Mech. key won't work !

a new battery should 3.3 v, but i'm not sure that is the problem. i would take it apart and look everything over, make sure no buttons are stuck and etc.
what do you mean, 'the mechanical key won't start the car'?

 

What kind of battery is it? Some reports here of knock-off batteries creating issues.

 

I think you are supposed to place the fob over the start button so it sees the RFID chip. Not the mechanical key.

 

i've never read that. mine says to hold the fob up to the power button while pushing it. the metal key is only for unlocking the door.

edit; you beat me.

 

The couple of times I've opened the fobs my impression is they didn't make much effort to bullet proof this thing. The fragile circuit board is completely exposed. I think a better design would have an isolated battery bay, that you pop open WITHOUT the whole thing being open and apart.

 

but mendel, that would cost another 17 yen per fob.

 

idk, there are so many fob threads here, gen 2 and 3 are different, you can buy them new and used on ebay, there is something called the 'chicken dance', sometimes a local locksmith can help, it goes on and on.
hopefully, someone else has the answer, all the best!

 

Just for the record, IIRC, when you hold the key fob (not the key) up to the start button, it matters which end of the fob is pointed towards the start button

 

I assumed you would hold the fob with the buttons facing you and the back against the Start button, not using one of the ends.

 

Just saying.....if battery-less fob doesn't work, experiment with key fob orientation.

I have to do tis occasionally.

I keep a mech. key behind the license plate. (The screw that holds the license plate on also holds the mech key.) And a battery-less fob hidden in the car. I can get into and start the car any where any time if needed. (like if my keys get lost on vacation). Once, at home, I couldn't find my regular keys. I fished out the spare, held it up, started the car, went to the store. Handy.