Hyundai Tucson: Button Engine Start System

Hyundai Tucson - Fourth generation (NX4) - (2020-2023) - Workshop Manual / Body Electrical System / Button Engine Start System


The System offers the following features :

  • Changing the state of engine ignition and power by using the start button.
  • Controlling external relays for ACC / IGN1 / IGN2 terminal switching and STARTER, without use of mechanical ignition switch.
  • Indicating the vehicle status on display by using LED or explicit messages.
  • Immobilizer function by LF transponder communication between fob and fob holder.
  • Interface with Low Speed CAN vehicle communication network.

Button Engine Start System

The Button Start System allows the driver to operate the vehicle by simply pressing a button (called as SSB) instead of using a standard mechanical key.

If the driver presses the SSB while prerequisites on brakes, fob authentication and transmission status are satisfied, the BES System will proceed with the locking/unlocking of the steering column, the control of the terminal, and the cranking of the engine.

The driver can release the SSB as soon as this sequence is initiated. After positive response from immobilizer interrogation, the system will activate the starter motor and communicate with the EMS to check the engine running status for starter release.

The driver will be able to stop the engine by a short push on the SSB if the vehicle is already in standstill. Emergency engine stop will be possible by a long press of the SSB or 3 consecutive presses in case the vehicle is in ENGINE RUNNING.

If the conditions for engine cranking are not satisfied while a push on the SSB is detected and a valid fob authenticated, the system will unlock the steering column and switch the terminals to IGN. Another push on the SSB will be necessary to start the engine.

In case of a vehicle equipped with SMART KEY system, fob authentication will not require any action from the driver. For limp home start or in case of vehicle without SMART KEY. the driver will have to insert the fob into the fob holder.

  1. Control Ignition and engine ON/OFF by Sending signal to IPM.
  2. Display stams by LED Lamp ON/OFF. (Amber or Green)


 Operation for each function of button starting

Electric power ON / Ignition ON The electric power state changes within the range of OFF ->ACC->IGN->OFF by pressing the button without stepping on the brake (Or with stepping on the brake) inside the car with FOB key (However.

 IBU (Integrated Body Control Unit (IBU)

The IBU manages all function related to : -"Start Stop Button (SSB) monitoring", "Immobilizer communication" (with Engine Management System unit for immobilizer release) Authentication server" (Validity of Tran

 Start/Stop Button (SSB)

A single stage push button is used for the driver to operate the vehicle. Pressing this button allows: To activate the power modes ' O f f . 'Accessory', 'Ignition' and 'Start' by switching the corresponding t


 Immobilizer System - Removal

Removal Disconnect the negative (-) battery terminal. Remove the heater control unit. (Refer to Heating,Ventilation And Air Conditioning - "Heater Control Unit") Loosen the mounting bolt,nut,screw and remove the Integrated Body

 GPF Regeneration

This procedures is to forcibly regenerate the GPF with scan tool when the GPF doesn't have been regenerated during driving. For example, if the vehicle has repeated "Low speed driving" or "Short distance driving", the GPF