Problem programming an used Key Fob

[jnthn98]

Background:
I owned a Mach-E, and bought a genuine OEM Lightning key fob to programmed & used it as a 3rd fob for the Mach-E (successfully).
Traded in the Mach-E for a Lightning and now trying to re-program the extra key fob as the 3rd fob for the Lightning.

From searching through the forum, I found useful information on programming a 3rd key fob for the Lightning. Procedure was straight forward and it looked successful as I got the programming was "successful" message and the hazard light flash. However, when I press the unlock/lock buttons on the extra key fob, it didn't do anything. Thinking that it was a dead fob battery, I switched to a new battery (verified ~3.2V), but it still didn't work. However, the extra key fob was able to start the Lightning when it is in the emergency/programming slot at the bottom of the cupholder.

I can't figure out what the problem is other that there may be a different programming procedure for a used key fob? Has anything run into a similar issue when programming a previously used key fob? TIA!

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[potato]

Double check the frequency. Apparently recent Lightnings use a different frequency than earlier ones. You can use the FCC ID on the original fob (tiny letters you can see when you pull out the physical key) to look it up on fcc.gov.

 

[jnthn98]

Double check the frequency. Apparently recent Lightnings use a different frequency than earlier ones. You can use the FCC ID on the original fob (tiny letters you can see when you pull out the physical key) to look it up on fcc.gov.

Thanks for the tip. Had no idea. Just looked it up on:
https://www.fcc.gov/oet/ea/fccid

My old/extra Lightning fob uses 314.95MHz, while my 2024 Lightning original fob uses ~434MHz. I don't suppose there's a workaround? Not being able to use the old extra key fob is one thing, but I am concern that I just burned through an available key in memory for the Lightning?

Let me explain...for the Mach-E, I heard you can program up to 4 fobs before needing to go to the dealership to erase one. If the Lightning does the same, then my 3rd fob is wasted....programmed in Lightning's memory, but not really working due to incompatible frequency. Can I erase this 3rd fob without FORScan or going to the dealership?

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