Hi all. 
I know the boot unlocking itself issue is very common in fiestas! 
I have bought and changed the actual lock mechanism to no avail, the wiring has all been checked, all is good! 
still the fault remains! 
Any ideas anyone? 
I’ve googled it to death, watched videos on you tube but can’t get to the bottom of it! No way I’m taking it into Ford for them to rip me off!! 😞

When it happened to my old Mk7, it wasn't the lock mechanism or the wiring loom, it was the poor design of the switch itself- water gets inside and shorts it out.

It is possible, just, to prise the switch out from outside and fit a new one- new ones are pretty cheap on ebay- otherwise, you have to take off the interior trim of the boot lid and there are six bolts inside that hold on that particular panel.

Once removed it is possible to open the little screw lid on the switch unit and check the contacts inside, apply some vaseline, and re-seal the lid, but to be honest it's probably a better job to just put in a new switch.

This video shows a removed switch, and what is inside it-

https://www.youtube.com/watch?v=mu-MYcvmVdo

 

Amazing!! Just ordered this part from Amazon for £8!! Fingers crossed this solves it! 
I’ll post if it does as I know how frustrating it is when a fix is suggested and the OP doesn’t let us know if it works.. 🤣

Cool! I think mine was about that price, from eBay. It fixed my problem for the last couple of months I had the car. Here it is with the switch panel and switch removed-

 

 

Amazing! Thanks for that! 
looks complicated to get it off but I’ll follow that you tube video you posted! 
most helpful, thanks again 👍🏻

51 minutes ago, BlueMike2021 said:

Cool! I think mine was about that price, from eBay. It fixed my problem for the last couple of months I had the car. Here it is with the switch panel and switch removed-

 

 

Amazing!! Just ordered this part from Amazon for £8!! Fingers crossed this solves it! 
I’ll post if it does as I know how frustrating it is when a fix is suggested and the OP doesn’t let us know if it works.. 🤣

It's not as bad as it may look- you said that you have already replaced the lock, for that you will have removed the trim inside the boot, so you know how to do that already. Then it's just six M6 (10mm) nuts to undo, though one or two are a little tricky to get on.

Replaced the boot switch yet again on our car! Water had got in the genuine ford switch, purchased one off ebay and a year on the boot was popping open again, knew it was the switch.....''again'' 🙄 On the 3rd replacement I've wrapped sticky backed ally foil all around the switch joint, lets hope the water doesn't get in this time.

32 minutes ago, Ian Lanc said:

Replaced the boot switch yet again on our car! Water had got in the genuine ford switch, purchased one off ebay and a year on the boot was popping open again, knew it was the switch.....''again'' 🙄 On the 3rd replacement I've wrapped sticky backed ally foil all around the switch joint, lets hope the water doesn't get in this time.

which ones kept breaking genuine ford or the cheaper chinese ones of ebay? mine broke a few months ago and replaced it with a genuine ford one and is still working fine

15 hours ago, OvEr_KiLL said:

which ones kept breaking genuine ford or the cheaper chinese ones of ebay?

Cheap Chinese copies.
Looking deeper into the switch there's a little O shaped bit of copper with a contact point in the middle, the middle had corroded by the water ingress.

2 hours ago, Ian Lanc said:

Cheap Chinese copies.
Looking deeper into the switch there's a little O shaped bit of copper with a contact point in the middle, the middle had corroded by the water ingress.

do you reckon the ford genuine ones are better quality mate?

5 hours ago, OvEr_KiLL said:

do you reckon the ford genuine ones are better quality mate?

Well my genuine switch started to act up after about 8 years, the insides of the genuine ford and cheap copy look no different, it was the mating edges of the parts on the cheap ones that has allowed the water in.

3 hours ago, Ian Lanc said:

Well my genuine switch started to act up after about 8 years, the insides of the genuine ford and cheap copy look no different, it was the mating edges of the parts on the cheap ones that has allowed the water in.

cheers ian if it breaks again il get another ford one lol lets see how long it lasts

I asked elsewhere about the problem and they said to change the tiny switch instead, it looks a simple enough job and cheap too, so maybe I'll spend £1.90p on ten switches the next time.

https://www.ebay.co.uk/itm/333847986853

2 hours ago, Ian Lanc said:

I asked elsewhere about the problem and they said to change the tiny switch instead, it looks a simple enough job and cheap too, so maybe I'll spend £1.90p on ten switches the next time.

https://www.ebay.co.uk/itm/333847986853

lol ive never soldered man 🤣🤣

Well the part seems to have worked a treat, so thanks BlueMike2021!! 
I will bear in mind what people are saying about the cheap switches and if this one goes I’ll buy the genuine Ford part! 
Been trawling the internet for months to try and find a fix to this issue, and now it’s sorted! Saved myself a small fortune not having to take it to garage for diagnostic and repair! 

On 6/3/2021 at 1:17 PM, BlueMike2021 said:

Cool! I think mine was about that price, from eBay. It fixed my problem for the last couple of months I had the car. Here it is with the switch panel and switch removed-

 

 

Amazing!! Just ordered this part from Amazon for £8!! Fingers crossed this solves it! 
I’ll post if it does as I know how frustrating it is when a fix is suggested and the OP doesn’t let us know if it works.. 🤣

Hope it works ok for you! (This nice weather might give you a false impression for a while, but hopefully you'll be ok)

22 hours ago, BlueMike2021 said:

(This nice weather might give you a false impression for a while, but hopefully you'll be ok)

This is why I've wrapped my switch casing in sticky backed aluminum foil, hoping no water will ever get in.

When I unscrewed the six screws on the old switch I was shocked to see it full of water, When Ford designed the new fiesta they didn't think this very well through with the idea, the rear wiper surround has a gaping round hole, water & filth is allowed straight in, right over the boot switch and also to the rears of the number plate lights, I'm surprised no fuses don't get blown when the electrics get wet through ?

Yeah, it's a poor design. Mine was full of moisture rather than full-on water, but nonetheless it wasn't Ford's greatest idea!

On 6/6/2021 at 1:38 PM, BlueMike2021 said:

Yeah, it's a poor design. Mine was full of moisture rather than full-on water, but nonetheless it wasn't Ford's greatest idea!

Seeing your old car was just as bad as mine, all that build up of filth isn't the best environment within electrics, especially when wet through 🌧️ 🌨️

Absolutely. Rest assured, it went back together absolutely spotless!