Light Control ECU

The light control ECU is an electronic control unit which is necessary for illuminating the metal halide bulb. A light control ECU is located under each headlight unit. This ECU provides the functions listed below:

• Generates the high voltage (approximately 20,000 volts) which is applied to the electrodes of the bulbs to enable the HID headlights to start to illuminate.
• Optimally controls the amperage and voltage in order to quickly provide an optimal amount of light immediately after the bulbs have been turned ON and to enable the bulbs to continue to illuminate in a stable manner.
• A fail-safe function is provided as a countermeasure against the high voltage that is generated in case that a problem occurs in the headlight system.

The light control ECU executes the fail-safe actions listed below in accordance with the item that has been detected.

• Detection of Abnormal Input Voltage -  If the voltage that is input to the light control ECU deviates from the operating voltage (9-16 volts), the ECU stops illuminating the headlights and resumes illuminating the headlights once the voltage reverts to the operating voltage range. However, if the input voltage decreases after the headlights have illuminated, the headlights will remain illuminated until the bulbs are extinguished.
• Detection of Abnormal Output (Open Circuit or Short Circuit) or Flashing Bulb -  If an abnormal condition (open or short circuit) occurs in the voltage that is output by the light control ECU, or if the bulb flashes, the ECU stops illuminating the headlights and will maintain this state until the power is reinstated (by tuning the headlight control switch from OFF to ON).
• Detection of Bulb Open -  If a bulb is not inserted in it's socket, the ECU stops generating high voltage until the bulb is inserted correctly and the power is reinstated (by turning the headlight control switch from OFF to ON or turning the ignition switch from OFF to ON).