Hello all! I'm hoping to troubleshoot an ongoing issue with my tailgate lock. I have read a lot of similar posts, but haven't found anything specifically about this combination of issues, and would appreciate any advice on where to go next with this.

First off, this is my first full post about an issue so if I've put this in the wrong place somehow or mislabeled something, my apologies. Please let me know and I'll try to get everything put in the right spot. I've benefited so much from all the knowledge and generous expertise on this forum since getting my 2000 4runner 3 years back, so thank you all for that and thank you in advance for weighing in here.

As the title suggests, I'm struggling with the tailgate. The lock is inconsistent. Basically every few days it will not fully unlock with the fob OR key OR power lock button, and I'll have to stand there unlocking/locking or jiggling the key back and forth in the rear lock for a few minutes to finally get it to cooperate. Usually it will after some fiddling, but I'm tired of it, especially since I have storage drawers in the trunk that contain a lot of important gear and can only be accessed with the hatch open.

I have opened up the guts of the rear hatch several times, cleaned, lubed and inspected all parts. Mostly things look okay once cleaned. I have done the following work in that area:

-Replaced license plate bezel with brand new OEM part (which gave me access to clean the inner locking works). 2021
-Replaced the wiring that runs down from the roof through the hinge into the window and locking mechanism with brand new OEM part. Surprised this didn't fix the issue, as the wires were visibly damaged at the hinge. 2023
-Have lubed the locks with fluid graphite (Lockease)

The rear window works, the rear wiper works, all three brake lights work.

However, I have noticed these other issues, and I'm wondering if they have any bearing on this:

-When I bought the car there was a crack in the license plate bezel that extended as a hairline up the door slightly, basically right where the lock is. It allowed a good amount of water in over the years, and there is some water marking on the door inside but the lock does not LOOK particularly rusty.

-When I lock the car with the fob, the right taillight does not USUALLY flash, unlike the license plate lights and left taillight. On occasion, very rarely, it will flash. What gives?

-The rear passenger door lock is lazy. Sometimes doesn't fully unlock when prompted. I imagine this is the motor in the actuator but haven't opened it up yet. Seems unrelated to the rear hatch issue but it is odd that it's on the same side as the brake light that doesn't flash when the car is locked.

BOTTOM LINE, I'm wondering what my priorities should be? I'm tempted to replace the whole rear locking mechanism, actuator and all, with brand new OEM but of course that's pricey. I plan to replace the motor in the rear passenger door soon, but I'd really like to prioritize the trunk before the warm months roll around again.

2000 4runner SR5, auto transmission. The only other electrical work I've done on the car is replacing the o2 sensors, replacing two lights behind the dash instrument panel, and putting in an ARB bumper--but I don't think those would relate to this? None of them seemed to cause any issues once they were done.

Thank you in advance! Let me know if other details would help.

I have the same issue on mine, it hates to lock.

Timmy the Toolman did a video on replacing the rear hatch lock actuator, which is probably what you should do next, but it's held in place by rivets, which won't be fun to get out.

I had some serious rust on my hatch when I bought it, so I'm just planning to replace it once I find a suitable donor, which should fix the issue for me.

Mine gets cranky after an offroad trip (lots of dust, I mean). I would look at cleaning and lubing all the pivots/linkages in the hatch cavity. That seems to help mine when it gets too bad.

A bad/weak actuator would exacerbate the issue, of course - but that doesn't explain why it is also hard to do with the key itself. Make sure you only use a dry lube (graphite powder) on the lock mechanism itself, otherwise it will gum up and stick.

-Charlie