Trunk Release Not Working (2018 Vert)

[CedarTree72]

Hello - recently, my trunk on my 2018 EB convertible was acting a little finicky, and now it won't work at all. Not the key fob, or the inner car release, or the hidden button near the trunk. To open it, I had to remove the rear seat and pull the emergency cord. The rear camera seems fine. Fuse 16 seems fine. Suggestions as to next steps? Something I can do myself, e.g., is it a simple part switch out? Thanks!

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[Cobra Jet]

IIRC; the rear trunk popper is tied into the same harness as the rear cam harness (and with a convertible the antenna).

Point being, that specific harness is problematic because of the constant bending from opening/closing of the trunk lid. If the harness didn’t have enough slack from the factory, it’s prone to damage.

You can’t tell visually from looking at that harness, the break occurs within the conduit - so it means you have to peel back the outer layer to find the wire breaks.

Pop the trunk lid and look for the harness attached to it. There are a few wires within that bundle. Peel the conduit off and look for any damaged wires or even broken wires. Examine the length of that harness, not just the part closest to the back (taillight panel) of the car, trace back further when looking for damages.

This thread shows how to do the DIY harness repair if you find breaks:
https://www.mustang6g.com/forums/th...op-working-heres-the-fix.117245/#post-2462302

 

[ORRadtech]

You can load the parts cannon if you wish. It may, or may not, fix the issue. Personally, I'd guess not though.
As Cobra said, just because one function works is not an indication that the whole harness is good. Since everything in the trunk is basically controlled by the BCM you have 3 basic options. Bad BCM, bad lock or bad wiring. I would consider the wiring most likely.
If you have the tools/skill set you can get a DVOM and test to see if the lock is getting the unlock signal. The following wiring diagram is from my '18 FSM, maybe it will help.

I am curious why the key release beside the back seat didn't work, I thought it was a mechanical release, not electrical?

 

[CedarTree72]

@Cobra Jet - thanks. Do you know what the grey thick wire is - it's very hard compared to the others, and I'm not sure it is a wire (versus just providing support?). It was the only wire (so far) that was obviously broken. And/or what are the wires I would need to splice for the trunk release? Thanks!

 

[CedarTree72]

@ORRadtech - it is a mechanical release but I'm an idiot. I finally found the key hole that does it.

 

[ORRadtech]

Just realized I linked the diagram for interior lighting. Sorry. Here's the one for the trunk lock/release.

 

[CedarTree72]

Thanks. That’s way over my head!

 

[CedarTree72]

Okay I tried a bunch of things and then got nervous to unwrap too many wires since I didn't want to risk messing up the back-up camera. So I took it in the local mech and he charged me $280 including diagnosing the solenoid, etc. Probably somewhat ripped off but I'm sure better than the dealer(?).

But he told me it was indeed two broken wires. Not sure why the recall only applies to 2017 and prior, but that's dealers for you...

 

[TasGT]

@ORRadtech - it is a mechanical release but I'm an idiot. I finally found the key hole that does it.

Hi I found the key release on mine behind the LH rear passengers seat and extracted the key from the remote but it is impossible to turn the key by hand and i don't fancy trying to turn it with a pair of pliers. Was yours very hard to turn?
cheers John

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