Hi guys, just a quick one. 

 

Ive got a mk3 focus estate, titanium x

My rear passenger door doesnt respond to anything, no windows no central locking and no keyless entry. 

 

The door modules work as i swapped it with the drivers side rear and it works. Fuses are all good

Im not confident in checking each wire separately to see the issue. 

Ive looked at a diagram of the bcm and read this is where the loom originates for the doors. Is the drivers side and passenger side rear connection to the bcm the same? If i swapped them over i could determine wether its the loom that is the issue, then i know i can get a second hand loom to sort the issue. 

 

Central locking connection to the BCM is with one multi-pin connector which has around 30 wires. It would be very difficult to swap the different door locking sides.

The usual place to find damaged or broken wires for a fault like this is where the door harness connects to the body 'B' post.

Hi, thanks for the reply, busy Christmas so havent had chance to look into it yet but will look for a new harness from the pillar and see of that does the job in the new year

The rear passenger side door module is controlled by the front passenger side door module.

Front passenger side door module = Master -> Rear passenger side door module = Slave.


All commands are digitally transmitted to the front passenger side door module. This door module processes the data and controls the rear passenger side door module.

Check if the rear passenger side door module has power. If it has power you either have a broken communication wire between the front and rear passenger side door modules (highly unlikely) or a defective front passenger side door module (much more likely).

16 mins or so in.. check that  out.  Very common. 

Wiring harness where it enters into the car down behind front seat belt mounting. This is how mine stopped working.

On 1/30/2026 at 10:08 PM, Aego said:

Wiring harness where it enters into the car down behind front seat belt mounting. This is how mine stopped working.

So finally got around to looking into the issue.

I have found two issues. The first is.what has happened to you!! Pulled the connecters and 2 pins had corroded.

The second issue, which seems more annoying and frustrating is the previous owner must have known this after looking himself and the connector in the pillar is damaged, the the point of if i were to clean the corrosion the damage to the connecter would not stop any further damage.

Would anyone know what the part number would be for the internal wiring harness? I was thinking of trying to find one second hand and splicing the connector onto the original wiring

Finding part numbers of wiring harnesses is extremely difficult.

During production Ford installs dozens of different part numbers with different configurations for a particular type of harness. Which part number gets installed depends on the trim level and optional extras that were specified when the car was ordered. Ford does not register which exact part number was installed during production.

As a replacement Ford only lists a single part number. This is the latest, most complete harness that replaces all harnesses that were used during production.

The part number listed in the parts catalog is different from the harness that is currently installed and is therefore not really helpful to find a replacement harness. Based on the part number listed in the parts catalog it is highly unlikely to find a used replacement at all since these fully wired replacement harnesses are extremely rare.


Each wiring harness inside the car has a label with the exact part number. Finding the label however can be a pain since quite some disassembling/assembling can be involved to be able to locate the label.

On 4/4/2026 at 11:04 AM, JW1982 said:

Finding part numbers of wiring harnesses is extremely difficult.

During production Ford installs dozens of different part numbers with different configurations for a particular type of harness. Which part number gets installed depends on the trim level and optional extras that were specified when the car was ordered. Ford does not register which exact part number was installed during production.

As a replacement Ford only lists a single part number. This is the latest, most complete harness that replaces all harnesses that were used during production.

The part number listed in the parts catalog is different from the harness that is currently installed and is therefore not really helpful to find a replacement harness. Based on the part number listed in the parts catalog it is highly unlikely to find a used replacement at all since these fully wired replacement harnesses are extremely rare.


Each wiring harness inside the car has a label with the exact part number. Finding the label however can be a pain since quite some disassembling/assembling can be involved to be able to locate the label.

I can confirm everything you said to be correct after spending a good part of easter sunday trying to find something lol.

I didnt get a notification about your comment otherwise i definitely would have given up.

Finding the correct harness thats inside the door would be easy as i have that part number, but there isnt any 'used' available online only direct from ford, which is actually a lot cheaper than i imagined at £57. But paying for this wont solve my issue as previously stated, although pins are damaged on this side, the other side is damaged beyond usage too.

My other plan was to create my own connections, bypassing the connection blocks fitted. Turns out upon inspection that there are more wires that come from the car than the harness inside the door has. So that plan is thwarted.

From my understanding, the model and trim level i have has all off the extra options installed. Ive messaged a few ford specialist breakers too see if there is a work around