Key fob low battery warning after installing new battery

check the 12v health

 

Do you store the key fobs near the vehicle or inside the vehicle? They have little radios and will activate if they sense a vehicle nearby and will drain the battery pretty quick. (Look at your key fob when walking through a parking lot...when you walk by another Toyota a little red light will blink!)
I change out our fob and garage remote batteries yearly...else they seem to go out in the middle of winter at the worst time possible!

 

can't be the 12v then, they never go bad that fast, or lose voltage for any reason.

try disconnecting the neg for a minute to reset everything

 

I keep all of my fobs in a Faraday cage at home. (In this case that translates to an empty pokémon card tin.) A cheap and handy solution for mitigating battery drain.

 

I do the same, When I pull my keys out of my pocket - it goes into a Faraday bag. This also prevent thieves from using a signal booster to access and try to steal the car.
I've been getting an intermittent FOB battery low message on my dash for the last month. Just got around to replacing the battery today. I'll see if that stops the intermittent message. First FOB battery replacement in 4 years.

 

Definitely. I actually started doing it back in Oregon, back then it wasn't kind of sort of maybe technically illegal to steal a car. (Just remember to bring your Crime Committing Kit!)

What brought me to this topic today was trying to get an answer for my friend. He owns a 2020 and asked me
"Did you encounter such behavior of Prius FOB when it constantly shows "low battery, replace" even few days after replacement. And the FOB keeps working for months despite of this warning. It started doing that about 1.5 year ago."

I suggested the Faraday cage and we'll see how that goes.

I also saw people in Subaru forums mentioning perhaps fobs can get "stuck" in Battery Saving Mode when the battery is changed. I'm curious about this hypothesis.

(How to Program a Toyota Key Fob)
How to Program a Toyota Key Fob | Keith Pierson Toyota

 

I have this issue. 2020 Prius. Had it for 2 months or so. Car tells me replace the battery. I did. It’s worse now. It won’t work sometimes. Car still says replace battery. I have to push lock button first many times to get the car to work sometimes. Then push unlock button to unlock doors or lock them.

Yesterday I went to go somewhere. Didn’t work. Door not unlock. After a minute or so of pushing lock and unlock on the key the car finally opened. When where I was going. Hrs later go back to car to come home. Door unlocked. Then car says no key detected. Couldn’t start the car for awhile. Finally worked.

Looked on google for answer. Says if car still says replace battery then reprogram key. To re program it says use the key to put into ignition slot twice. Then do other stuff with the doors. There is no ignition slot so I’m confused.

I can’t go anywhere till this is fixed. Not comfortable.

 

They may have adequate voltage, but how do they load-test. I thought the new batteries should be closer to 3.1-3.2VDC - but I have a calibrated Fluke meter. My job requires annual calibration certificates for my test equipment.

YMMV

 

New 3v batteries should be 3.3v. I have problems with the fob when the battery drops down to 3.0v, and then I replace it with a new battery. I always use a meter to check the voltage of the new battery before I install it in the fob.

 

Anything on my post?

 

get a free 12v load test at many auto parts stores