB backlight and the "system status" indicator, which consists of two LEDs of different colors. The key fob holder backlight is also controlled by the SMK.

The SMK reads inputs (engine key fob, vehicle speed, relay contact status), controls outputs (engine relay output drivers) and communicates with other devices via CAN.

The internal architecture of the SMK is designed so that terminal control is protected even if one of the two microcontrollers fails, a system inconsistency occurs, or CAN network communication is interrupted.

If one of the two controllers fails, the remaining controller must disable the starter relay. The IGN1 and IGN2 terminal relays must be maintained in the state stored before the failure, and the driver must be able to switch these IGN terminals off by pressing the SSB in the EMERGENCY_STOP press sequence. However, engine restart will be prohibited. 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 for diagnosing SMK failure and switching to the appropriate limp home mode.

• Provision of vehicle speed information

• Start-stop button (SSB) monitoring

• Starter power control

Limp home mode

• If there is no brake input signal (AT specification), the ACC mode must switch to START by pressing the SSM for more than 10 seconds.

• In case of communication problems between the EMS and CAN (EMS status).

  The state changes from START to ENGINE RUNNING based on the engine speed input.

• If one of the two SSM input lines is disconnected,

  Power on and off is available by pressing the SSB twice within 10 seconds (SSB LIMP HOME PRESS).

  A buzzer sounds when the button is pressed for the first time.

  The power supply cycle is available, and the buzzer stops when the button is pressed twice within 10 seconds.

Terminal and starter relay

The relay is used to switch the ACC/IGN1/IGN2 terminals. The normally open relay is controlled by the smart key unit.

One relay coil is connected to the output terminal of the smart key unit.

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 secured by a microswitch, and backlighting is provided to highlight the button marking when necessary.

Three (3) LED colors are located on the outer ring of the switch assembly. They indicate the system status.

They are OFF (white) / ACC (yellow) / ON (green).

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 safety integrity, the ESCL is monitored and controlled by the SMK. This redundant architecture ensures that the ESCL motor is powered only during lock/unlock operation and that it is disconnected from the battery and ground lines to prevent unintended operation while the vehicle is in motion.

Data is exchanged between the ESCL and the SMK via an encrypted serial communication interface.

BES System State Diagram

SYSTEM STATES IN TEACH-IN MODE

In teach-in mode, the BES system can be set to 6 different states, depending on the state of the terminals, the ESCL, and the engine:

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

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:

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