Why doesn't the car door lock automatically when driving?

[SanJosiah]

The issue of car doors not locking automatically while driving may be caused by failure to meet speed requirements, the auto-lock function being disabled in the vehicle's computer system, or a program malfunction. Automatic locking has speed conditions: Generally above 15 km/h, while some vehicles require speeds above 20 km/h. Automatic door locking scenarios: For example, when the transmission is shifted into D gear, the lock button will automatically engage to prevent accidental door opening. This locking method is used in some Chevrolet and Buick models. In other cases, when the driver applies the brake while driving, the doors will automatically lock - this approach is typically found in domestic or some entry-level vehicle models. There's also a less common locking method where doors automatically lock after the vehicle has been continuously driven for 10 seconds.

[VanMalia]

It's quite common for car doors not to automatically lock, and I often discuss this with car owners. First, check if it's a setting issue—many car models allow you to disable auto-locking in the central control menu, so browse through the settings menu. If the settings are correct, it's likely the door lock actuator is stuck or there's poor wiring contact, especially in older cars. Another possibility is a faulty speed sensor or a glitch in the control module, where the system still thinks the car is stationary even while moving. Also, an improperly closed trunk can affect the entire door lock system. Head to a repair shop to scan for error codes with a diagnostic tool—don’t try removing the door panel yourself, as those plastic clips are fragile!

[FernandoRose]

Failure of the vehicle's automatic locking function is usually caused by a break in the signal chain. The body control module requires a speed signal to trigger the command. If the speed sensor fails, the signal wire is aged or short-circuited, or the module itself malfunctions, the command cannot be transmitted to the door lock actuator. Additionally, check whether the actuator motor is burned out or if the gear set is jammed. Some models are affected by poor contact of the door lock switch, especially the micro switch on the driver's side. It is recommended to first use a diagnostic tool to monitor the speed signal transmission status, then measure the actuator's power supply voltage in sections. If the voltage is abnormal, focus on checking for oxidation issues in the wiring harness connectors from the fuse box to the door panel.

[SadieLee]

Last week, my car had the same issue—it wouldn't lock with a click even at 40 mph. After checking, I found the auto-lock feature was accidentally turned off in the settings. Resetting it via the steering wheel buttons fixed it. If you've confirmed the setting is on and it still doesn't work, it's likely the door lock actuator has failed. My neighbor's German car had this happen due to water seeping in during a car wash, causing the actuator to rust. Another friend experienced a short circuit in the trunk lock mechanism, which disabled the entire car's locking system. First, try manually pressing the central lock button to see if it works—if it does, it's probably a sensor or module issue. Many repair shops now offer free diagnostics; scanning for trouble codes is better than guessing blindly.