Key fob lock/unlock doesn't always work (not dead batteries)

[johnmayqwerty]

Originally Posted by STIMAN

I know this thread is old, but I wanted to share that I have/had the exact same issue, both keys (even the one that has sat at home and was never used).

I added a folded piece of paper behind the battery to push it harder against the contacts and that seems to have solved the issue.

Thank you wparsons for posting this thread as it helped solve the problem for me.

Same for me.



AND I previously thought it might have to do with car battery voltage AND/OR temperature... because it seemed like there was a correlation. But it was the battery contacts in the key, so definitely try that first.

[Cheeky]

2020 and still useful, thanks wparsons!

I am another case where the key fob just started not responding. It only happened this year's winter, so I was almost sure it was the cold. I also sometimes kept the key in my jacket pocket near my chest, and it would stay warm and work 100% (not only warm up my car, but gotta warm up my keys too LOL). The moment I leave the key elsewhere it would stop working.

Then I found this thread and decided to try... I put a piece of thicker ad paper, cut to size, folded in two to double layer it, placed it underneath the battery area. I had tested it before the paper mod, and it did not work. With paper mod, it immediately worked.

UPDATE: Tried key the next morning.... it worked at first (with a slight delay) starting in the car, but then stopped working 10 mins after I arrived to destination. Took the PCB out of the key, held battery tight while mashing the buttons and nothing worked. Beginning to think it has some sort of RF interference like the other poster said.

[LotsaMiles]

Well, mine stopped working. I replaced the battery in the fob, like I do with all my cars, and it still doesn't work. And my wife's key, that gets used, um, NEVER, doesn't work either. And the batteries are making contact.

It's not the fobs. It's something in the car. And it doesn't matter where it is or where it's parked. Odd that I can find nothing resolving this on the internet.

[ZexelGTR]

Originally Posted by DoomsdayJesus

I know what was likely causing the same problem with my keyless ignition/keyfob.

If you have LED dome lights or aftermarket LEDs that stay on after the doors close, they can bleed a LOT of RF interference across the spectrum. Anyone with aftermarket blinkers or brake lights (the plug in/bulb-replacement variety) listening to an AM radio, especially at night, can attest to that fact.

I had the exact same problem until I realized that I was immediately able to lock the car from a distance as soon as the dome light faded. If I locked the car by touch and the light went out immediately, it worked every time. But basically the LEDs could be jamming your keyfob.

The solution could be to use some RF shielding, something as simple as the anti-static bags electronics come in, as long as they're transparent enough for lights or even with a small hole cut in them. Or you could figure out where to apply some better grounding either to the receiver or the LED bulb ground. I'll try to post some pictures later if I remember.

Just thought I'd chime in to anyone else having problems with their key fob. This was the solve for me.

My 2020 BRZ wouldn't lock either by the touch pad on the door handle or the lock button on the fob itself. Even after a dealership visit, I couldn't figure it out until I started suspecting my LED license plate bulbs. As soon as my 30-second delay on the exit lighting was over, or if I manually turned off my lights, I was able to then lock the car without issue.