What is the reason for the car key flashing red light and not opening the door when pressed?
2 Answers
It may be due to remote control damage, car lock malfunction, or electromagnetic interference nearby. The following are the components of a remote key: 1. Transmitter: Composed of a transmission switch, transmission antenna, integrated circuit, etc., containing an identification code storage circuit and an amplitude modulation circuit, with a button-type lithium battery on the opposite side of the circuit. The transmission frequency uses radio waves, and the transmission switch button sends a signal once per press. 2. Receiver: After the transmitter sends the identification code using shortwave modulation, it is received by the car's shortwave antenna and enters the shortwave high-frequency amplification processor of the receiver's electronic control unit through a distributor for demodulation, and then compared with the demodulator's identification code.
I think when the car key button flashes red but the door won't open, the core issue often lies in a depleted battery. The coin cell battery inside the key loses power over time, weakening the signal transmission so the car can't receive it—resulting in a flashing red light but the door remaining locked. Another possibility is a circuit malfunction in the key itself, such as water damage or physical impact. Interference is also common, like electromagnetic fields from nearby electronic devices disrupting the signal. Try using the spare key first—if it works, simply replace the battery. Don’t forget to check for any metal objects blocking the door. Prevention is straightforward: replace the battery every two years or so, or take it to an auto repair shop for a quick test—it’s low-cost. For safety, avoid forcing the door open or repeatedly pressing the key, as this could lock the system. Seeking professional help is faster.
