Perplexing Issue Locking Toyota Highlander

I have a 2012 Toyota Highlander with keyless entry and start. In August, 2017, the electronic locking stopped working. I could unlock it fine, just not lock it. The buttons on the doors and the buttons on both remotes gave the same results. I could unlock the doors, but could not lock them. Nothing happened that I could see or hear when the lock buttons were pushed. The only way to lock the car was to manually lock all 4 doors. At that point, pressing the lock button would in fact lock the rear tailgate (which does not have a manual lock) and the car would beep and flash to show that it had locked. I brought the car initially to my neighborhood mechanic and he says I need a new body control module and it would cost >$750, but that I needed that done at the dealer. I’m a cheapskate, so I waited 4 months before my wife yelled at me to finally getting it fixed as she was tired of manually locking all 4 doors every time she go out of the car.

This is where things get weird…I dropped the car off at the local dealer the night before as I could not make it in the morning the next day. Later that next day I get a call from the dealer and they could not reproduce the problem. Some how, after 4 months, it just started working again. I was happy, because they did not charge me anything. Of course, everyone there just thought I was an idiot and didn’t know how to lock my car.

The locks worked fine for the next 10 months until October of this year. While I’m on a family trip to the NC mountains the locks stop working again in the exact same manner…will unlock but not lock via the buttons. This time I make an appointment the next Friday (one week from the onset of the issue again). I drop off the car and show the service manager exactly what is wrong, so at least now he believes me. I then get a call later that day and the technician says he cannot reproduce the issue - it had suddenly started working again as soon as the tech had brought it back into the shop. I think that there is no way that is the coincidence considering the timing of waiting 4 months the first time and 1 week the second time these symptoms arose. I drive away, again without paying anything, hoping to get another 10 months of correctly working locks.

One week after I left the shop, the locks stopped working again - in the same manner. I make an appointment with the same service manager. I bring the car in (today), the service manager gets the experienced technician, and we show him how the locks are not working. He says its weird, but he would look into it. I get a call this afternoon and as soon as the technician drove the car into the shop, the door locks started working properly again!!!

The dealership and I are completely perplexed and have no idea what could be going on, so I’m desperately looking for help/suggestions other than getting an exorcism…

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I’m looking forward to someone having an answer, but it sure ain’t me.

Exorcism?
Sorry, I couldn’t resist. Intermittent problems are the worst.

Guess I was thinking about the movie. Lol.

Yes intermittent problems are bad but ones that automatically fix themselves by driving into the Toyota dealership bay??

The only thing I could think of tonight was what do techs do differently in starting or driving a car into the bay than an owner does. Most of the time I take it to the dealer, they turn off the radio but I have a hard time believing that has anything to do with it as the whole car if off with no power to the radio.

Are you leaving one of the fobs in the car but removing it when you take it in for service? Many new cars will not lock if a fob is inside…

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Perhaps a broken wire in the driver door harness where it flexes making intermittent contact?

Something is happening when the dealer gets it. The 2 most probable things would be moving the seat and changing the tilt on the steering wheel. Play around with those just for kicks.

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I like that thought. moving one of those could be hitting a wire.

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Sometimes a repair shop will keep the driver’s window down to avoid an accidental lockout. Does it make any difference if you try that?

Maybe even slamming the hood!

Many cars won’t lock remotely if all the doors don’t report as closed. Perhaps this is as simple as a faulty door closed switch. It might be hard to tell since these switches can have a bad spots along the travel where it seems like it should be in the closed position.

I actually think it is slamming the door. Something is not tight in the driver door and the dealer tech slamming it (it is not his car!) fixes it.
Next time this happens, just slam the door.

All good ideas. I’ll try them all and see if I can reproduce the issue. Right now the locks are working fine but just a matter of time until they stop again.

Any resolution to this? We have a 2012 Highlander (Hybrid) and it’s got the exact same symptoms, right down to every little detail. The doors will unlock fine, but only the rear hatch will lock. The remote and the power door lock switches on the doors are behaving the same, they can unlock but won’t lock. The only way to lock the four doors is manually.

No amount of moving the seat or operating the window caused any difference.

Pressing the lock button on the remote, with a door open, causes a long continuous tone, which I understand to be correct behavior. So the remote itself works, the car hears it. It just doesn’t lock the doors.

I checked the fuse descriptions in both the owner’s manual and the inside cover of the fuse boxes (three of them) and can find no mention of power door locks.

I physically removed and checked a couple fuses anyway and found no issues. Put the cover back on and it still wasn’t working.

Then as I was standing there looking at the fuse box and muttering and pushing the lock and unlock buttons, it magically started working. I mean, literally one press of the lock button on the remote did nothing, the next locked the doors, and I wasn’t touching anything at the time.

Still working today, but I know the problem will be back if I don’t solve it.

So I’m really interested in what the final resolution was for the original poster, if any.

I did finally get this diagnosed and fixed. Unfortunately, it ended up being the computer. It cost me $1,100 for the computer and labor including diagnostic time. Expensive but cheaper than buying my wife a newer car.

Yeah what all the others said but if you had a wiring schematic, one of the first things would be to clean all the contacts and check wiring. As far as the computer, you could always try a used one out of the junk yard.

I just wanted to follow up on this, in case anyone else is having the same issue and finds this thread. In our Highlander, it was also the body computer.

Considering the price of that computer ($757 list), I wanted to make sure before I went and bought one. So I bought a service manual on CD, which provided tons of information like pin-outs and so forth, as well as showing me where the body computer is located (under the dash on the left side). With a little probing, it became obvious that it’s inputs were good but it just wasn’t putting out the pulse to unlock the doors.

The parts book may refer to the body computer as a “junction block”. Which is what it looks like when you see it. It’s a cream colored box with tons of connectors on both sides and some relays plugged into it and the whole bottom of it is a small fuse box. It’s not terribly hard to get to it. You don’t have to pull the whole dash, just the bottom portion of it on the driver’s side.

There are about a dozen different part numbers for that computer, and it’s not written on the unit, and which part number you need depends on the market the car was sold into and how the car is optioned. I couldn’t figure it out for sure online, and I finally gave up and went to my Toyota dealer with my VIN and he looked it up for me. But of course he didn’t have one in stock and he said it would take weeks to get one. I came home with the part number and found it online for $520 shipped and had it a week later. Installed it in a couple hours and the wife is happy, she can lock her doors again. I think I’ve got husband points for at least the next year.

Thanks for pointing me in the right direction!

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I have a 2005 Highlander and just starting to have this same quirky little problem.

Car unlocks with the fob normally; no problem. But, when I use the fob to lock the car; the lights do not flash, the doors lock then about 5 seconds later, unlock on their own. To be certain, I now have to lock the doors all manually. I tried disconnecting the battery for a while to see if this would ‘re-boot’ the system but it made no difference. Does anyone have the part number for the ‘junction box’ that appears to be at the heart of the issue?