Hi all,

My 2013 Ecoboost Fiesta (about 100,000 miles) has a bike trailer connector, and all trailer lights have stopped working (braking, running, turning). Edit: this is a UK car. I can't pinpoint the exact moment the lights stopped working: I attached the bike trailer today after a year of not using it, and found there were not lights. Where in the two possible fuse boxes are the fuses and relays for the trailer/towing lights, and how are they called? I have looked through Ford diagrams online and nothing stood out with keywords "trailer" or "towing". I may have looked at wrong diagrams. 😞

On another (maybe related) note: while the trailer lights were still working, I noticed than whenever I would switch on a turn signal, a buzzing noise could be heard from the back of the car (same periodicity as the clicking sound for the turning light). I further believe, but I may be wrong, this tended to happened during cold or rainy wheather. I wonder if this symptom had anything to do with the lights now not working. The car was always garage-kept, no water damage.

Thank you in advance!

 

 

Trailer module - F20 - Passenger Fusebox

Though if it's an aftermarket towbar, it may not have the factory module.

It sounds as if you may have one of these relays fitted to your car for the trailer lights. These buzz or beep when the indicators are used while a light board is plugged in, so that the driver knows the trailer indicators are working.

https://www.ebay.co.uk/itm/311631953765?itmmeta=01J1F3RRZ50KM8650R4JX8Y4T3&hash=item488eb63f65:g:dQ4AAOSwx01jU8M6&itmprp=enc%3AAQAJAAAA0AoIQN8N%2B5993qaK2ow9aYk7ZLAyoAZLwxjaVJNmzfSWDlafNsVU0uOf%2BGJVvqgYlKr8vGZMBna%2FuO9irX2QSuVitYPXRLgGGm8grb1wnTL2MtKFOKEZBHcRNw68LwS%2BuWzknSGS%2BlZNT58AF4Y7f4Zixvg655WMtElTuOzV25%2BkE1IpupfXpb7qRpAFSPg0f24s%2FXczJfR3gl0iy%2B39LjC8ZFw%2B2h8aj%2BTXH8ahMYCeg7h%2Fhya%2FsfijbP1PgHa1lnm2BOSWw2c7TJBNRFM5IkA%3D|tkp%3ABk9SR9SP4-OLZA

You need to follow the wiring back from the trailer light socket, to see if one of these is fitted. If it is one of these, check that there is a 12 volt feed & earth to the unit. They should be wired through a fuse, so check for one if there is no 12 volt feed.

In addition to the above it is worth checking the wiring socket with a multimeter - including in particular measuring voltage against a separate ground - as they reside in a hostile environment and are prone to surface corrosion on the pins/sockets.

Thank you, all. I indeed will first check the wiring socket -- maybe it got damaged from driving in the snow etc. 

This was not an original Ford towbar and it was fitted at an independent UK shop for me. 

It's funny that the sound I described as annoying was actually a sign of the system working propetly :). 

6 hours ago, TomsFocus said:

Trailer module - F20 - Passenger Fusebox

Though if it's an aftermarket towbar, it may not have the factory module.

Would this be the correct diagram? 

https://www.startmycar.com/ford/fiesta/info/fusebox/2011#anchorfusebox0

This one does not mention F20, but it says "Trailer module" for two fuses. I expected to would be more than two fuses (breaking lights, running lights, power, turning lights, that's 4).

If it is an aftermarket installation then the permanent power feed could be from almost anywhere. Check both the engine and passenger fuseboxes for obvious signs of additional non-standard wiring being present, particularly a 'piggyback' fuse to tap into an existing or unused circuit. There will only be one fuse as, if a wiring bypass module has been fitted to avoid additional load on the lighting circuits, that's the only thing that needs a power source (which in turn will power the trailer lights). The car lights themselves already have their own power circuits - and associated (and, likely, multiple) fuses. It'd be be worth having a dig around behind the panelling in the boot area to see if you can find a wiring module.

18 minutes ago, runcyclexcski said:

Would this be the correct diagram? 

https://www.startmycar.com/ford/fiesta/info/fusebox/2011#anchorfusebox0

This one does not mention F20, but it says "Trailer module" for two fuses. I expected to would be more than two fuses (breaking lights, running lights, power, turning lights, that's 4).

Put your VIN in here to find the correct manual.  They get regularly updated through the model years.

https://www.ford.co.uk/support/owner-manuals

And as above, it's only the module that's fused.  There won't be more than one or two fuses for it.

Alright. I was hoping not have to pay to have this debugged (it's quite costly), but my own experience with car electrics is limited to having installed a CD player and speakers. Well, might worth poking around.

 

>>>It'd be be worth having a dig around behind the panelling in the boot area to see if you can find a wiring module.

MJNewton -- is this likely to be next to the passenger side fuse box? Maybe not, it would not make sense to run the cable all the way back across the interior. I should have asked the mechanic, and now that shop is long gone, and I have moved out of the UK across the channel (registered the car here).

It is more likely to be in the boot area given the co-location with both the towbar socket and rear light clusters, both of which it connects to. The only wire to be run from the passenger fuse box would be a 12v power feed.

Many thanks! If I manage to fix this, I will post an upate.