Why do the car lights still work when the car is flooded?

[BethanyLee]

This situation occurs because the wiring harness or a certain sensor has short-circuited or been corroded due to water ingress. You can use a computer diagnostic tool to read the fault codes and then check the connectors and sensors. If necessary, you can directly go to a repair shop or a 4S store for inspection and repair. Situations when a car is flooded: 1. Water entering the air filter: If the engine only mixes with water vapor and water enters from the air filter, the problem is not serious. Simply clean the water vapor from the air filter, throttle valve, and cylinder. 2. More water ingress: If the engine takes in more water but does not affect normal driving, although the noise is louder, it may be due to a small amount of water in the oil or gasoline. In this case, you need to change the oil and clean the related engine parts. 3. Engine water ingress: If a significant amount of water enters the engine, rather than just mixing with water, but the car has not been started and the engine is not damaged, you need to drain the water completely, clean the interior thoroughly, reassemble it, and replace the oil. 4. Unable to drive: The worst scenario is when the engine takes in a large amount of water and cannot operate after starting. At this point, the engine's cylinders, connecting rods, pistons, etc., may have deformed, indicating that the engine is already scrapped. You can only replace it with a new engine or scrap the car entirely.

[OLeah]

I've repaired quite a few flood-damaged vehicles, and sometimes the lights still being on can really be puzzling. Possible reasons include the flooding not being too deep, only reaching the tire level, leaving the circuits and battery high and dry. Or the car lights themselves might be well-sealed, like modern LED lights that have waterproof designs, preventing water from entering the core components. Another possibility is that the fuses didn't blow, allowing the current to flow as usual. I remember last year, an SUV was partially submerged after rain, and the owner said the lights were still on because the engine compartment wasn't completely flooded. After flooding, never overlook safety—disconnect the power as soon as possible and tow the vehicle to a professional shop to check the wiring and battery to avoid corrosion and short circuits, which could lead to bigger problems. Regular maintenance of the light seals is also crucial.

[JaylaLynn]

My own car was half submerged in water after a heavy rain, and surprisingly, the headlights were still on. I was quite puzzled at the time, but the mechanic said it might be because the water didn't reach critical areas, such as the headlight position being higher or the battery remaining dry and not short-circuiting. Modern vehicle circuits are protected by insulation layers, so shallow flooding may not directly affect them. However, the dangers of water immersion should not be underestimated. I later noticed some rust inside the headlights and promptly replaced the components to prevent wiring damage. It's recommended to prioritize draining the water by opening the hood in similar situations, avoid forcibly starting the engine, and seek professional repairs to prevent subsequent corrosion-related failures.

[BrielleLynn]

From a design perspective, automotive circuits incorporate waterproofing mechanisms such as sealants and barrier boxes, which may allow lights to remain operational even if the circuit modules aren't fully submerged. For instance, if the connection points between the light assembly and the vehicle body remain dry, electrical current can continue to flow. However, water exposure increases corrosion risks, potentially causing voltage fluctuations or even fire hazards. Remember to inspect fuses and connectors for signs of oxidation.