How to restart after replacing car key battery?
2 Answers
After replacing the battery, re-pairing is required. The basic components of a remote key consist of the following 2 points: 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 installed 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 short-wave modulation, it is received by the car's short-wave antenna and enters the short-wave high-frequency amplification processor of the receiver's electronic control unit via a distributor for demodulation, where it is compared with the demodulator's identification code.
I've replaced car key batteries several times myself and found that the restart methods vary significantly across different models after a battery change. For regular remote keys, simply pressing the unlock button with a new battery usually activates it. However, some German brands require inserting and removing the key three times to wake it up. With smart keys, after a battery replacement, you typically need to sit in the car, press the brake pedal, and hold the key against the start button for about ten seconds until the dashboard displays a key icon. Last time when I replaced my Mazda key's battery and the unlock didn't respond, I had to research and learned that simultaneously holding the lock and unlock buttons for 10 seconds until the red light flashes was necessary. For complicated cases, consulting the manual is always safest since anti-theft logic differs by brand.
