Rick's Free Auto Repair Advice

Flashing security light after battery replacement

Security light flashing after battery replacement

If you have a security light flashing after battery replacement issue, here’s what to do:

Chances are you left the key in the ignition when changing the battery. If so, disconnect the battery cables, remove the key, and then reattach the battery cables. If you still get a security light or horn beep, try starting the vehicle. If that doesn’t work, press the panic button on your remote, then try starting.


What’s happening is that the anti-theft system needs power to read the transponder in your key. However, in order for your key to generate a response, it has to first receive a broadcast from the transmitter located around your lock cylinder. If you’ve left your key in the ignition and then disconnected the battery, the transmitter is trying to receive a signal when it’s still powering up from the new battery. It doesn’t see the proper key, so it set off the flashing security light.


If none of these suggestions work and you still have security light flashing after battery replacement, you’ll have to get the trouble codes scanned. Any time a warning light flashes, there’s a trouble code stored in the computer.


©, 2015 Rick Muscoplat


Posted on by Rick Muscoplat

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