i've got a 1993 honda civic cx hatch back. there are two ways to unlock the glass half of the rear door (which you can then open to drop the tailgate and fully open the back): either a pull under the driver's seat or by turning the key in a keyhole on the exterior of the tailgate. rather suddenly, the exterior keyhole has stopped working but the pull under the driver's seat still works.

i can get the key into the lock just fine and rotate it about 15-20 degrees to the right but no further. it makes some crunching noises but it kind of always has. my first guess was that the lock was just gummed up, so i applied some powdered graphite lock lubricant (just the kind in the squeeze bottle, nothing fancy) and worked it into the lock with the key. nothing really changed. i then tried using the rake from a pick set to gently wiggle the pins inside the lock and get the graphite further in, in case one in particular was frozen. this also didn't seem to change much of anything.

since the pull under the seat still works, i suspect that the mechanism of the latch is fine and the problem is more confined to the lock -- but i have no idea how these two interact or if that's the way to think about it even. this is more in the category of a hassle than a real problem since i can still open the door, but it would become an actual problem pretty quickly if the pull also stopped working to open the rear door.

does any one have some ideas about what might be going wrong, or what i could try next?

 

If you suspect the actual key lock mechanism is the problem, soak it in WD40 by liberally spraying into the keyhole. Wait for 30 min to an hour, and then slowly rotate the key back and forth to break up the greasy gunk that is seizing the lock mechanism.

 

i can't believe i didn't think of this. i guess i've had a lot of years of being told to only ever put graphite in locks. i sprayed a tiny amount of PB Blaster on the key, gave it a few turns, now all three external locks work better than they ever have. thanks for the very simple fix!