Mk3.5 towbar wiring question

[Timgm]

I have just bought a Mk3.5 Focus estate and am in the process of fitting a towbar. We use it to tow a small caravan or a garden trailer. It also has a Witter cycle carrier bracket. The flanged towbar from my previous Mk2.5 fits exactly, so the towbar, towball etc are now in place. I am pleased to say that it doesn't trigger the rear parking sensors, even though the chunky cycle carrier juts out to one side of the towball.

The next thing is the wiring. Option 1 is that I reuse the two relays that were on the previous car and hook them to a 13 pin connector. That would mean that the parking sensors would trigger when reversing the caravan, but as we do that for about 10 minutes a year we could live with it. I am not too happy about tapping into the lighting wires, however.

Option 2 is to use a trailer module and dedicated wiring and there are several really helpful threads here about that for a Mk3, but my car's wiring looks different. I pulled off the side panel in the luggage area and found connectors taped up into the loom. Great, I thought, the car has trailer prep. So I unwrapped them, expecting to find a large grey connector and a smaller green connector. What I actually found were three connectors (picture attached).

The first is a large grey 2-pin rectangular connector looking like the ones other threads have shown. It has two thick wires to it - both the same size and both blue with a red stripe. Checking with a meter, they both go back to one side of the F28 position in the rear fuse box, the other side of the fuse being permanent 12V.

The second is a small black 4-pin flat connector with 3 wires: black with blue stripe, grey with orange stripe, violet with orange stripe. I guess these are a CANbus pair and something else - maybe a signal that ignition is on. Anyway, it is not the green 5 way connector I was expecting to find.

The third is a small grey 2-pin connector with a single thin blue wire.

So I am wondering whether the trailer prep on the Mk3.5 is slightly different from a Mk3, or whether the connectors I have are not for trailer wiring at all. I looked at the fitting instructions on the P F Jones website for their wiring kit and they seem to expect either a large 2-pin grey connector plus a 5-pin green connector or alternatively a 4-pin black connector (like mine) plus a 1-pin orange connector.

Can anyone shed any light on the wiring I have?

Any advice would be welcomed

Tim 

[Matt92]

@Timgm

Which side of the boot are those plugs? The trailer wiring is on the left hand side near the fuse box. Mine is a hatchback, but I’d imagine the wiring would be the same.

The big grey plug does look right, perhaps it’s just the green one is missing.

[Timgm]

Thanks for the reply Matthew. They are on the left side and it turns out that they really are trailer prep. In the hope it would work, I bought a wiring kit from PF Jones which arrived yesterday. It came with a short cable to convert my black connector to the green connector on their wiring kit. I just plugged it all together and everything worked. Strangely there is a flying lead on the green to black adapter which the instructions say is to be clipped to a wire in the wiring harness with a scotchlock to make the brake lights work. As all the lights work without it, I will just tape it up. It looks as though at some point Ford changed from having trailer power in the grey connector and CANbus on the green one to having power on an orange single pin connector and CANbus on the black one. My car must be in the middle of the change with power on grey and CANbus on black.

So the next job is to run the cable from the battery to the cable harness at the rear for the caravan fridge etc. Just debating whether to go under the car or find a way through the interior.

Then I will have to connect up to the diagnostic connector and activate the trailer bits of the system. That is something I haven't tried on any car yet so it will be a learning experience. If there was a way to turn off the reversing sensors I would probably leave it as it is, but there is no button to disable them and, in spite of what the handbook says, it doesn't come up as a driver assist option either.

 

[Cristian.Ionescu]

Hi, I have the same problem as you: black plug on the car, green socket on the trailer module. Did you solved this by only using the cable adapter from PF Jones? Can you send me some photos, or a link to this cable? I'm thinking to improvise something, it's impossible to find such adapter in Romania. I tried to connect them following the color codes on the cables. Still remains the 4th one flying as you noticed. On Forscan it's visible the trailer module but it cannot be activated. It's something that is missing me. Thank you in advance.