Lexus IS250 · Service Manual BODY ELECTRICAL

FAIL-SAFE CHART

System information


FAIL-SAFE

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

    Item
    		 Outline
    Detection of Abnormal Input Voltage
    1. If voltage that is input to headlight beam level control ECU deviates from operating voltage (9 to 16 V), ECU stops illuminating the headlights, and resumes illuminating headlight once the voltage reverts to the operating voltage range
    2. However, if input voltage decreases after headlights have illuminated, headlight will remain illuminated until bulbs are extinguished
    Detection of Abnormal Output (open or short circuit) or Flashing Bulb
    		 If abnormal condition (open or short circuit) occurs in voltage that is output by headlight beam level control ECU, or if bulb flashes, ECU stops illuminating headlights and will maintain this state until power is reinstated (by turning headlight control switch from ON or OFF)
    Detection of Bulb Open
    		 If bulb is not inserted in its socket, ECU stops generating high voltage until bulb is inserted correctly and power is reinstated (by turning headlight control switch from OFF to ON or turning engine switch from off to on (IG))

  2. AFS ECU

    HINT:
    If a malfunction is detected, the headlight swivel ECU assembly (AFS ECU) performs fail-safe operation. Depending on the malfunction, the ECU flashes at 1 Hz intervals or illuminates the AFS OFF indicator in the combination meter assembly.
    Warning massages are also shown on the multi-information display.

    Item
    		 Detection Condition
    		 Leveling motor control
    		 Swivel motor control
    		 Operation restore condition
    		Indicator
    Swivel motor (motor)
    1. Open
    2. Short
    3. Overheat
    		 Continues with the right and left leveling motor positions lowered by 0.8° from the current position
    1. The normal swivel motor returns to the front position
    2. The abnormal swivel motor stops at the current position.
    		 IG ON cycled
    		 Blinks
    Gear malfunction
    1. IG ON cycled
    2. Position change is detected
    Stop position error
    1. IG ON cycled
    2. normal stop position is detected
    Swivel motor (sensor)
    1. Open
    2. Short
    		 Continues
    		 Returns to the front position
    1. IG ON cycled
    2. Normal stop position is detected
    		 Blinks
    Steering angle sensor
    1. Trouble information is received
    2. Communication error
    1. Continues with the right and left leveling motors positions lowered from the current position by 0.8°
    2. Continues after the swivel motor returns to the front position.
    		 Stops at the current position and then returns to the front position.
    1. IG ON cycled
    2. Normal stop position is detected
    		 Blinks
    Speed sensor
    1. Open
    2. Short
    1. Continues using the normal vehicle speed signal that is supplied by the skid control ECU if one sensor is malfunctioning.
    2. Continues determining that the vehicle is stationary if both sensors are malfunctioning
    1. If one sensor is malfunctioning, the swivel motor is controlled using the normal vehicle speed signal that is supplied by the skid control ECU, and the motor returns to the front position.
    2. If both sensors are malfunctioning, the motor returns to the front position.
    		 IG ON cycled
    		 Blinks
    Height control sensor
    1. Open
    2. Short
    3. Pitch angle error
    4. Power source trouble
    		 If the height position is higher than the initial position, the leveling motor is returned to the initial position. If the leveling motor position is lower than its initial position, the leveling motor says at the current position.
    		 Returns to the front position.
    1. IG ON cycled
    2. Normal stop position is detected
    		 Blinks
    Leveling motor
    1. Open
    2. Short
    3. Overheat
    1. The abnormal leveling motor stops at the current position.
    2. The normal leveling motor returns to its initial position if its current position is higher than than initial position.
      The normal leveling motor will stop at the current position if this position is lower than the initial position.
    		 Returns to the front position.
    		 IG ON cycled
    		 Blinks
    BEAN communication
    1. Interruption of headlight signal communication
    2. Interruption of headlight signal from the Windshield Wiper Switch assembly
    3. Interruption of steering sensor zero-point signal
    4. Interruption of front wheel speed signal communication
    		 Continues
    		 Returns to the front position.
    		 Signal is no longer interrupted.
    		 Blinks
    Interruption of AFS OFF switch signal
    		 Illuminates
    1. Interruption of engine speed signal communication
    2. Interruption of vehicle speed communication
    		 Continues
    		 Blinks
    AFS ECU
    		 ECU internal malfunction
    		 Continues
    		 Continues
    		 IG ON cycled
    		 Goes off
    Wheel speed data error
    		 Abnormal front wheel speed signal is received from the skid control ECU
    		 Continues
    		 Returns to the front position.
    		 Normal signal is received
    		 Blinks

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