Hey FitFreak- my first post here, so please pardon any misconceptions.

For context:
I've got a 2008 Fit DX Manual trans and since I purchased it about 3 years ago (80,000kms) I've seemed to have almost every door lock stop participating in some form. The car's rear passenger door lock has never worked as far as I'm aware and that one I've accepted that it may be just the solenoid, or whatever electrical mechanism that actually pushes the door lock up may be dead. I've never gone as far as actually taking the solenoid out of the door as that task seemed too daunting with the amount of disassembly required, but I've gotten as far as taking the door panel off and poking around with my multimeter to make sure it's actually getting power, which it was indeed getting the 9V that it should've- at least at the crimp-connects half way down the door panel. Continuity checked out too, nothing was getting shorted to ground as far as I could measure.

Furthermore- within the last few weeks I've had the passenger door lock start going as well. Weirdly enough, the passenger door lock will actually unlock with my key fob, but something mechanical seems messed up with the actual locking mechanism as that one doesn't seem to want to go back down into the locked position without help from my hand. With that said, I can feel that the lock slider is met with some resistance near the bottom of the "locked" position which is where I think the issue lies as the solenoid probably just doesn't have enough force to push past it. Maybe a lubrication issue, I really have no clue.

Last but not least, the driver rear door no longer wants to fully unlock with my keyfob. It will lock itself with the fob but not fully unlock. The best way I can describe it is the door will appear in the unlocked position, but in reality, the position of the slider seems to be somewhere in the middle between the locked and unlocked position so much so that if you open the door with anything but graceful movements the slider will fall back into the locked position before the door can fully swing open and will stay closed, just not latched.

All in all, I've got three different combinations of the same issue across three of my doors. I have absolutely no idea if any of these issues are comparable, or even related to each other or not, but I thought I'd ask around here to see if anyone has some advice as to how I should proceed, or if maybe any of you have had the same issue and came up with a solution. Maybe the semi-functioning door sliders just need some lubrication, or maybe theres something else causing the non-working door to function altogether. I'm really hoping to get around to fixing these issues this summer as frankly, its quite the pain in the ass to have to reach around and unlock all the doors that dont want to unlock on their own, or even forget to lock the door that can't lock on it's own before leaving the car for the night.

Please feel free to ask any questions if I've missed some information that might be helpful to know, and I'll take any advice you guys have for me.

Thanks for your time! Cheers!

 

The culprit would likely be the actuator itself or the lubrication, as you guessed. I have pulled apart door mechanisms before to find caked up grease that actually prevented windows from rolling down, often times the compounds are similarly applied to door mechanisms. My suggestion is pull all 3 panels off, check for 12 volts, not 9. These are 12 volt systems and 9 is way too low. If all you have is 9, that sounds like a supply voltage issue. Secondly if that checks out, actuate the actuators themselves. With no resistance if the actuator hits full stroke with no issue, it's likely a weak actuator with resistance in the mechanism. At that point I'd grease up the actuators and just replace them as they're failing already. Good luck and let us know how things turn out.

 

Thanks so much for the reply. I think that'll be this weekend's project then now that I have an idea as to what to look for. I very much appreciate your insight! I'm going to look into the 9V thing I mentioned as well, again, as I assumed that was proper functionality, but now that you mention it seeing 9V in a 12V electrical system isn't right. Adding it to the list haha. I'll report back here if I manage to fix (or break) anything lol.