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I noticed after buying my used clarity from a dealer just now that both key fobs were activating present 2 for seat positions. I looked at the back of both fobs and realized they both say "2"

Is there any way to force one of these as "1" ? I tried setting Driver 1 and locking/unlocking with the fob but it still defaults to 2 for both of them.
 

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2021 PHEV Touring HB, CA
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I noticed after buying my used clarity from a dealer just now that both key fobs were activating present 2 for seat positions. I looked at the back of both fobs and realized they both say "2"

Is there any way to force one of these as "1" ? I tried setting Driver 1 and locking/unlocking with the fob but it still defaults to 2 for both of them.
I'd be going back to the dealer, and ask for a programmed replacement fob 1. For free.

Buying and programming a replacement could set you back hundred$.

I have no idea, because I haven't looked inside of a fob, but I guess it's *possible" that there might be a solder bridge or something similar on the little PC board in the fob that tells it if it's fob 1 or fob 2. Using this method would probably be cheaper for Honda, than having different hardware or software for each fob. It's what I would do.

Good luck!
 

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2018 PHEV Touring Atlanta, GA
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I'd be going back to the dealer, and ask for a programmed replacement fob 1. For free.

Buying and programming a replacement could set you back hundred$.

I have no idea, because I haven't looked inside of a fob, but I guess it's *possible" that there might be a solder bridge or something similar on the little PC board in the fob that tells it if it's fob 1 or fob 2. Using this method would probably be cheaper for Honda, than having different hardware or software for each fob. It's what I would do.

Good luck!
Actually there are three types of fobs, driver 1, driver 2, and "blank" for the Clarity Base. From what I have read people who have had to replace a Touring key fob say you have to get one with the correct fob number if you want to use the seat memory function for two drivers. The fob number seems to be hard coded somehow, either physically as you suggested or else in some type of non-erasable memory. Agree the dealer should replace it with the correct fob at no charge as it costs several hundred dollars to replace it otherwise.
 

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Actually there are three types of fobs, driver 1, driver 2, and "blank" for the Clarity Base. From what I have read people who have had to replace a Touring key fob say you have to get one with the correct fob number if you want to use the seat memory function for two drivers. The fob number seems to be hard coded somehow, either physically as you suggested or else in some type of non-erasable memory. Agree the dealer should replace it with the correct fob at no charge as it costs several hundred dollars to replace it otherwise.
Arrrgh!

I couldn't help myself. Popped them open. I found that the internal PCB/Battery assemblies have different part numbers on the plastic piece that holds the PCB and Battery together (which makes sense). I wasn't willing to pry the PCB off, for fear of damaging it, but the surface I could see looked identical on both. The other side of the PCB is a big unknown, at this point. The Risk:Reward was too high for my comfort.

I'll only go so far for "science". Others may feel differently.
 

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Arrrgh!

I couldn't help myself. Popped them open. I found that the internal PCB/Battery assemblies have different part numbers on the plastic piece that holds the PCB and Battery together (which makes sense). I wasn't willing to pry the PCB off, for fear of damaging it, but the surface I could see looked identical on both. The other side of the PCB is a big unknown, at this point. The Risk:Reward was too high for my comfort.

I'll only go so far for "science". Others may feel differently.
Yeah, you’ve gotta believe there is no difference in the PCBs. There would be no reason to have the extra cost of two different ones. This whole thing with the cost of these fobs is ridiculous though. I’ll bet there’s no more than $10 worth of stuff that goes into making one of those.
 

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Yeah, you’ve gotta believe there is no difference in the PCBs. There would be no reason to have the extra cost of two different ones. This whole thing with the cost of these fobs is ridiculous though. I’ll bet there’s no more than $10 worth of stuff that goes into making one of those.
My guess is that it is controlled by firmware. Aren't the fobs programmed to a particular car? If so, the dealer should also be able to program the driver number.
 

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My guess is that it is controlled by firmware. Aren't the fobs programmed to a particular car? If so, the dealer should also be able to program the driver number.
I doubt that the driver number is programmable like vehicle pairing is. If it was possible, you could have a fob numbered "2" that acts like it's number "1". I would think that would be best avoided.
 

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I doubt that the driver number is programmable like vehicle pairing is. If it was possible, you could have a fob numbered "2" that acts like it's number "1". I would think that would be best avoided.
I would bet that it is programmable but not an accessible programming option by anyone but the manufacturer. If I were designing the key fob that’s the way I would make it work. It’s kind of like the ESN or MEID in mobile telephones. All the PCBs in a certain series of telephones are identical but the ESN or MEID is programmed at the factory and not accessible to be changed by anyone else.
 

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I would bet that it is programmable but not an accessible programming option by anyone but the manufacturer. If I were designing the key fob that’s the way I would make it work. It’s kind of like the ESN or MEID in mobile telephones. All the PCBs in a certain series of telephones are identical but the ESN or MEID is programmed at the factory and not accessible to be changed by anyone else.
I was thinking the same but wondered how it works. The little bit I have read about keyfobs is that they have an EEPROM, which of course is programmable, but I have also read that when a key is programmed the first step is to fully erase the EEPROM, followed by writing the new modified data. So then I wondered if that means the driver setting is on another chip, and written to only at the factory (key fob factory not the car factory). But following your idea maybe they only erase and rewrite part of the EEPROM, leaving the part with driver setting untouched. In which case what I read about first erasing the EEPROM could still be true, or mostly true, just oversimplified because no one else cares about the details except for people like us who stay awake at night wondering about it.
 

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I was thinking the same but wondered how it works. The little bit I have read about keyfobs is that they have an EEPROM, which of course is programmable, but I have also read that when a key is programmed the first step is to fully erase the EEPROM, followed by writing the new modified data. So then I wondered if that means the driver setting is on another chip, and written to only at the factory (key fob factory not the car factory). But following your idea maybe they only erase and rewrite part of the EEPROM, leaving the part with driver setting untouched. In which case what I read about first erasing the EEPROM could still be true, or mostly true, just oversimplified because no one else cares about the details except for people like us who stay awake at night wondering about it.
Yep, I would guess it’s how you have described. Most EEPROMs I have worked with have the ability to erase at the byte level so the “complete erasure” could be erasing all of the pertinent data but leaving the factory programmed bytes alone.
 

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For the Clarity, the fobs come pre-programmed from the factory. The car is then programmed to accept the pre-programmed ID of the fob itself.

We have a "blank" base-model key and a "driver 1" touring key. After the car was programmed, they both operate as "driver 1".

The NXP NCF2952 has an internal 2 kB EEPROM. The documentation of the IC is not public, so I can't say how easy it would be to reprogram the fob.

The NXP chip can use either mask ROM, or "E-ROM" (which it calls flash-like). J-link makes a programmer for the chip (called "2LINK"), which you might need to buy to reprogram the EEPROM. The documentation suggests that if a mask ROM is used, the debug port could be disabled, so programming might not be possible in that case
 
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