Hyundai Tucson LM Quiz
Body Electrical System

Description and Operation

In this manual: Body Electrical System
General Information — 1Engine Mechanical System — 44Engine Electrical System — 45Emission Control System — 24Engine Control System/Fuel System — 93Clutch System — 13Manual Transmission — 18Automatic Transmission — 87Four-Wheel Drive (4WD) System — 26Drive Shaft and Axle — 29Suspension System — 35Steering — 20Restraints — 47Brake System — 36Body (Interior and Exterior) — 53Body Electrical System — 202Heating, Ventilation, and Air Conditioning — 58
27steps
~162min
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Description

The SMART KEY system allows the user to access and operate the vehicle in a very convenient way. No traditional key or remote control is required to access the vehicle. The user carries the SMART KEY FOB, which does not require any conscious action by the user (for example, pressing an RKE button). SMART KEY SYSTEM: The system is started by pressing a button on the door handle. After activation, the vehicle sends a request within a limited range. If the SMART KEY FOB receives this request, it automatically sends a response to the vehicle. The system then decides whether to perform a certain action (unlock, lock, etc.) or remain inactive. Similarly, the electric steering column lock (ESCL) is released. Again, communication between the vehicle and the SMART KEY FOB is required before any action is performed. The system offers the following functions:
  • Passive Unlock via Driver and Passenger Door
  • Passive Lock via Driver and Passenger Door
  • Passive Start
  • Passive Trunk Access via Trunk Lid Switch
  • Passive Lock via Tailgate
  • A maximum of 2 fobs can be processed by the system
  • Immobilizer backup antenna driver is integrated in the SSB for TP authentication (i.e., in idle mode)
  • Communication with Engine Management System
  • Communication with SRX
  • LF-RF Communication
  1. Passive Unlock. The system allows the user to access (unlock) the vehicle without performing any action with the SMART KEY fob. This feature may differ depending on the platform as follows:
    A. Pressing the Button on the Door Handle
  2. Passive Lock. The system allows the user to lock the vehicle by pressing the button on the door handle with the SMART KEY fob.
  3. Start Button The system allows the user to release the ESCL and switch power modes (Off, Accessory, Ignition), as well as to start and stop the engine without any action with the ELECTRONIC KEY FOB. See the specifications of the push-button engine start system.
  4. LIMP HOME Mode. In addition, the system provides a so-called "limp home" mode, in which the user can operate all vehicle functions by pressing the key against the SSB.
Smart Key ECU (SMK ECU) The SMK ECU controls all functions related to "Passive Unlock", "Passive Lock" and "Passive Engine Start Authorization". It reads inputs (door handle button, Start Stop Button (SSB), PARK position switch), controls outputs (such as external and internal antennas), and communicates via CAN as well as a single-wire interface to other vehicle devices. To communicate with the SMART KEY FOB, the SMK ECU generates a request (challenge) as an encoded and modulated 125 (or 134.2) kHz signal on the inductive antenna outputs and receives the SMART KEY FOB response via an external RF receiver. The main functional blocks of the SMK ECU are:
  • Power Supply
  • Flash Memory Microcontroller
  • Single-Wire Interface to SRX
  • Single-Wire Interface to EMS
  • Input Stage
  • LF Antenna Amplifier/Driver
  • CAN Communication with BCM
The LF antenna amplifier/driver generates a 125 (or 134.2) kHz sine carrier signal, which is distributed to the various antennas. SMART KEY FOB System supports up to 2 SMART KEY FOBs. Main functions of the SMART KEY FOB:
  • Passive Function: receives the LF call and automatically sends an RF response.
  • Classic RKE function by means of up to 4 buttons.
  • Transponder operation in case of battery discharge or communication failure.
Antennas
  1. Low-frequency transmitting antennas: Inductive antennas in and on the vehicle are used to convert the current supplied by the SMART KEY ECU antenna driver into a 125 (or 134.2) kHz magnetic field, which is the carrier for the SMART KEY test. Three antennas cover the exterior of the vehicle: two antennas in the door handles (DR and PS) cover the area around the doors; one antenna in the rear bumper covers the area around the luggage compartment or liftgate. Up to three antennas cover the vehicle interior and the luggage compartment or liftgate area: two in the cabin and one in the liftgate or luggage compartment.
  2. Bidirectional Immobilizer Antenna (for Limp Home): The backup immobilizer antenna is used to send and receive data: it radiates a magnetic field (125 - 135 kHz call) and receives changes in field strength (transponder response).
  3. External Receiver. The SMART KEY FOB response is received through an external RF receiver, which is connected to the SMK ECU via a serial communication line. The SMK ECU has a connector pin for the serial communication line.
Door handle The front door handles of both doors (driver/passenger door) are equipped with LF transmitting antennas for emitting 125 (or 134.2) kHz. The front door handles are also equipped with a push button. The push button on the door handle serves as a trigger indicating the user's intention to unlock or lock the vehicle. The buttons are installed on the front doors, built into the door handles. Another button is installed on the trunk lid or tailgate.

Operation

Passive Functions The system allows the user to access the vehicle without performing any action (such as pressing an RKE button) using the SMART KEY FOB. It is sufficient for a valid SMART KEY FOB to be within a specified and limited range relative to the vehicle. Thus, the system is capable of detecting and authenticating the SMART KEY FOB within the ranges shown below.

Operating Range

The SMART KEY FOB receives and interprets the call sent from the vehicle through the exterior antennas in free space within a minimum radius of 0.7 m around the exterior antennas built into the door handle; refer to the illustration below. Trunk or tailgate access range is also minimum 0.7 m from the antenna location. The SMART KEY FOB receives and interprets the call sent from the vehicle through the exterior antennas in free space within a minimum radius of 0.7 m around the exterior antennas built into the door handle; refer to the illustration below. Passive Entry (Passive Unlock) Pressing one of the buttons on the door handles when all doors are locked indicates the operator's intention to access the vehicle and thus activates the system to unlock. Passive Lock (Exit) Pressing one of the buttons on the door handles when one of the following conditions is met:
  • At least one door is open and the two-step timer is not running, or
  • The two-step timer is running and one of the buttons other than the front left one is activated.
indicates the operator's intention to lock the vehicle and thus activates the locking system. Passive Trunk/Tailgate Open Pressing the trunk/tailgate switch when the trunk/tailgate is closed indicates the operator's intention to open the trunk/tailgate and thus activates the system. The SMK ECU then sends an LF call to the SMART KEY FOB through the exterior antenna in the bumper. The SMART KEY FOB responds with an RF response. If the received response matches the expected response, the SMK ECU sends a "Trunk/Tailgate Open" message over the CAN network. Passive Trunk Warning (Sedan Only) Whenever the trunk is closed, the SMK ECU uses an appropriate search strategy to avoid the trunk buzzer warning when the FOB is outside the vehicle. The SMK then searches for the SMART KEY FOB inside the trunk compartment. If a valid SMART KEY FOB is detected in the trunk, the SMK ECU activates the SMK external buzzer (TBD) to inform the user that the trunk has been closed with the FOB inside. The SMK sends a trunk reopen command to the BCM if the trunk reopen bit (BK) is set. A "valid" SMART KEY FOB means any SMART KEY FOB belonging to the vehicle, even if it is DEACTIVATED.
  • A blind spot in the trunk, similar to any RF interference, may result in no trunk warning. Due to the antenna penetrating the bumper into the trunk area, the lid may open without the ID device being outside.
  • A blind spot in the trunk, similar to any RF interference, may result in no trunk warning.
SMART KEY Reminder 1
  1. Preconditions: All terminals OFF, at least one door open, and lock status not locked. Checked by the SMK periodically every 100 ms while CAN/LIN is active.
  2. Event: Status of at least 1 door handle changed from unlocked to locked.
  3. SMK Actions:
    A. IF the FOB is not active, the SMK searches for FOBs inside the vehicle cabin. Use the same LF strategy as for the ID OUT warning (registration only, no authentication).
    B. IF the FOB is ACTIVE, the SMK searches for a valid TP.
    If no FOB or TP is found, no action is required. If any valid FOB or valid TP is detected, the SMK unlocks the vehicle by sending a CAN key unlock message with the FOB count. If any valid FOB is detected, the SMK unlocks the vehicle by sending a CAN/LIN key reminder unlock message with the FOB number.
  4. Preconditions: All terminals OFF, any door (including trunk) open, and no FOB-IN and lock status (periodically checked by the SMK every 100 ms while CAN/LIN is active).
  5. Vehicle action: Closing the last door or trunk with the handles locked or while locking is in progress.
  6. SMK actions: 500 ms after closing, if all doors are locked, then:
    A. IF the FOB is not active, the SMK searches for FOBs inside the vehicle cabin. Use the same LF strategy as for the ID OUT warning (registration only, no authentication).
    B. IF the FOB is ACTIVE, the SMK searches for a valid TP.
    If no FOB is found, no action is required. If any valid FOB or valid TP is found, the SMK sends a CAN unlock command and activates the additional buzzer warning. If a valid FOB is found, the SMK sends a CAN/LIN unlock command and activates the additional buzzer warning.
  7. If the final state is ACC or IGN, all doors are closed, and the user initiates SMK locking, the search starts outside the vehicle from the trigger side.
  8. If no valid FOB is found, no action is required, but if a valid FOB is found, the buzzer warning must be activated.
  9. If "b_LiftgateOption == On" and "b_Liftgate Lock Unlock Option == On", the lock warning includes the liftgate as a door and the liftgate unlock button as the door unlock switch.
  10. If the terminal state is OFF and not all doors are closed, and the user initiates SMK locking, the search starts outside the vehicle from the trigger side.
  11. If no valid FOB is found, no action is required, but if a valid FOB is found, the buzzer warning must be activated.
  12. If "b_LiftgateOption == On" and "b_Liftgate Lock Unlock Option == On", the lock warning includes the liftgate as a door and the liftgate unlock button as the door unlock switch.
  13. If the terminal state is OFF, ATWS is considered disarmed, all doors are closed, and the user activates SMK locking, the search starts inside the vehicle cabin.
  14. If a valid FOB is not found, the SMK locking search is started, but if a valid FOB is found, the buzzer warning must sound.
  15. If "b_LiftgateOption == On" and "b_Liftgate Lock Unlock Option == On", the lock warning includes the liftgate as a door and the liftgate unlock button as the door unlock switch.
  16. If the final state is ACC or IGN and vehicle speed is less than 3 km/h, a periodic search (every 3 s) is performed inside the vehicle to confirm that a valid FOB is still in the vehicle.
  17. If a valid FOB is not found, the warning is triggered, but if a valid FOB is found, no action is triggered.
SMART KEY Reminder 2 SMART KEY Door Lock Warning Door Lock Warning 1 Door Lock Warning 2 Door Lock Warning 3 Smart Key Indicator Warning Fail-Safe Functions (Limp Home Backup) If the SMART KEY FOB battery is discharged or transmission fails, the following functions are available:
  • Unlocking/locking doors or trunk (or rear door depending on vehicle equipment): with mechanical key
User Information Functions

ID OUT Warning

  1. Preconditions:
    A. (ACC or IGN1) & (any door open or trunk open)
  2. Event: Last open door closed
  3. SMK action: SMK searches for the SMART KEY FOB inside the cabin.
    A. If a valid SMART KEY FOB is not found, the SMK activates the external buzzer and sends an ID OUT warning via CAN (external buzzer warning and internal buzzer).
    B. If a door is opened and closed again during ignition on/off while a valid FOB is inside, the SMK re-enables authentication and stops the warning. If the terminal is in ACC mode, the SMK must turn on the immobilizer lamp.
If there is an LF fault (LF overheating or LF antenna failure), the system behaves the same as when no FOB is found.
FOB Battery Low Voltage Detection To determine the FOB battery condition, a battery voltage measurement and low voltage detection strategy is implemented in the FOB. Battery voltage measurement will be performed when a FOB button is pressed or an LF measurement command is received. Learning Description This chapter describes the learning procedure for the SMK, ESCL and FOB. A diagnostic tool connection is required to learn the SMK, ESCL and FOB. LEARNING MODE In any mode, the learning process is controlled by the SMK. Before starting the learning service, the Fob-In signal must be active and the vehicle's secret code (called the PIN code) must be known. LEARNING MODE This mode is used by dealers to replace the SMK and/or ESCL and/or key set, or to register additional keys for an existing system. This means the system has already been learned with a specific PIN code. The PIN code is fixed for the life of the vehicle, so the same PIN code must be used in this mode. Otherwise, learning will fail. LEARNING MODE Procedure Description (Step by Step) Purpose: Key learning procedure at the service station Initial Condition:
  • SMK replacement: SMK is not learned, and ESCL and SMART FOB are already learned with the same PIN code.
  • ESCL replacement: ESCL is not learned, and SMK and SMART FOB are already programmed with the same PIN code.
  • Learning additional or new keys: SMK and ESCL are already learned with the same PIN code.
Start After Replacement (Initial Start) Starting is possible after replacing the new SMART KEY FOB, FOB or ESCL.
  • This is for starting from the virgin state
  • All related parts in initial state (Smart Key, ESCL ECM)
  • ESCL is always unlocked on a virgin unit
  • Depress the brake pedal in P or N range
  • Press the start button once with the virgin smart key.

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A quick Hyundai Tucson LM quiz: every answer comes with an explanation and a link to the manual page.