What is the reason for the failure of headlight height adjustment?
3 Answers
Reasons for the failure of headlight height adjustment: False alarm: If the problem "headlight height adjustment failure" appears, you can let the car stand for more than half an hour and then start it again to see if it has resolved. Headlight control program issue: It is possible that the headlights were not turned off after the car was shut down, which was recorded by the onboard computer or due to other unpredictable issues, causing the headlights to initialize. In this case, you can try reprogramming the headlight module. Whether the headlight control chip is damaged, usually the problem occurs only on one side of the headlight. In this case, you can swap the control chips on the left and right sides for inspection.
Last time I tried fixing my car myself, I ran into an issue where the headlight height couldn't be adjusted, and found there were quite a few potential failure points. The most common one is the height adjustment motor burning out or getting stuck, which is located inside the headlight assembly. Poor wiring connections also frequently occur, especially with loose plugs or wires chewed through by rodents. If the car has automatic headlights, a faulty suspension height sensor can also cause adjustment failure. Additionally, if the control switch button is malfunctioning or doesn't spring back properly, pressing it might not elicit any response. I'd recommend first checking if the fuse is blown. If it's intact, it's best to take it to a repair shop to scan for trouble codes with a diagnostic computer—disassembling the headlight assembly yourself can easily damage the sealant. Definitely don't put off fixing this issue; misaligned headlights are extremely dangerous for night driving, and you might even get fined by traffic police.
A few days ago, my friend's car headlights couldn't be adjusted higher, and it took a long time to fix the issue. For such problems, you need to troubleshoot step by step. First, check if the corresponding fuse in the fuse box has blown. Then, try pressing the adjustment button to listen for any buzzing sound from the motor inside the headlight—if there's sound but the light doesn't move, the adjustment gears might be slipping. For cars with automatic adjustment, pay attention to whether there's a fault reported with the vehicle height sensor, which is prone to mud and water corrosion due to its location on the chassis. Cars with modified HID headlights should also check if the voltage regulator is compatible. Wiring issues are the most troublesome, especially in older cars where aging wires can cause poor connections. If you're handy, you can measure the motor's resistance, but it's still recommended to go directly to a reliable repair shop, as headlights are crucial for nighttime driving safety.
