Miserable door locks/remote issues

On my 2023 Tacoma Trail:

I will preface this by saying I've seen people say they act up when the battery in the fob is weak. Already replaced battery twice, tried both fobs, etc.

I am also aware that it must have sensors in the back seats because it will tell me to check the back seat if I park and I have some heavier items sitting on the back seat. (Though somehow through 5 children never have I come close to leaving a baby in a car)

When it began it was sporadic. It would happen for a few days and then go away for a week. Over time, it's gotten worse. The driver side rear door mostly. I won't lock with the fob. The other three will. I dont get the "beep" when I hit lock so I have to lock the left rear door by hand and then hit lock so the "beep" happens and the alarm will set.

Unlocking also does not work for the drivers rear door. Here lately it will randomly start to work for a week, but then back to not working. Happens with or without anything in the seat. At times this behavior spread the the passenger front door, although that isnt as common. Same thing--randomly stop locking and unlocking with the fob.

And yet another maddening thing is that at times when I go to enter the truck from that passenger front door, it will beep constantly and just flake out. At that point the remote wont have any effect and I have to run around to the drivers side and hit the ignition button.

What gives....
this is the only headache I have with the truck, but it drives me nuts. Could it be weight sensor related even if it doesnt give me the check back seat message? Can I disable that whole thing? Pull the seats and jumper the sensors?

Thanks in advance

 

You didn't say how long this has been going on, years, quarters, months? If only in the cold weather, depending upon where you live, I would suspect the motors in the lock mechanisms. By the way they are motors and not solenoids as in many decades ago.

What I took out of your post is that sometimes not all the doors lock and not all the doors unlock when using the FOB. There are suspect doors that misbehave more than others. My experiences with my truck's door locks have been good; another vehicle I have had not so much - I replaced the motors in the door locks of a few of the doors. My problems were also intermittent.

I suspect you are still under warrantee but wish to be able to replicate the problem while at a dealer or they will say "no problem found".

My understanding is that the Body ECU controls/sends the signals to the doors to unlock/lock when it receives the signal from the TPMS ECU. So, a weak FOB is not the answer as some of your doors never misbehave; from what I can tell from your description is only some doors misbehave while the remaining do as they are told.

 

I've had the truck for about a year and a half, since new. just hit 30,000 miles.
The weather is hot in the summer, cold in the winter, and it doesn't seem to affect things.

Driver's rear door: "most" of the time will not lock or unlock with fob.
Passenger front door: "Once in a while" will not lock or unlock with fob.

For the Driver's rear: It started out sporadically over a year ago--it would act up for a week and then act fine for a week. In the last 6 months however, it has rarely worked. Still there have been a couple stretches of a couple days where it worked.

For the passenger front: Took longer to happen for the first time--and that one only acts up one day a month I would guess.

I should have long since taken it to the dealer for this. I've run out of free service visits by now and I never thought to mention it during those. I will check into whether I am still under warranty for the locks.

As for duplicating it? The driver's rear door rarely works these days, so there is a 98.8 percent chance I can replicate that for them.

 

I agree that it sounds like the rear passenger-side door lock mechanism actuator may be bad. I’ve replaced them in Toyotas before, but not in one so new like yours. Definitely a warranty item if it’s bad.

To replace, you take off the door handle cover, the arm rest, and the door panel. The actuator is typically bolted to the inside of the door frame with three bolts in the door jam. I’d bet there’s a YouTube video somewhere. Good luck!

 

It sounds like you are not going to investigate this yourself, but if you were I would disconnect the electrical from the LR door and see if that rectifies the issue for the RF door. What I am thinking is the LR door motor is taking too much power from the circuit making the RF door slow to react. With the LR door disconnected the voltage would be higher and all doors may work properly.

This depends upon if you have any use for the LR door as it would have to be disconnected for some time to test this theory out since the RF door seems to operate fine most of the time. Unfortunately, the only place to disconnect the LR door wiring is within the door itself or to de-pin connector BA1, of which I have no idea where it is located.

The cause of the actual problem I will take a guess on: Toyota produced or sourced a bad batch of motors, or the grease was changed, and it is affecting the operation. Could also be a linkage/cable problem.

Another question, which you may have already covered is how do the locks react when operated from their own switches or from the master control on the driver's door? I have an AC so I do not know what the rear doors on a DC have. I suspect the rear doors do not have lock controls according to the schematic.

Another possibility is the vehicle's battery is going bad, i.e. low voltage.