HDJ81 RHD Driver Door Lock – What Controls the “Lift Handle to Lock” Function? (1 Viewer)

[Shaysoverlander]

Hey everyone,

I’ve got an imported RHD 1990 HDJ81 and I’m trying to better understand what specifically controls the behavior where the driver’s door will only lock if I flip the lock toggle and then close the door while lifting the exterior handle. From what I understand, this is a known quirk of JDM models, but I’m wondering if anyone has identified which part inside the latch or linkage system enforces this behavior.

I just rebuilt the driver’s door actuator assembly. I replaced the motor inside and everything seems to be working correctly. The actuator responds properly when tested off the truck, and it operates as expected when reinstalled. However, the electronic lock function won’t lock the driver’s door, whether it’s open or closed.

I have an aftermarket keyless entry receiver and key fob that I spliced into the door lock relay. It was working fine before the motor failed and I can use it to lock/unlock all doors but the drivers door. Now, the only way I can get the door to lock is by using the key or manually flipping the lock toggle and lifting the exterior handle while shutting the door this seems to align with the known JDM logic.

The actuator and latch look identical to pictures I’ve seen of US-spec FJ80 parts, but I’m guessing the difference is internal some kind of mechanical logic gate or cam that blocks the lock under certain conditions?

Has anyone:

• Pinpointed the exact internal piece (cam, spring, tab, etc.) responsible for this behavior?
• Swapped in a USDM latch to confirm if it removes this restriction?
• Successfully modified their JDM latch to behave like a USDM one?

Appreciate any insight or photos if you’ve dug into this before. I’m trying to decide if I need to source a US-spec actuator assembly/latch or just live with it.

 

[DivByZero]

It's not just Japan. All Toyota vehicles with manual door locks I've seen from the 90s were the same here in Australia, and honestly I didn't realise it wasn't worldwide until I saw this thread. It's supposed to make it less likely you accidentally lock your keys in the vehicle. It's a mechanical characteristic of the door handle mechanism, and happens even without central locking. If you don't lift the front door handles, the lock releases when the door is latched. Never studied the mechanism to see why, but you're looking for a mechanical linkage which forces the lock to release. The central locking triggering and unlocking the doors in your case is secondary - it's just triggering the unlock because it "saw" the lock get pushed into the unlock position.

 

[Irish Reiver]

Definitely not just a Toyota quirk. Every car we owned when i grew up in Ireland had the same locking principle. I always assumed the idea was not to accidentally lock the keys in the car.
Anyway, when i had an aftermarket remote locking unit fitted to my '94 I had the same issue. I vaguely remember the dude who fitted it having to splice a diode somewhere to override this issue. Sorry i can't help more that but it might get people thinking.

 

[Shaysoverlander]

Definitely not just a Toyota quirk. Every car we owned when i grew up in Ireland had the same locking principle. I always assumed the idea was not to accidentally lock the keys in the car.
Anyway, when i had an aftermarket remote locking unit fitted to my '94 I had the same issue. I vaguely remember the dude who fitted it having to splice a diode somewhere to override this issue. Sorry i can't help more that but it might get people thinking.

@Irish Reiver Thanks for sharing! If anyone has more details on adding a diode or wiring modification to override the driver’s door lock logic, I’d really appreciate it. Specifically, I’m trying to find a work around for this condition:
When all doors are locked and closed. Pressing the unlock button on the remote does nothing, the driver’s door stays locked and doesn’t respond (Two clicks are audible from the drivers door).

 

[Shaysoverlander]

It's not just Japan. All Toyota vehicles with manual door locks I've seen from the 90s were the same here in Australia, and honestly I didn't realise it wasn't worldwide until I saw this thread. It's supposed to make it less likely you accidentally lock your keys in the vehicle. It's a mechanical characteristic of the door handle mechanism, and happens even without central locking. If you don't lift the front door handles, the lock releases when the door is latched. Never studied the mechanism to see why, but you're looking for a mechanical linkage which forces the lock to release. The central locking triggering and unlocking the doors in your case is secondary - it's just triggering the unlock because it "saw" the lock get pushed into the unlock position.

@DivByZero Thanks, that makes a lot of sense and confirms what I’ve been piecing together. It seems like this lock-cancel behavior is mechanical, built into the latch or handle linkage itself, and not specific to just Japanese market vehicles. Appreciate the info that it's common in Australian-spec Toyotas too, that broadens the scope.
I’ll keep digging and post findings if I discover anything new. I would like to find someone with a US spec 80 and compare the linkages inside the driver’s door and compare the functionality with one that has an aftermarket remote key fob installed. I would love to hear from anyone who’s cracked it open and identified the exact tab or linkage that causes the lock to pop back up when the handle isn’t lifted. I'll post a cause/effect table I put together for troubleshooting.

Thanks again for the insight!

 

[Shaysoverlander]

If anyone has a US spec 80 with an aftermarket key fob and some spare time. It would be really useful to compare the results of these tests.

Scenario	Action Taken	Result	Driver Door Status	Buzzing Sound in Driver Door
All doors unlocked, driver door open	Hit master lock switch	All doors lock except driver door	Unlocked	Yes
All doors unlocked, driver door shut	While sitting inside vehicle, Hit master lock switch	All doors lock except driver door	Unlocked	Yes
All doors unlocked and shut	Turn key clockwise	All doors lock	Locked	Yes
All doors locked and shut	Hit unlock button on key fob	Two clicks heard in driver door, all doors remain locked	Locked	No
All doors locked and shut	Turn key counterclockwise	All doors unlock	Unlocked	Yes
All doors unlocked and shut	Hit lock button on key fob	All doors locked except driver door	Unlocked	Yes
All doors unlocked except drivers door	Flip lock toggle on driver door, lift handle, shut door. Hit lock button on key fob	All doors locked	Locked	Yes
All doors locked except drivers door	Hit unlock button on key fob	All doors unlock	Unlocked	Yes