Keyless Entry Stopped Working

[camion]

Two things:

1- Those coin batteries might read 3 or 3.3 Volts on a multimeter and still be bad if they're old. When in doubt get a new battery. Drove me crazy till I figured it out. The little red light is a good indicator. Also, like someone mentioned, a battery tester is a good tool to have. It puts a load on the battery.

2- Regarding the fob not working, I had that happen on my 4th gen and it turned out to be a severed wire that went to the running board lights (it was a Limited trim). The running board lights are on the same circuit as the fob receiver. Once I fixed the wire all was good. So maybe on the 5th gen there's something similar but harder to find.

 

[blksubykid]

This thread saved me a headache.. thanks guys!!

FOB went out this morning. I swapped “new” batteries but still nothing. I was going to just suck it up and manually lock and unlock the door but of course, forum said to buy different batteries and what do you know…works

 

[Lexington]

Ok I was having the same problem. I went down to Ace today to buy another brand. I had Duracells in my keys so I bought some Energizers and swapped them out. My problem is gone! I’ve tested it multiple times through out the day and it has worked perfectly.

So I was curious as to why Duracell battery were causing problems but not others. I found a very interesting answer.

I asked Grok this question and this was Grok’s reply.

Why Duracell (and some other brands) cause issues while others don’t
Many premium batteries like certain Duracell button cells (e.g., CR2032, CR2016, CR1632 — common in 4Runners) now include a bitterant coating (often Bitrex) for child safety. This is a thin, bitter-tasting layer meant to deter kids from swallowing them. 
In key fobs and similar low-power devices:
• The coating (usually on the negative/flat side) can act as a very thin insulator.
• It prevents reliable electrical contact between the battery and the fob’s metal contacts, especially under light spring pressure.
• This leads to intermittent failures — exactly as you described: works sometimes, gets worse over time, range drops, etc.
• Vibration, temperature changes, or slight misalignment make it unreliable.
Other brands (Energizer, Panasonic, or generic/high-quality no-name) often lack this coating or apply it differently, so they make solid contact right away. 
Some owners fix Duracell batteries by:
• Wiping the contact surfaces thoroughly with isopropyl alcohol (rubbing alcohol) to remove the coating.
• Or very lightly sanding/buffing the negative side (carefully, to avoid damaging the battery).
Duracell has updated some lines (e.g., for AirTags compatibility) to move the coating or improve it, but older stock or certain batches still cause problems in tight spaces like key fobs.

 

[hudsonwilson12]

I have had an issue ongoing for 2-3 years with my door locks. Truly just my driver and passenger doors.

2018 Trd Off-Road

The three rear doors (two passenger and one cargo) all work flawlessly with the remote lock and unlock.
The front passenger works 99% of the time for locking and 95% of the time for unlocking.
The driver works about 15% of the time for both.

Thinking it's something to do with the mechanism in the door, but not sure. Obviously receiver is fine, ECU should be fine, only thing would be the actuator or a small piece in the actuator. I've seen someone before say not to buy a whole actuator and just get a small piece that goes inside it. Does anyone know what this would be before I get 2 new actuators?

 

[henley]

Sounds like you’ve already ruled out most of the obvious causes. I’d be interested to hear whether it ends up being the key itself or the receiver.