Key fob - low battery - replaced it, no go.

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Joined
Jul 30, 2019
Messages
17
Hello

My 2011 leaf was showing “key fob battery low” icon in the display for the past couple of weeks (winter from here in NZ where I’m from).

So I replaced it with a new CR2025. I made sure it’s facing the right way (flat negative side down, positive side up facing me).

I also measured the battery, it reads 3.35V so it’s definitely healthy. I tried a new battery anyways.

No cigar! The key fob is totally unresponsive.

I put a battery maintainer on my 12V lead acid as well - after having that on overnight, still no go.

Any ideas?

The fob was working the day before yesterday but there’s no response at all from any of the buttons, and it shows key not detected.

I did manage to get into the car with the blade key and start it by holding the key fob right up to the button.

Annoyingly I only got the leaf with the one key fob so now I have no remote locking / start and as you can guess this is super annoying.

Any ideas?
 
Without another (second) key fob there's no way to tell if it's the fob...or the car. You have done everything else you can (made sure both sources have good power).
Don't know what else to do except buy/program another fob.
 
I got the same message a couple of times, so I plugged the car into my maintainer overnight. I haven't checked it again, yet. I have fob batteries if I need to replace that.
 
If the fob was working before you replaced the battery and you were careful to install the new battery with the same orientation, then the fob is probably OK. I have purchased several lithium coin cells (various sizes for various remotes) over the past few years that were defective. Therefore, I suggest you purchase another battery from a different source. A depleted or defective lithium coin ce!l will generally show full voltage when measured with a digital voltmeter without load, but the voltage collapses under load.
 
GerryAZ said:
Therefore, I suggest you purchase another battery from a different source. A depleted or defective lithium coin ce!l will generally show full voltage when measured with a digital voltmeter without load, but the voltage collapses under load.

Agreed. I bought a 4 pack of Duracell CR2025 batteries that simply would not work; no start, no doors, nothing. They worked in other applications but not my key fob.

While you have your fob open carefully check for contact problems. A magnifying glass might help.
 
Alright - there is actually some improvement.

I'm finding that after replacing the battery, the buttons to lock/unlock do not work, however I can lock/unlock the car by pressing the buttons on the trunk lid / driver door. I can also start the car by pressing button (no need to hold it up to the button).

But the buttons to lock/unlock still don't work.

I went to a local computer shop and got a pair of Panasonic 2025s (genuine ones) and put one of those in. No improvement - can lock/unlock the doors by pressing the button ON the door itself, can start the car with push button, but car does not respond to the button presses of the key fob.

So maybe the circuitry that runs the button pressing portion of the fob has died?
 
KeepTheCoalInTheHole said:
Alright - there is actually some improvement.

I'm finding that after replacing the battery, the buttons to lock/unlock do not work, however I can lock/unlock the car by pressing the buttons on the trunk lid / driver door. I can also start the car by pressing button (no need to hold it up to the button).

But the buttons to lock/unlock still don't work.

I went to a local computer shop and got a pair of Panasonic 2025s (genuine ones) and put one of those in. No improvement - can lock/unlock the doors by pressing the button ON the door itself, can start the car with push button, but car does not respond to the button presses of the key fob.

So maybe the circuitry that runs the button pressing portion of the fob has died?
Possibly, but those symptoms are also indicative of a weak key fob battery. Check/clean the battery connectors carefully and try another new battery. Also, it might be good to check/clean the contacts on the circuit board that are parts of the button switches. Pressing the fob button to lock/unlock activates the higher power transmitter in the fob so it takes more current from the fob battery than just transmitting the security code to allow the buttons in the door handles and the car on/off button to function.
 
Alright - good news. I changed nothing but the key fob works now - buttons and everything.

It definitely wasn’t working when I tested it immediately after swapping the battery, but let it sit for a couple hours then had to go to dinner - works perfectly.
 
As I wrote on another post regarding key fob batteries, you might want to try replacing the 2025 with a 2035. Fits exactly, but has more capacity, so lasts much longer.
 
Now that your fob has a new lease on life, I'd think hard about acquiring a second fob. I purchased a '19 SL plus last year which came with only 1 fob. I took my own advice.
 
Excellent advice! I made sure I got two fob's and the code tag when I bought mine from the seller. Stapled the tag to the new title in my name.
These newer "fob" cars aren't like the cars of old, where you could have a locksmith make a key for a few bucks.
 
As I wrote on another post regarding key fob batteries, you might want to try replacing the 2025 with a 2035. Fits exactly, but has more capacity, so lasts much longer.
You might mean 2032. A 2035 might be too tall. The 2032 is a tighter fit than the recommended 2025 but you can still get the cover snapped on. If you're using a 2035 then ignore me. My suspicions are that it's a bit too tall.
 
Of course I meant a 2032. I'm not sure there even is such a thing as a 2035. See what happens when you get old? Thanks for catching this, everyone!
 
Both my fobs went bad a few months ago. I'll try replacing the coin cells again. Fingers crossed.

After cozying up the fob to the start button, the car starts, then says "key not detected"

Original fobs, both ten years old. Both behave the same. Fresh batteries didn't help either one.
 
Smart Things Hub quickly drained both my Nissan key fobs?

My key ring was left on a table, very close to a Smart Things (Internet of Things) hub and the fob soon went dead. A Toyota fob on the same key ring was unaffected.

My spare Nissan fob was stored in a camper 300 feet away from the Smart Things hub, far out of range. After bringing it to the same table near the hub, it very soon went dead also. I replaced the battery but a week later when I tried to drive the car, the fob with the fresh battery was dead again.

One of the two fobs hasn't been anywhere near the Leaf for 3 months, yet its battery was completely drained down to 0.3 volts.

Yesterday I installed fresh batteries measuring 3.3 volts and both fobs work perfectly.

Note, the Smart Things hub is paired with a Smart Things key fob, which it interrogates often to determine its status as either "Present" or "Not Present." The Smart Things key fob is a transponder, and the Nissan fobs are also transponders. Although the Nissan fobs may use a different radio frequency and a different coding, it might be possible the constant pinging from the hub is keeping the Nissan fobs awake all day long and draining their batteries. The Nissan fobs could even be responding to the pings (transmitting).
 
Interesting.
I did a survey and listed over 90 WiFi, Bluetooth, infrared, radio, IOT connected devices in my home. Remember there are two devices for many signals, remotes for TVs, fans, etc. Most are not active at any given time, but many are in active 'listening' mode. The 2 cars and 4 fobs count for 6 and the cars also have radios, WiFi, Bluetooth for your phone app and also SiriusXM and emergency satellite radio.
Smart Things lists 14 TVs, phones, tablets, watches, appliances, etc. Not the fobs but that doesn't mean they aren't responding to stray signals.
We don't seem to have any issues with our LEAF key fobs but we do with my wife's Hyundai Palisade key fob going dead.
I rarely drive it, keep my Palisade key fob in a
metal cabinet by the back door. Hers is typically in her purse in the main part of the house.
Or maybe she just has a bad fob. Maybe trade fobs to see if it makes a difference.
Cheers!
 
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