Why don't the button lights work after replacing the car key battery?

[OEli]

The reasons why the button lights don't work after replacing the car key battery are: 1. The replaced battery model does not match the original key battery model; 2. There was an installation problem when replacing the key battery, and reversing the positive and negative poles will also cause it to be unusable. The method for replacing the car key battery is: 1. Use a small flat-head screwdriver to gently pry open the seams around the key shell; 2. Open the shell; 3. Use a small flat-head screwdriver to pry out the battery and replace it with a new one. The methods for using the key are: 1. After the vehicle is turned off, long press the close button on the remote key to close the windows; 2. Press the red horn-shaped button on the key to locate the vehicle position based on the honking sound; 3. Press the trunk button to automatically open the trunk.

[DelLane]

After replacing the car key battery, the button light doesn't come on. I've encountered this several times, and it's actually no big deal, but you need to check step by step. The most common issue is installing the battery backward, with the positive and negative terminals reversed, resulting in no power to the circuit. Last time I did it myself, I almost messed up—the new battery looked identical, and I didn't notice the small markings before snapping it in. Secondly, the new battery itself might be of poor quality, especially if it's cheap or has been in storage for a long time, as the voltage may be insufficient, making the replacement pointless. Additionally, the contacts inside the key might be too dirty, covered in dust, or oxidized, preventing the battery from making proper contact when installed. I recommend reopening the key, cleaning the contacts, and double-checking the battery orientation. If you're unsure, try swapping in a fresh battery or ask a knowledgeable friend to test the voltage. If the light still doesn't work, there might be an internal short circuit or a burnt component—don't force a repair in this case; it's safer to take it to a professional shop. Remember to handle everything gently to avoid damaging the spring contacts.

[Nigel]

After replacing the battery, if the key light doesn't turn on, the issue often lies in circuit details. I made this mistake when I first learned about cars—after replacing the battery, the light wouldn't work because the contact points weren't properly connected, and the copper strip was loose, failing to press the battery tightly. If the new battery's voltage is insufficient, such as below 3 volts, the light also won't illuminate. Additionally, the internal switch might be stuck or worn, or components could be damaged due to static electricity or moisture. I recommend opening the key and using a multimeter to measure the battery's output voltage; it should normally be between 2.7 and 3.3 volts. If the voltage is fine, check the button switch's condition and gently clean the interior with an alcohol swab. Before replacing the battery, ensure the environment is dry to avoid static interference with the chip. If all steps are correct but the light still doesn't work, the key's motherboard might be faulty—attempting DIY repairs carries risks, so it's better to have a technician inspect it. Remember not to use hard tools to pry open the key, as this could damage the wiring.

[McBraxton]

After replacing the battery, the button light on the key doesn't work. The reason is simple - mainly incorrect installation or a faulty battery. Open the key to check the battery orientation; the negative terminal must align with the negative mark. If installed backward, no current flows, so the light naturally won't turn on. It could also be a poor-quality new battery - try another one of the same model. Check for dust on the internal contacts and clean them to ensure a secure connection. If everything seems fine, the key itself might be damaged, such as a worn-out button switch. Immediately visit a 4S shop or repair center for a professional checkup - don't delay. Otherwise, you might face trouble when unable to unlock the car while driving.

[Luca]

After replacing the battery, the light doesn't turn on. I often help friends analyze this issue. The most common cause is installing the battery backwards, or the new battery having unstable performance. Rusty or dirty contacts can also interrupt power. Loose internal springs with insufficient pressure may fail to contact the battery. Environmental factors like moisture causing short circuits require extra attention. Excessive force during installation might damage circuit board components. When reinstalling, gently press the battery to confirm firmness and clean contacts with a soft cloth. Test the new battery's voltage - replace if low. If troubleshooting doesn't work, the internal switch or chip might be damaged, requiring professional repair. Address promptly to avoid affecting driving convenience.