Key Fob not working after changing the battery

Forum for Infiniti M35 and M45, and Nissan Fuga owners.
barneshouse
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Key Fob not working after changing the battery

Postby barneshouse » Wed Oct 14, 2015 7:21 am

I changed the battery to one of my key fobs for my M35, but after changing the battery it is still not working. It has been dead for a while, but I don't know if that has anything to do with it, but I am not sure why it isn't working. I tried 2 different brand new batteries. Any information would be greatly appreciated


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Rogue One
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Re: Key Fob not working after changing the battery

Postby Rogue One » Wed Oct 14, 2015 7:25 am

Take it to the service department at either your local Nissan or Infiniti dealership. They have a device that can check your fob.

barneshouse
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Key Fob not working

Postby barneshouse » Wed Oct 14, 2015 8:20 am

I changed the battery in one of my intelligent keys last night and it is not working. I bought 2 brand new batteries and neither of them work. My other key works. I have the battery in the correct way, so I am not sure what the issue could be. It works when I stick it in the slot in the car but not when I try to unlock or lock the car

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Ilya
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Re: Key Fob not working

Postby Ilya » Thu Oct 15, 2015 6:34 am

Sounds like, for some crazy reason, by taking the battery out both of your keys lost the programming. According to Google, this can only be done by the dealer or sometimes an advanced locksmith (someone who actually works on newer cars).

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Rogue One
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Re: Key Fob not working after changing the battery

Postby Rogue One » Thu Oct 15, 2015 6:45 am

barneshouse, I'm guessing you forgot you'd already created the first thread an hour before the second one. Threads merged. Just an FYI, if you use the search feature to look for your recent posts, please realize it can take up to 24 hours for it to show in the search results.

midnightclub619
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Re: Key Fob not working after changing the battery

Postby midnightclub619 » Sun Jan 03, 2021 1:55 pm

I know this is an old thread but i see that there wasn't much movement any reply that they were able to get this to work.

I'm am now experiencing this issue. My old battery is starting to die as my car is not starting to recognize the key fob all the time. For now, it works flawlessly, car starts with no issues and all the doors function with the key fob. My issue is when I insert a fresh CR2025 battery, which is what is in the key fob right now. Now, my car is not recognizing the key fob at all. It won't start the car, the dash remains dark when I push on the brake pedal and push the start button. I can't lock or unlock my doors. But, when I do insert the key fob into the slot (forgot the name) the car beeps and I am able to start the car as normal.

I wasn't able to find a remedy for this issue on the threads on here. Would anyone have any info for a fix?

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VStar650CL
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Re: Key Fob not working after changing the battery

Postby VStar650CL » Sun Jan 03, 2021 3:23 pm

If you're sure the battery isn't accidentally inserted upside-down, make sure the metal "contact fingers" are making contact with the top of the battery. The reason the key slot works is because there are three different radio systems inside the fob, a low-frequency FM for the buttons, a GHz frequency FM for inside the car, and a passive RFID system for the key slot. The RFID is there for exactly the reason you're using it, emergencies. Because it's passive, it will usually function even if the fob has been drowned.

midnightclub619
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Re: Key Fob not working after changing the battery

Postby midnightclub619 » Thu Jan 07, 2021 3:09 pm

So I worked on the tabs inside the key fob to make better contact and still no response with the new battery. Not sure what step to take next.

midnightclub619
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Re: Key Fob not working after changing the battery

Postby midnightclub619 » Thu Jan 07, 2021 3:10 pm

Does anyone know if we can we reprogram these remotes ourselves?

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VStar650CL
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Re: Key Fob not working after changing the battery

Postby VStar650CL » Thu Jan 07, 2021 4:23 pm

midnightclub619 wrote:
Thu Jan 07, 2021 3:10 pm
Does anyone know if we can we reprogram these remotes ourselves?
Nope, not on an I-key fob. Takes a dealer or a locksmith.

midnightclub619
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Re: Key Fob not working after changing the battery

Postby midnightclub619 » Thu Jan 07, 2021 4:49 pm

VStar650CL wrote:
Thu Jan 07, 2021 4:23 pm
midnightclub619 wrote:
Thu Jan 07, 2021 3:10 pm
Does anyone know if we can we reprogram these remotes ourselves?
Nope, not on an I-key fob. Takes a dealer or a locksmith.
Thanks for the info. I do have the spare I can use so I guess I'll use that and take the spare to the dealership in the near future.

midnightclub619
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Re: Key Fob not working after changing the battery

Postby midnightclub619 » Mon Jan 11, 2021 12:27 pm

So I did some more testing of my issue and got a resolution. I went to use my spare key fob on my car and nothing worked, doors wouldn't open so I couldn't even get in to see if i could start the car. So I got a "new" battery and put it in my spare key fob, and nothing. Still couldn't open my doors. So this led me to believe it was the "new" battery as the issue. I then got another "new" CR2025 and put it in the spare key fob and still no response. So I opened a brand new package of CR2032's and popped it in the spare key fob and BAM! doors opened and I was able to start the car with the CR2032 in my spare key fob. So then I put a new CR2032 in my original key fob and BAM, everything works as expected. So I figured my "new" CR2025's were the issue, they were not new but old (i don't know how old but probably really old) bc I tested them with my battery tester and they had no juice left.

I know there is a difference in just the size between the CR2025's and CR2032's (25mm vs 32mm) but thankfully the CR2032 fit in my keyfob and haven't had any issues since. They are both 3v batteries so that wouldn't be an issue if I used them in the key fob. The reason I used CR2032's is just bc I picked up a pack of 12 from Costco that were on sale so I'll just keep using them until I run out.

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VStar650CL
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Re: Key Fob not working after changing the battery

Postby VStar650CL » Mon Jan 11, 2021 12:38 pm

The 2032's just have more amp-hours and last longer, they're fine. Lithiums have funny discharge properties compared to carbons or alkalines, they start out around 3.05V and deliver an almost flat discharge curve until they hit 2.99V. Once they go below that, they die very quickly. So don't assume a lithium is good because it's "near" 3V. For a lithium, it's on life-support at 2.95V and at 2.90V it's doornail-dead.

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DaSerb
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Re: Key Fob not working after changing the battery

Postby DaSerb » Mon Jan 11, 2021 9:57 pm

Had similar issue last week...fob died with 2032 battery inside. I tried two different brand new 2032 batteries and still wouldn't lock or unlock the door. It did however start the car if fob inserted into the slot. Tested both batteries on a different fob which they worked. I also bought 2025 battery for a different vehicle and tried it. It worked flawlessly.

Not sure what is the difference but going back to 2025 worked.

Good Luck

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VStar650CL
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Re: Key Fob not working after changing the battery

Postby VStar650CL » Tue Jan 12, 2021 5:39 am

DaSerb wrote:
Mon Jan 11, 2021 9:57 pm
Not sure what is the difference but going back to 2025 worked.
The 2032's are thicker by 0.7mm and sometimes can distort the contact fingers to the point where they lose contact. That varies from fob to fob. On most fobs a 2032 won't cause issues, but on some it will.

Working in the slot doesn't tell you anything about the battery, because the doghouse uses a separate RFID signal that doesn't need the battery to function. It's the emergency start system, designed to work even if the fob has been drowned. You can actually stick the bare circuit board in the slot, without housing or battery, and the car will start up fine.


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