Replaced Key Battery, Now It Doesn't Work
 

2014 base model FR-S with standard key. Original battery approaching 10 years old, door/trunk lock function (using the buttons on the key) was starting to work intermittently. Replaced battery (2016) with a new one, now NONE of the key functions work.
Looked at a bunch of YouTube videos that claim that the key has to be re-connected to the car by inserting/removing key 4 times and then leaving it inserted in the ignition switch, then opening & closing the door 6 times. The security system light does go out when the key is inserted into the ignition switch, but still can't lock/unlock the doors or open the trunk with the buttons on the key.
There's NOTHING about this in the owner's manual- it just walks you through replacing the battery and says nothing about needing to do anything else.
Am I going to have to take it to the dealership and cough up $100+ for them to spend 30 seconds doing some magical pedal dance or some such?
Thanks

No. Something else is wonky. Does the LED flash? If yes, some component for the transmitter may have fried when it was apart. Static charge? Semiconductors are super vulnerable. Don't need a spark to kill a diode or transistor.

I would check the voltage of the "new" battery with a voltmeter. No guarantee that the battery is good, especially in these specialty sizes.



The car computer memorizes as many as 3 transmitters. Nothing you can do with the key that will change the transmitter characteristics or make the computer "forget" a key.

I second a faulty one due to old battery shelf life.
try a new battery from a different store .


Make shure there is no plastic tab protector stuck on the battery as well..

In my experience with low cells in my fobs, the LEDs always quit flashing whenever the transmitter wasn't working. If the LED flashed, transmitter power was adequate. As the cells neared death, I found I could get the transmitter to work by first holding the button for a couple seconds before trying again.


Pro tip: NO, it will NOT help to push harder on the buttons.

Well, it used to! - :rolleyes:

You're my target audience. :slap:

My hammer says otherwise.

My car beeps and I think something shows on the dash when the fob battery is low... But I could be wrong as I can't remember now.. it's been a few years since I changed the battery.. Oh fuck it, let me get over the 'jet lag' having lost/gained 1hr...

Recording here for posterity, should anyone else have a similar issue: it is entirely possible that a factory sealed package of batteries can have sat in a drawer in your garage for so long that they still show a 3 Volt charge on your Fluke voltmeter, but have lost enough power that they don't produce enough amperage to operate the key functions.
Fresh batteries, folks. Don't be a cheap b@$+@rd like me.

OK, so I'll just keep banging it on the table - :paddle:

Where did we start going wrong?

:sigh:

Are we still talking about key fobs?

Oh, KEY FOBS ....... just put a new battery in them.

:iono: