Hyundai Tucson: Auto Lighting Control System

Hyundai Tucson - Fourth generation (NX4) - (2020-2023) - Workshop Manual / Body Electrical System / Auto Lighting Control System


It's a system that uses illumination sensor to automatically turn ON the tail lamp and head lamp based on the change in surrounding environment's illumination condition. It activates when the vehicle enters/ exits tunnel, or when the illumination condition in surrounding environment changes due to rain, snow, or fog. Precautions corresponding to the use of this system are as follows.

  1. Do not add another device on top of this device.
  2. Be sure to switch to manual during poor visibility climate, such as fog, heavy rain, or cloudy weather.
  3. Illumination intensity in an actual vehicle is not always constant, and lamp ON/OFF time may very depending on the climate, season, and surrounding environment.
  4. Use this system only during sunrise and sunset period, and manually control lamp ON/OFF for general conditions.
  5. Error may occur if light block coating that may change interior illumination is applied.

Component Location

  1. Auto light sensor
  2. Head lamps
  3. Lighting switch (Auto)
  4. Tail lamps
  5. IBU (Integrated Body Control Unit)




Check if the auto light control operates like a timing chart shown below.

Tail lamp output and head lamp (Low) output is controlled based on the auto light sensor's input (illumination intensity) when the Auto Light Switch in Multi-Function Switch is turned ON, and the vehicle is in IGN1 or IGN2 ON Mode.

If IGN1 = ON, BCM detects this voltage, and if the voltage exceeds rated voltage, then auto light failure occurs, (below 4V or above 6V)

Failure Occurrence : If auto light failure occurs, the head lamp must be turned ON regardless of sun light level. This is to prevent the head lamp from being turned OFF in case of auto light failure during night time.



  1. Disconnect the negative (-) battery terminal.
  2. Remove the crash pad upper garnish (A).

  1. After removing the crash pad upper garnish, insert hand and push up the photo sensor (A) from the inside to remove it.

  1. Disconnect the auto light sensor connector (A).



  1. Connect the auto light sensor connector and install the auto light sensor.


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