Avoiding American tow bar faux par…

[Martin Hocking]

I’ve been molesting my American pick up to deal with some issues- mainly rust related, though one of the non rust related tasks is sorting out the tow bar wiring. It’s a bit messy, it’s got at least two too many sockets, all three of them a bit crusty and wiring that already looks like I did it in places! I’d tell you if I had honest I would!

So the pick up is a 1998 Ford F-150 and came with a factory tow bar when it was built four score and seven years ago…
This has a main wiring connector which deals with the rear lights and trailer socket.


When it was imported it would appear that a fairly hasty conversion to a double seven pin uk tow bar set up. With a caravan relay thing tucked up in the near side rear light.


What I’d like to do is fit a single tow bar socket and make it a neater less convoluted arrangement.

As I remember it the current lay out went with a 12v ignition live tapped out from the us trailer socket and an extra 12v constant live plumbed in. Both running to the relay thing in rear light. Feeds are then plucked out of the lights for the brakes and indicators etc.

(I’m pretty sure that’s pizza dough not leprosy before anyone suggests hand cream!)

What I wonder is whether it’s possible to make better use of the original Ford wiring for the American socket?

A quick internet search came up with this info on wire colours:

color code for the factory sevenway
white = ground
Blue = electric brake
orange = hot line (Battery (+) ignition controled
brown with white trace = running lights
yellow = left turn
Green = right turn
last one is backup wanna say its black with a green trace

(Taken from THIS forum thread)

Which seems to tally up with what I have going into the socket.

So to me it seems like most of what I need for a basic seven pin tow socket is there in the Ford wiring, and the extra 12v feed means a 13 pin is pretty feasible too. Even though I think I’d rather die than have a caravan it might be useful all the same!

I know in the states that brake and indicator lights are share a pin in the trailer socket is there something different in the way the circuit functions that means it won’t play ball with a uk socket? I’d be using the electric brake wire for the brake lights.

I’m doing my best impression of someone who has a clue so any advice is greatly appreciated…

 

[Erie Fred]

I use Etrailer.com for my goto on wiring diagrams:

https://www.etrailer.com/faq-wiring.aspx

https://www.etrailer.com/faq-wiring.aspx?__cf_chl_tk=JMAqRYvSNMNUQ..Jvk3Fx4OJeBXyD5yleo1ASF3.5ms-1770730197-1.0.1.1-nQkoTb_MzD49Fx3Zcp0gsX.OcHBUuKwJsUr5koADh6c#connectors

Note on the 7 pin there are (2) different diagrams, RV & AG.
As you are removing all of it, the pinouts of the connectors are not really needed.

Your rust is not much at all for a vehicle that old BTW.

I would neaten the wiring up with a connection box:

https://www.etrailer.com/Accessories-and-Parts/etrailer/e99009.html

as this wiring is at the very back of the truck, and get's blasted with salt & grit
coming off the back tires, I like to use the box, as well as position a rubber/plastic
flap over the whole assembly (use tye wraps) to make a shield.

 

[Bullet2012]

other useful options with 13 pin are reverse and fog lights for the trailer.
best check mot status as if the socket is visible i understand the mot people test the functions and that all must work

 

[Blobber]

other useful options with 13 pin are reverse and fog lights for the trailer.
best check mot status as if the socket is visible i understand the mot people test the functions and that all must work

I believe its only 13pin that need to work for the MOT

 

[Bullet2012]

I believe its only 13pin that need to work for the MOT

I understand , only if visible, don't believe tester can remove anything to test

 

[Erie Fred]

I did a bit more looking on the Etrailer site.

Looks like way back in 1988 there was no custom made
wiring harness for it.

Back then I had to cut & dig into the wiring harness as well.
Custom aftermarket wiring harness's/adapters are a newish item.

I would rip it all out, and start poking in the connector
with a test light, not that hard of a job to do.

Reverse should be in that connector IIRC, but no fog lights, so you'll
probably need to run a new wire thru the loom, up to the front for those.

 

[Bobupndown]

So the pick up is a 1998 Ford F-150 and came with a factory tow bar when it was built four score and seven years ago

87 years ago?

 

[dave h 2]

other useful options with 13 pin are reverse and fog lights for the trailer.
best check mot status as if the socket is visible i understand the mot people test the functions and that all must work

You needn't fear that, the 13 pin is massively more reliable than a 7 pin. My Jeep came with a double 7 pin set 2 years old back in 2016, on the 3rd year the 7 pin quit . It's been 13 pin since then no issues.

 

[Bullet2012]

i was not eluding to the reliability, more to the fact that the required functions of the 13 pin must be working for MOT

13 pin Euro-socket​

On vehicles fitted with a trailer 13 pin Euro-socket, use an approved device to check that the socket is wired to correctly operate the trailer:

• position lamps
• stop lamps
• direction indicators

Some 13-pin test tools may continually flicker when plugged into the socket of a vehicle that uses controller area network bus (CANbus) systems.
Where this happens, it generally indicates that there’s continuity at each pin on the vehicle’s socket. When the lamps are operated in turn you will usually see that each individual LED will function correctly.
Provided the self-test facility on your tester does not show any faults, then you should pass the socket test.

(a)(i)	A trailer electrical socket insecure	Minor
(a)(ii)	A trailer electrical socket likely to become detached	Major
(b)(i)	Trailer electrical socket wiring insulation damaged or deteriorated	Minor
(b)(ii)	Trailer electrical socket wiring insulation damaged or deteriorated and likely to cause a short-circuit	Major
(c)(i)	A 13-pin trailer socket not functioning correctly	Major
(c)(ii)	A 13-pin trailer socket not functioning at all	Dangerous

[th]

Defect reference​

[/th][th]

Defect​

[/th][th]

Category​

[/th]​

 

[atomant48]

I re wired my trailer a couple weeks back. Even though I had a wire diagram it depended entirely on which way you looked at it so I had alotnof fun getting the pins right.

As mentioned above I believe you need a fog light for uk but not a reversing light.

Oh and I had to change from LED to normal lights as it kept throwing faults up on my car. Apparently there’s an interface box you can fit - maybe build this into your wiring if you’re re doing it all.

 

[Bullet2012]

believe you need a fog light for uk

if fitted it must be working

 

[bricol]

Unless someone done something interesting with the wiring to the turn signals in that loom, I think you will find it easier to still pull a suitable signal from the tail light turn signals - assuming they do actually operate separate from the brake lights?

With my Dodge, I was already using relays to operate my brake lights (triggered from the central brake light) and turn signals (triggered from the front turn signals) - both requiring relays to switch the warning light circuit to ground when in operation to prevent bulb-failure warnings, so I simply piggy-backed from them to operate the trailer lights.

With hindsight, I could probably have used one of those solid state towing relay units to do quite a lot of it in anyway.

 

[dave h 2]

i was not eluding to the reliability, more to the fact that the required functions of the 13 pin must be working for MOT

Which does elude to the reliability

 

[More Amps]

Or even allude...

 

[Martin Hocking]

Or even allude...

I do love how the forum comes with auto correct!

 

[Martin Hocking]

Thanks for all the reply’s forumites, they’re all very helpful.

@bricol and @Erie Fred can either of you explain what actually happens on an American trailer with combined brake and indicator light? I can’t quite figure out in my head how that works.

If I can help it I’d like to try and avoid using the brake light, indicator and rear light signals directly from the lights themselves as it was a right pain to get the carapace off with the umbilical cord off tow bar wiring!
Although I could solve that by doing a better job in the first place!

Reverse and fog lights are extras and fitted below the tow hitch. So tapping into those won’t cause s problem.

I don’t know if it had reverse lights originally, I sort of assumed America is so big nobody ever needs to go backwards!

 

[Martin Hocking]

And @Erie Fred regarding rust I couldn’t decide if it was better or worse than I expected when I got a good look at it…


But thankfully the back half is on its way back together again now…

 

[Bullet2012]

I do love how the forum comes with auto correct!

Yes its extremely handy that and the grammar corrections, shame its so slow on occasions , maybe woz or malcolm can sort it

 

[dave h 2]

Thanks for all the reply’s forumites, they’re all very helpful.

@bricol and @Erie Fred can either of you explain what actually happens on an American trailer with combined brake and indicator light? I can’t quite figure out in my head how that works.

If I can help it I’d like to try and avoid using the brake light, indicator and rear light signals directly from the lights themselves as it was a right pain to get the carapace off with the umbilical cord off tow bar wiring!
Although I could solve that by doing a better job in the first place!

Reverse and fog lights are extras and fitted below the tow hitch. So tapping into those won’t cause s problem.

I don’t know if it had reverse lights originally, I sort of assumed America is so big nobody ever needs to go backwards!

Red indicator lenses same bulb

 

[dobbslc]

But thankfully the back half is on its way back together again now…

What did you use on the chassis?