How to change battery in 2008 key FOB - 2008 Toyota Camry Solara

check battery new doesnt mean free from defects --try reprogramming --try other key fob--test ignition system--

these links should help
Free Keyless Remote Fob Entry programming instructions procedures for all... How to Set Up New Key Remote To Your Car Lost Or Stolen Remote

Dead battery in the Key fob. Or the car battery is dead. There should be a slot on the lower left side of the dash. You slide the fob in buttons up key chain out. They had allot of problems with that system in 2008-2009.

There is a special procedure involved in keying your fob to your car once the battery has been changed. You must lock and open the door with your key. Turn the ignition to "on"(not start) then push the fob's open and close button, then shut off ignition. This procedure is done everything the key battery is changed. Hope this can help you!
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Motorcycle Diagnostic Scanner

This sounds like the key fob is faulty, you will have to take the vehicle to the dealer and have them verify the key fob is faulty, then you can get another key fob programmed for your vehicle, hope this helps

Check this out, not the right year but i doubt that the procedure isn't very different.
How To Replace Jeep Grand Cherokee Key Fob Battery 2014 2015

I have taken a GM key FOB apart before and found a bad soldered connection. If that doesn't work, people sell them on Ebay all the time, look up how to program on the web and reprogram it to match your vehicle.

To take off the battery, first remove the key from the fob, you will see a little **** for the tip of the metal key to slip in (it's only 3mm deep or so). Twist the metal key and you should hear the fob pop. Once it's popped, you can separate the pieces and remove the battery.

New batteries are typically available at Radio Shack. Salesperson at same usually know how to open it.

Hope this helps.

I have the same problem with my 2008 Grand Prix - replaced the batteries in both key fobs - they worked for a few days and quit working. Remote start does not work and both of the cigarette lighter chargers do not work either. I have recieved a "charging system failure" message on the readout screen as well. I have checked with 2 different mechanics and they are not sure what it is. Any help would be appreciated. Thanks!

You can take it back to the dealer, and have them change the battery, or go to Autozone, buy the battery and do it yourself. They can show you how to do it. And which battery it takes. It's not hard to do. Good luck.