Why are the rear tail lights of the car always on?
The constant illumination of the car's rear taillights is mostly due to improper operation or a faulty brake switch. First, check the handbrake and the light switch. If it doesn't work, then investigate the wiring or the control module.
Check if you didn't close the door properly
If the handbrake is not fully released: The taillights may keep lighting up as a reminder for some vehicle models.
If the steering wheel light switch is misadjusted: After the engine is turned off, moving the steering wheel to one side will activate the parking warning light. Reset it to the middle position.
If the headlight switch is in the automatic position: In the automatic headlight mode, the taillights may remain illuminated due to ambient light.
Common fault points
Brake light switch stuck: The internal contacts of the switch are stuck or the spring is broken, and the circuit is still conducting even without pressing the brake. This is the most common issue.
Taillight circuit short circuit: The wiring harness is aged and damaged, causing the live wire and the ground wire to accidentally touch.
Lamp filament sticking: The filament has melted and remains in a conductive state.
How to check by yourself
Press and release the brake pedal several times and observe if the taillights change. Check if the handbrake has been completely released, if the light switch has been reset, and if it's ineffective, it is recommended to go to a professional repair shop to use a diagnostic tool to detect the fault codes of the control module.
Minor fog usually disappears on its own. Severe water ingress requires checking the seals or sending it for repair. Choose different handling methods based on the situation.
How to deal with minor fog by yourself
Turn on the taillights to dry them out: Keep the taillights on for 1 to 1.5 hours to use the heat from the bulb to evaporate the water vapor.
Let it dry naturally: Park the car in a dry and ventilated place or in a sunny area for more than one day. When the humidity is below 50%, the fog will gradually disperse.
Remove the dust cover: Remove the taillight dust cover to allow water vapor to escape faster, but the process is slower.
How to handle severe water ingress
Check the lamp by disassembling: If there are tools available, you can disassemble the lamp cover to dry it and check if there are any damages or cracks on the surface of the taillight.
Replace the sealing parts: Check if the rear lamp seal ring is aged or cracked. If necessary, replace the rear cover sealing strip and ventilation pipe.
Send it to a professional repair shop: If there are many water droplets or water dripping, it is recommended to go to a 4S store or repair shop for maintenance.
Never use a hair dryer to heat or pour water to shake it evenly. High temperature can cause plastic to contract unevenly and easily crack.
The core function of the car's rear taillights is to inform the following vehicle "where I am" and "what I am going to do". Through different colored light signals, the taillights convey the vehicle's position, width, and dynamic intentions, thereby ensuring driving safety in night and low visibility conditions.
What is the use of the constantly illuminated lights
Position lights (outline lights) usually emit red light and remain illuminated at night or in rainy and foggy conditions, outlining the vehicle's shape and width, allowing the following vehicles to accurately determine your position and size, avoiding misjudgment of the distance.
How to alert during braking
The brake light is brighter than the position light and turns on immediately when the brake is pressed, emitting a strong red light to convey a clear signal to the following vehicle "I am decelerating or stopping", especially in congested sections, it can effectively prevent rear-end collisions.
How to indicate during steering and reversing
The turn signal uses amber flashing to indicate the direction of turning or lane change. The reversing light emits white light to illuminate the rear road and also reminds "the vehicle is about to move backward". The fog light enhances visibility in heavy fog and rainstorms.
These lights combined form the visual communication language between the vehicle and the traffic participants behind. Regular checks to ensure normal operation are the basic responsibility of every car owner.
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