Thanks to the people that wrote up this DIY.

A few things I want to add onto the post:

1. be very careful when removing the plastic piece before getting to the actual metal frame, as those 4 metal-on-plastic clips that holds it in place can be easily broken.

2. before taking apart the small unit (the white box), try freeing the arm by moving it forward and backward.

3. if you do need to take the small unit apart, chances are, there is a weak tooth within the gears. I ended up just tearing off the semi-broken tooth and everything works like a charm.

also, based on looking at the pics posted, it's the same tooth in the gear that seems to jam up the mechanism.
took me about 30 minutes to take apart, fix, and put back everything together.

 

Thanks guys work great for me, the rubber grommet that limits travel looks like it gets worn and the quarter gear moves beyond its limit and jams, I cut a bit of eraser and put that in place of the rubber stop appears to have done the trick

 

This thread helped me greatly! I was able to take the gears apart and put back together with no trouble at all. Trunk now closes and opens better than before

 

Great thread! Thanks for all the advice and pictures were perfect, helped me figure out there was a missing piece, that was up underneath causing it to jam.

 

Man, am I happy I found this thread! Worked great. Thank you all for your inputs. I will say at one point when I was putting the plastic trim back on I stepped away from the car and the hatch slammed shut on the trim.. chipping the hole where it locks. If it's not one thing, it's another :-(. Oh well, I'll take a chipped piece of plastic if it means my trunk can stay shut!

 

I was ready to visit the dealership until i stumbled upon this. After hearing that it could cost a couple hundred dollars, i decided F*** that, and did it myself. My problem was that the trunk would not close or stay latched, so it would bumb up and down if i were to drive. Also when parked the trunk would not lock, hence ... granting overnight access to the inside of my car.

Thank you so much for this thread. It gave me the confidence to open the motor/actuator up myself, move around the cogs, and surely it was an easy fix I had no idea that this problem was so common. My trunk had been finicky since i bought the car a couple years ago and now its working better than ever.

Also TIP for everyone: That spring might be causing your problem. I had to pinch it to get the "arm" working again.

Thanks again!

 

Just adding my thanks to this thread. My 07 trunk decided to stop working while at work. Would not close just bump up n down. I thought I would have to spend a few hundred, not to mention drive back home 36 miles with a bumping trunk. Read this thread and while at work, took the thing apart. Turns out the spring was all the way stretched so when i opened the box and reassembled the gears it relieved the tension. Working great and saved me 300-400 bucks!!
Also thanks for the pictures made a big difference.

 

So my trunk button never worked and as of last week during my brake job my trunk started spazzing out and kept going off randomly every few seconds. So that has been going on for a week or so and now it doesn't work at all anymore and the trunk is stuck open. Help me! Suggestions?

 

I would try to remove the motor/actuator and check on it to make sure none of the teeth have jumped or like in my case that the spring is stuck in the stretched position. You've got nothing to lose and could save you a few hundred if it is something simple like that

 

Just used this guide to fix mine.

Same issue as everyone else with the broken tooth. Works well now.

Thanks all.

 

Thanks for the tip! I had the same problem, broken tooth in the small gear. It was caused by the black stopper wearing down too much, causing the gear to overextend, which put too much pressure on the end teeth breaking them off. I just turned the black stopper sideways so its bigger section was stopping the gear. Took no time to fix.
Love these forums!

 

This thread has helped another Z member out, ME!.. This just happened yesterday to my 2008 Nismo, with 51k miles. Luckily nothing appeared to be broken in my actuator. I just realigned the gears in there, put it back together, and now it works just as good as it did before. Thanks!

 

This totally saved my *** today. Got home and went to close the hatch and it just bounced up. Followed these instructions and in about 30 minutes it worked. Thanks a TON!

 

Ha! You too eh? I have the same mileage on my 2008 Nismo.

 

My 2008 Nismo with 89,000 miles just had the actuator fail. Opened, found no broken or worn parts, joggled it and verified full range of motion, reinstalled. Then 3 days later it's acting up again. I'm paying the $156 at Courtesy...

 

Same here. My actuator failed at about 100K miles. I removed it and everything looked OK. I reinstalled, and it failed again within a few days. I ordered and installed a new one. That solved the problem.

 

I'm thankful for this thread. My back hatch has been banging all week while my guy has been looking for an actuator ($150-$200). My '04 350Z has 185,000 miles and the hatch has finally stopped working (won't close). I stumbled upon this thread and a novice like me was able to fix it in about 45 minutes. I would not been able to do this without Yellow Stealth's pics and the ongoing confirmation from others.


This is how the quarter gear looked when I opened and removed the top gear.




I was able to easily move the gear to the proper position and put the top gear back on.

 

Bumping this for record and visibility. Having the issue now, will post pics if/when resolved. No socket wrench at the new house yet so have to get a set.

 

The EXACT same tooth is broken on mine, I will try a similar solution!

 

So here I am 4 years later experiencing problems with my trunk that wouldn't latch again.

It's funny that I had to go back and find my own instructions in this thread to remember how to fix it. This time i do not have any broken teeth, but thanks to Chico007's pictures, I realized the quarter gear was stuck in the wrong position. I have now fixed it!

We'll see how long this fix lasts as my experience has found that a misbehaving gear tends to break down within months of the initial symptoms. Fingers crossed.