On Mar 1, 2013, at 8:37 PM, Ken Mandelberg <km@...
> One of my key fobs for my 2001 Prius has stopped working. I checked the battery in it and it still shows the 3 volts its rated at.The other key fob (which hadn't been used for a long time) still works.
> This happened immediately after the 12 volt aux battery in the Prius was replaced by the dealer.
> Is there any chance that replacing the aux battery somehow got one of the key fobs out of sync?
Yes. But the dealer started the problem and the dealer should fix what they broke. But its not the key fob, its the car.
Is not the fob which is cut to match the car's locks (as is the case with physical keys) but it is the car's ECU which makes a copy of the fob's signature to accept. This signature should be kept in nonvolatile memory in the car's ECU. But perhaps something failed?
There is a procedure for reintroducing key fobs to the car's ECU. Believe it has been posted at a number of sites online. But you shouldn't have to mess with it. You paid the dealer a premium price for new battery and installation. The reason the dealer charges a premium is to cover for situations such as this. Its easier to bond fob and car together with the Toyota diagnostic computer. Without, there is a complex sequence of key-in, key-out, brake, door lock, unlock. repeat.
Be sure to take all your fobs to the dealer because if what I'm guessing is true then the car has forgotten everything.
David Kelly N4HHE, dkelly@...
Whom computers would destroy, they must first drive mad.