Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Fail-Safe Chart
- LED HEADLIGHT SYSTEM
The light control ECU operates in fail-safe mode if an abnormal condition such as those listed below has been detected.
Item Abnormality Detection Condition Return Condition Master Warning Light Multi-information Display Abnormal input voltage (High input voltage) Abnormal power source voltage (more than 17 V) is detected. Normal power source voltage (10 to 16 V) is detected. Flashes CHECK HEADLIGHT SYSTEM Abnormal input voltage (Low input voltage) Abnormal power source voltage (less than 10 V) is detected. Normal power source voltage (10 to 16 V) is detected. Flashes CHECK HEADLIGHT SYSTEM Abnormal output - Open in output side circuit
- Short between output terminal and body ground
Light control switch is turned off. Flashes CHECK HEADLIGHT SYSTEM - AUTOMATIC LIGHT CONTROL SYSTEM
If the main body ECU (multiplex network body ECU) detects a malfunction in the automatic light control sensor, the main body ECU (multiplex network body ECU) performs fail-safe control to prohibit the automatic light control. If the low beam headlights and taillights are on, the lights will remain on until the light control switch is turned off.
- AUTOMATIC HEADLIGHT BEAM LEVEL CONTROL SYSTEM
- The headlight leveling ECU assembly operates in fail-safe mode if an abnormal condition such as those listed below has been detected, and keep the last low beam status.
Item Abnormality Detection Condition Return Condition Warning Indicator Height control sensor power source voltage Abnormal height control sensor power source voltage (4.6 V or less, or 6.25 V or more) is detected. Abnormal voltage is not detected for 5 seconds consecutively Illuminated Height control sensor signal voltage Abnormal height control sensor signal voltage (0.25 V or less, or 4.75 V or more) is detected. High power source voltage Abnormal high IG supply voltage (18.5 V or more) is detected. Voltage of 17.5 V or less is detected Not illuminated Low power source voltage Abnormal low IG supply voltage (9.0 V or less) is detected. Voltage of 9.3 V or more is detected for 0.1 seconds consecutively Not illuminated Height control sensor data out of range Height control sensor data out of range when performing initialization of the headlight leveling ECU assembly Vehicle condition is proper for initialization. Illuminated Variation error Headlight leveling ECU assembly for another destination is installed on the vehicle Headlight leveling ECU assembly for proper destination is installed on the vehicle Illuminated
- The headlight leveling ECU assembly operates in fail-safe mode if an abnormal condition such as those listed below has been detected, and keep the last low beam status.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.