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-   -   Trunk won't release/latch (https://www.mkzforum.com/forum/electronics/11914-trunk-wont-release-latch.html)

AJMKZ 01-05-2019 11:40 AM

Trunk won't release/latch
 
I can't believe there's no exterior key option at all. Basically, if the power trunk won't work, you have to crawl through the folding seat and manually release it with the emergency cord. This is a really horrid design.

A couple months ago, my power-down feature stopped working reliably. Then the power lift stopped working reliably. Both would still work occasionally, but not reliably. Didn't matter to me, I don't care if I have to manually lift or close the trunk,. and everything else still worked.

Then a few days ago, the trunk pop button didn't work. Used the remote - nothing. Tried a few times, finally worked. Didn't think much of it.

It's been getting progressively worse, and as of yesterday, i had to crawl through and pop the trunk manually twice while running errands. Thankfully it worked fine when I had customers with luggage. When it won't pop, it also wont cinch. Like, when i close it, it'll LATCH - but it won't motor down tightly and stays "loose".

Today it has stopped working completely. I had to crawl through to release it both on pickup and drop off of an airport customer - talk about embarrassing.

Everything says to disconnect the battery and perform a BCU reset, but I fail to see how that could change anything. The BCU seems to believe it's working, because when I use the remote to pop or close it, it flashes the lights and pretends it's doing the thing - it just doesn't actually do the thing. Weirdly, it also doesn't seem, to know the trunk is open. No warning message or lights, nothing saying the trunk is ajar - even when I *know* it is.

Anyone come across this before..? Is it a BCU issue, or should I replace the trunk latch motor? Why would the power up and down motor and the release/latch motor both crap the bed at almost the same time? Or for that matter - why separately? And why on earth would EITHER of these things affect the ability of the car to know if the trunk is closed?!

Help...

AJMKZ 01-14-2019 04:21 PM

Well this form is obviously dead, but for posterity if anyone comes across this on Google with a similar problem - I concluded that it was the motorized "soft close" striker assembly and swapped it out - and that wasn't it. Threw in the towel and went to Lincoln. Turns out that in addition to the multiple motors controlling the trunk lid lift/close, latch release, and soft close feature - there are FOUR SEPARATE control modules (located behind the trunk light in the upper passenger side of the trunk) for all this BESIDES the BCM - and one of them was malfunctioning.

Conclusion - the Fusion/MKZ with the "soft close" feature has the most over-thought, over-engineered, and functionally retarded trunk system ever devised by committee engineering anywhere.

Michael Dougherty 12-19-2019 12:37 PM

Trunk release malfunction
 
My wife's 2014 MKZ Hybrid has experienced problems during cold weather. The main control console functions (sliders, on/off buttons, etc) stopped working, and the trunk release also stopped working. She said it all started just as she was turning into the driveway and the auto headlights came on.

The Lincoln/Ford dealer had the car for five days (including the weekend, when they did not work on it) and they could not get it to fail so error codes could be checked. The service writer did witness the problem herself when my wife dropped the car off, but that didn't matter if the tech could not get it to fail during his troubleshooting activities.

The trunk latch behaved exactly as you described. The only way to get stuff out was to drag it through the fold down rear seat or to crawl into the trunk use the internal emergency release. The button on the dash did not work, the button on the remote did not work, the key code on the pillar did not work!

What were the weather conditions when your system failed?

Did you have any control panel functions stop working, or was it only the trunk release?

This car has been in the shop for this problem twice, both times during very cold weather.

The previous occurrence ended up with the shop replacing the 12V battery under the hood. They claimed that the battery was causing the problem.

Today the battery is still OK but the problem is back again.

After bringing the car home yesterday, it is still working "normallly".

It will be interesting to see what triggers the next malfunction.

I suspect that this is related to a control system circuit board that has a "cold solder joint" (a condition where a circuit "opens" as the board heats up and thermal expansion comes into play) or perhaps a relay or other active component that misbehaves under certain thermal conditions, right after a high current draw (caused by the auto head lamps turning on). I doubt that there is an error code that will actually reveal this kind of problem, which means that this may never get resolved.

I look forward to hearing from you... if there are enough people out there who are having this issue, maybe the Lincoln engineering department will take notice and issue a factory notice advising their service departments how to properly troubleshoot the problem.

2015mkz 01-21-2020 10:27 AM

I have the same problem on my 2015 mix, worked intermittently. Then one cold day it stoped completely. I have it warm shop and no change. Do you know what module was replaced? Sounds expensive...

Scott Williams 02-26-2020 08:46 PM

Trunk Lid Close Mechanism Failure
 
I had this intermittent failure until it became permanent.
Did the battery disconnect 3x to reset the lock -- NOPE.

The mechanism has 2 working parts:
1) The upper lid lock that grabs the bar at the lower unit base
2) The lower unit motor loop that pulls the lid closed snuggly below the twin spring flaps.

I used a nail to act as the engage bar for the top lid mechanism trigger to get it to close and used the FOB to open and release the nail. THAT worked. Half-way to the solution.

The lower loop bar motor mechanism that pulls the lid down tight was frozen "closed" below the twin flaps.
I saw RUST on the mechanism and liberally sprayed WD40.
Waited 10 minutes and with the upper lid mechanism OPEN I SLAMMED the lid closed HARD.
The lid grabbed the arm and locked.

--Before I tried this I lightly bounced the lid to see if it would catch -- and of course it would not catch because the loop was below the twin flaps in the locked lower position -- Hindsight would say "tap the par lightly with a hammer after a WD40 drowning" would also add the needed fix --

The force of the HARD close caught the loop and dislodged the stuck lower mechanism and the latch works now.
I continue to monitor the mechanism and spray White Lithium Greased and WD40 on it.

DANGED if it was nothing more than a MAINTENANCE issue to stay a step ahead of the rust inhibiting the metal movement.

kkizer 02-27-2020 09:23 AM

I am having the same issue, the trunk would intermittently not open or close, then the battery would drain completely if the car sat for more than 24 hours. Then the intermittent part became always.... Something else that I have noticed is that the settings in the menu for the trunk (power decklid) will not let you change them.

I took the car to the dealer and they have diagnosed it as a faulty trunk control module which will set me back $600.00. I will update this post after they have replaced it...

thanks for all the information!

Kevin Kizer
2015 MKZ

Lolopapq 05-16-2020 10:10 AM

I also recently encountered a similar problem. I was a little distraught since I had never encountered such a thing. But, at the same time, I fixed a lot of things because I like to do it. Soon I realized that I needed a suitable tool, so I bought a Hakko FX-601. Unfortunately, I didn’t know how to use it then and started looking for instructions. Thanks to the site https://solderingironguide.com/revie...fx-601-review/ which reanimated my trunk and me


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