maybe warning about key fob behavior?

[txj2go]

I was in Utah last week camping in my 2018 JLU, camping meaning sleeping in the back. The first night I locked the doors with the key fob and me inside and went to sleep. The next morning I tried unlocking the doors and the key fob was completely dead. It wouldn't do anything. When I opened the doors manually the alarm went off and beeped until it got tired of beeping, waking up everyone and everything nearby in the wilderness. I couldn't do anything that would turn it off. I got in the drivers seat and couldn't do anything to start the vehicle with a dead key fob. The usual trick of pushing the start button with the fob didn't work. I thought maybe the fob was dead because it was around freezing and batteries tend to do that at low temperatures. I put it in my pants pocket and sat there for about 10 minutes while it warmed up then the Jeep started like normal. I don't know what you are supposed to do with a completely dead key fob but I couldn't get it to do anything. I was careful to keep it in my pocket the rest of the trip and had no more problems. Actually I carried 2 fobs with me, one that I use every day and the spare that I never use. Neither one would work when cold.

From Utah I went to Denver and tried in several normal stores but could not find the correct battery size to fit the fobs. Many stores don't carry that size and the few that normally did carry it happened to be out. So if your dash display at any time thinks your battery is low then immediately start searching for new batteries.

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[DarthAWM]

Strange, I thought the fob had an RFID chip for this exact reason, and pushing the Start/Stop button with it disarmed the alarm/started the vehicle regardless of the fob battery condition.

 

[jaymz]

Strange, I thought the fob had an RFID chip for this exact reason, and pushing the Start/Stop button with it disarmed the alarm/started the vehicle regardless of the fob battery condition.

In my experience, it does, and it will.

 

[NWJeepr]

Should work. ?‍ Did you use the wrong side of the key?

 

[tk1700]

When my FOB battery died I got a FOB not detected when I tried to start the Jeep. Using the RFID end of the FOB against the start button the Jeep started. As a precaution against a dead FOB battery I carry a spare battery in each JL.

 

[txj2go]

Should work. ?‍ Did you use the wrong side of the key?

I'm aware of this procedure. I assure you if you are setting on the side of the trail on a cold Utah morning this procedure will not work. I tried multiple times. It may have something to do with not being able to disengage the alarm system.
Maybe there is a related issue- you lock the vehicle with a functioning fob, come back and cannot unlock it with a non-functioning fob, cannot disengage the alarm even if you try to unlock the door with the metal key, the vehicle won't start when pushing the button with the fob. Maybe if I was able to unlock and disengage the alarm system it would have started with this procedure. This is kind of a catch-22.

 

[txj2go]

When my FOB battery died I got a FOB not detected when I tried to start the Jeep. Using the RFID end of the FOB against the start button the Jeep started. As a precaution against a dead FOB battery I carry a spare battery in each JL.

I'm still trying to find a battery. Once I find one I'll buy a couple of spares and carry one with me. I've had the Jeep for 4 years, maybe that is how long the batteries last. I think my other car, 2007 model, has the original batteries in its fob but its fob just locks/unlocks the doors. It doesn't have any proximity detection.

 

[tk1700]

I bought a pack of 6 from Amazon. Funny thing the one that died is on the 2021JL. Both 2019 FOBs are on the original battery.

 

[NWJeepr]

https://www.amazon.com/Duracell-Lithium-Battery-Medical-Fitness/dp/B0C15XS1PQ/ref=sr_1_5?crid=67YN5LN0OE72&dib=eyJ2IjoiMSJ9.qVCIoTPYH6Pc-kRaWTvLDWIWdveFm7fuPw93PTDYZImX8JXqp1heN5woaO3TXJAn-64fuVikt6K1m-XDtVtYr_m2pU8jyh6kMosGjoXR4O0JM1pfvaL-3qa7ddmpf9GKodbfUYaKmXNgBAEPUjVH9gn5vk7lRP48bTSxwDa6U13g1DmO08kQesYwnEVxvzs5CBvzrcGX1s5GkkDpY64oRYeEdAcHHBxNrN8kRZrlaRM7LM5tp16iUFLGOaG2LhVJ1dmYrdb8-4p5t3Rc69Z05jNOf3dtgURD5irjnabiaNY.phv6M5QbltTtAHPHlr3vsrvdpR-mVTSz4BJG7RadcTQ&dib_tag=se&keywords=cr2450&qid=1712186928&sprefix=cr245,aps,174&sr=8-5

Have it dropped at an Amazon locker if you're still on travels.

 

[Oncorhynchus]

On a very cold winter afternoon, I locked my key fob in the JL but the doors did not unlock. It seemed the sensor was frozen.

 

[alphawolff]

If the key-to-button trick did not work then your key is most likely NOT what caused this issue.

 

[hilljumper]

I was in Utah last week camping in my 2018 JLU, camping meaning sleeping in the back. The first night I locked the doors with the key fob and me inside and went to sleep. The next morning I tried unlocking the doors and the key fob was completely dead. It wouldn't do anything. When I opened the doors manually the alarm went off and beeped until it got tired of beeping, waking up everyone and everything nearby in the wilderness. I couldn't do anything that would turn it off. I got in the drivers seat and couldn't do anything to start the vehicle with a dead key fob. The usual trick of pushing the start button with the fob didn't work. I thought maybe the fob was dead because it was around freezing and batteries tend to do that at low temperatures. I put it in my pants pocket and sat there for about 10 minutes while it warmed up then the Jeep started like normal. I don't know what you are supposed to do with a completely dead key fob but I couldn't get it to do anything. I was careful to keep it in my pocket the rest of the trip and had no more problems. Actually I carried 2 fobs with me, one that I use every day and the spare that I never use. Neither one would work when cold.

From Utah I went to Denver and tried in several normal stores but could not find the correct battery size to fit the fobs. Many stores don't carry that size and the few that normally did carry it happened to be out. So if your dash display at any time thinks your battery is low then immediately start searching for new batteries.

Put your FOB in a good Farady cage or wrap it in aluminum foil if the proximity thing cause the battery to die.

 

[rohdawg]

Strange, I thought the fob had an RFID chip for this exact reason, and pushing the Start/Stop button with it disarmed the alarm/started the vehicle regardless of the fob battery condition.

You’re correct.
It does and it works.

Many stores don't carry that size and the few that normally did carry it happened to be out.

CR2450 pretty easy to come by actually. Any hardware store, pharmacy, home improvement store or electronics store should have them on hand.
Be like @tk1700 and buy a pack of them.

 

[rohdawg]

I'm still trying to find a battery. Once I find one I'll buy a couple of spares and carry one with me.

https://a.co/d/jcuiFPA

 

[txj2go]

You’re correct.
It does and it works.

Somehow I stumbled on a circumstance where it doesn't work.

It would be interesting if someone wanted to replicate my situation and duplicate this behavior- get in the vehicle, lock it with the fob, take the battery out of the fob, see if you can start the vehicle.

If you can stand the noise- get in the vehicle, lock the vehicle with the fob, take the battery out of the fob, open the door, get back in, try to start with the fob.

If none of this works you would have to put the battery back in the fob or have someone standing by outside the vehicle, far away from the vehicle, with another fob.

And BTW for the rest of my trip if I thought I needed to lock the doors I manually locked each door from the inside by pushing on the lock lever. I can't lock the tailgate this way so someone could open the back and tickle my feet.

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