The door lock on the rear passenger's side tries to unlock when I unlock all the doors, but moves a little and goes back down. It can be pulled up by hand. I suspect this is a lubrication problem, which might be fixed with a squirt of WD-40.

Anybody know how to get quick and easy access to the lock mechanism to give this theory a try?

 

If it's a lubrication problem, I think you'd notice excessive friction when pulling it up by hand. That's vs. a weak lock-motor or something like that. Still, I think you have to remove the inner door panel & have a look.

 

Would it make any sense to squirt a little WD-40 at the base of the lock, where it enters the door frame? The lock feels a little harder than the others to lift manually.

 

Here's what it looks like. The little pin (#4) is all you see, and squirting in there would get all over everything & probably not help.


With the inner door panel off, you can lubricate the little crank #14, but more important you can get to the mechanism #7 also.

And I think WD-40 would dry up & not work very long. A drop of engine-oil would work much better on the crank, maybe a bit of lithium-grease for the moving parts of the mechanism(#7) especially if they're plastic.

Also get the push/pull rod from the actuator #9 over to the mechanism #7, in case that's sticky also.

 

JimBlake - thank you for that excellent analysis! I'll be taking my car to the shop!

 

I'd probably hit all of those areas with silicone spray, as that won't attract dust and dirt. On my 99, it's the same door and lock that does that. I haven't messed with it, since that door hardly ever gets used (it's been locked since April).

 

I noticed that when I tried to manually cycle the lock many times to possibly free it up, that the FRONT lock didn't work for a while! This suggests that maybe that these locks are powered by some kind of independent battery, and that this battery may have just lost its effectiveness over time. Anybody know if this is true?

 

I don't think so. As far as I know, there's only the car battery under the hood in these cars.

 

You may have a problem with the door lock actuator on the rear passenger door. There was a DIY fix on older generation accords, but I'm not sure if this applies to your 99. Do a quick search on google to see if it applies to your car as well.