Why don't the hazard lights flash when locking the car?
3 Answers
If the hazard lights don't flash when locking the car, it may be because the car door is not closed tightly, or there is strong signal interference in the parking area causing the remote control to malfunction, or the remote key may be out of battery. If you notice the hazard lights not flashing when locking the car, the owner should check whether the gear is in the P position. If it's not, the hazard lights definitely won't flash when locking. Many cars flash the hazard lights twice after locking, and some cars may also emit a beep sound to remind the owner that the car is locked. This helps prevent the owner from mistakenly thinking the car is locked and leaving, thereby enhancing the car's anti-theft performance. Some cars automatically fold the exterior mirrors and close the windows after locking, which is another safety feature.
I also encountered the issue of the hazard lights not flashing when locking the car last time, which was quite concerning. Later, I took it to the repair shop, and the mechanic said the most common cause is a blown fuse in the body control module, usually located in the fuse box under the steering wheel. However, it might not even be a fault—many new cars now, to save power or due to settings, only flash the turn signal once or show no response at all when locking with the key. My Porsche is like this, and it needs to be adjusted in the central control screen. If an older car suddenly stops flashing, you should pay attention—it could be a problem with the anti-theft system signal receiver or aging wiring causing a short circuit. The most troublesome issue is a faulty body control module, which requires a computer diagnostic test to confirm. Remember to check the manual first to confirm the default settings before troubleshooting.
A couple of days ago, while helping my neighbor check their car, we encountered this exact issue—the hazard lights wouldn't flash when locking the car. We immediately popped the hood to investigate. First, we tested the hazard light relay; pressing the lock button didn't produce the expected 'click' sound. Upon removing it, we found the contacts were indeed burnt out. Even after replacing the relay, the problem persisted. Further inspection of the wiring harness revealed that three wires inside the door sill had been chewed through by rodents. We fixed them ourselves using heat shrink tubing, and everything went back to normal. There's another scenario many people aren't aware of: improperly connecting constant power wires when installing a GPS or dash cam can mess up the BCM module. If the lights suddenly stop flashing after a car wash, it might be due to a short circuit in the door lock switch. These kinds of issues aren't recommended for DIY fixes—it's best to consult a professional and use a diagnostic tool to read the fault codes.
