I disconnected the battery to charge it. when trying to reconnect it, the alarm goes off. What should I do?

You could try disconnecting battery, leaving overnight and then inserting ignition key and switching on before reconnecting the battery.

It has sometimes worked for me but in reality it seems you probably have an alarm immobiliser fault you need specialist help with.

Stick your key in the ignition and turn to start. That should stop the alarm. However, it sounds like your battery still isn't fully charged. Computer things go haywire when battery voltage is 9.6 volts or less.

I think you have put a power spike through the electrics. Try disconnecting the battery give it a minute and reconnect. The alarm runs through the body processor you can't disconnect it.

Try disconnecting the neg. battery terminal. Open the drivers door and leave it unlocked then reconnect the battery back up.

try resetting alarm lower drivers side window and take out keys,disconnect battery and fully charge it , when you reconnect battery alarm will go off ,put key in drivers side door and turn key all the way open and all the locked 3 times then remove key that should reset alarm.

Either unlock the drivers door with the key, or turn the ignition on and try to start the car. one or the other should disarm the alarm

You factory security alarm needs to be reset.

Insert the key in the drivers door, turn left, then right to disarm and reset it.

Once this is done, charge the battery.

If this does not work, do the reset again, then disconnect the battery and charge it out of the vehicle. Once it is charged reconnect it. You may need to perform the key reset again afterwards.

If this does not work then the system has malfunctioned and either I can explain how to bypass it if you have some level of electric ability or you will have to bring it to a dealer.

best of luck.

it has a seperate alarm ,get the side cutters out and remove it .

yeah. disconnect the battery, put the key in the ignition and turn it to the ON position. leave the driver's side door open, and reconnect the battery. the alarm will chirp a few times while you're putting the battery back on, but this SHOULD work.

you might as well go ahead and take the battery out of the remote for the alarm as well, to make sure its not setting your alarm off as well. you can replace the battery in the remote once the battery is reconnected in the vehicle. the remote might need to be reprogrammed if the alarm goes off again, otherwise its time to go to the toyota dealership!

!!WARNING!! make sure the key isnt in the position to START the vehicle, you just want the key ON. make sure that nothing else in the vehicle is on, and also, be VERY careful when reconnection the battery, as it will spark when it makes its connection. if you have been charging the batter a lot, make sure to give the battery time to cool down, because when car batteries get hot, they emit hydrogen, which is explosive. this IS a risky move, but is the only thing you can do, unless you either install a kill-switch or charge the battery and drive to the dealership while the alarm is going off. sometimes, when you start the vehicle, the alarm will stop, but im assuming this isnt your case.