2015 Fiesta Zetec 1.25. Boot won't open. I first changed the tailgate switch. Still didn't open. Then changed the boot lock mechanism. still didn't open. Went to car electronics specialist, who ran the checks and said it was the BCU module. after buying online, garage fitted and programmed it, told me it was working. Got home it wasn't. Now spent over £200, and boot still won't open.

a) How can the doors locks open remotely if BCU doesn't work?

b) if it's BCU, can another fault ( a short) short out the replacement, if so why only the boot opening, everything else worked on both BCU's. I don't want to spend £300 on a new BCU ( + garage told me there's a long waiting list since so many break?), only to have another fault (short) instantly break £300 of parts.

C) Is it easy simply to fit a new switch ( on dashboard, under car seat etc) to bypass the BCU etc totally. ie a positive manual switch wired directly into the lock mechanism to get around this. The lock mech has four wires, which colours would need to be changed (bypassed) removed etc to bypass current issues, with a new switch ( yes it means I can't open the boot from the key, and might only be open boot with ignition on, but that's fine).

D) any other solutions. I'm long term unemployed and the money already spent with no results is more than i could afford. Really need help here guys.

Thanks.

 

STOP. 

There has been too much random guessing and no fault finding. 

First put all ideas out of your mind about fitting switches and bypassing this or that. The lock is also part of the the vehicle alarm. 

So you say there are 4 wires connected to the lock. Have you got a multimeter? 

You need the circuit diagram for the car locking system, probably available in a Haynes workshop manual. 

I will see what can be found and then you can look for the fault.