Why do the lights turn on when the car is submerged?

[LeKarter]

There may be water ingress in some plugs, causing electrical connections in the car. Below is relevant information about a submerged car: 1. Water level above the exhaust pipe: If the water only covers the exhaust pipe, promptly move the car away. Water in the exhaust pipe will not be sucked back into the engine, and engine stalling is primarily due to water entering the engine's intake system, unrelated to the exhaust pipe being submerged. 2. Water level at half-wheel height: If the water reaches half-wheel height, the car generally won't leak. However, if submerged for a prolonged period with aging seals, leaks may occur. In such cases, drive the car to a 4S shop, remove the interior, clean, and dry it. 3. Water level above half-wheel height: If the water exceeds half-wheel height, the engine may take in water, and the interior may leak. Do not start the engine to avoid damage to the engine or electronic components. Note that insurance will not cover damages caused by ignition in a submerged car.

[RoseMarie]

As someone who frequently tinkers with automotive electrical systems, I suspect your car's lights turned on after flooding because water disrupted the electrical system. Water conducts electricity, and if it enters the doors or hood and contacts exposed wires or the fuse box, it can create a short circuit, accidentally activating the headlights or taillights. Modern car control modules are sensitive, and moisture affecting sensors can also trigger false readings that turn on the lights. I once encountered a similar situation where standing water caused a backup bulb to burn out, which was quite alarming. The key is to immediately cut power to avoid fire risks. After driving through water, don't attempt to start the car—first check that fuses and connectors are dry. Remember, flood damage is severe for cars; it's not just the lights—the engine and control units are at risk of corrosion. It's best to get it repaired promptly and use anti-rust sprays to prevent further damage.

[VonAdalynn]

Last year during a heavy rainstorm, my car was submerged halfway up the wheels. When I parked at midnight, I noticed the headlights were flickering, and my first thought was the danger of a short circuit. Looking back, water intrusion into the wiring is the most common cause of accidental power activation, leading to lights turning on inexplicably. Impurities like mud or salt in the water can enhance conductivity, bridging broken wire circuits. When I popped the hood and saw the wet fuses, I immediately understood the cause. After flooding, it's crucial not to panic—turn off the power and check that the drainage plugs are clear. Older cars with poor sealing are at greater risk. I recommend regular waterproofing tests and being cautious to avoid sensitive areas when washing the undercarriage. Safety comes first—wait for floodwaters to recede before moving, or you risk triggering a chain reaction of failures, even endangering the battery's lifespan.

[AlinaLee]

In the workshop, we've seen many cases of flooded car lights turning on, mostly due to water triggering a short circuit in the electrical system. Simply put, liquid seeps into connectors or switches, bypassing normal control pathways and forcing power through. You can check if the fuse box is soaked, and use a multimeter to detect abnormal voltage for confirmation. The solution isn't complicated: disconnect the power, use a fan to dry internal components, and replace with new waterproof seals. Preventive maintenance is crucial—avoid parking in low-lying areas.