Last year I purchased a towbar from Rendrag and he kindly provided some pen sketchings of how to wire it up . 
It didn't  quite match up with my existing harness , so I thought I might throw a line and ask others for input.
I haven't seen any threads on this subject as yet.

Before I start splicing, 
I'll be concentrating on the wires exiting from the top of the black box. 
left turn , right turn, stop and tail light wires are reasonably easy to follow and tap into, but what else should I be looking out for , Earth?
In Australia on cars, the earth is normally provided through the white wire.





I'm looking at picking up a trailer tomorrow with the K.
thanks Ed.

groverK wrote:
In Aus the earth is normally provided through the white wire.

At the bike the brown wire is earth.

Ed,
Forgive me if I am repeating what is already said.
Are you using a standard 7 pin plug connector?

The socket for most connectors comes with the wire colours coded or with a diagram in the box.

This one is Australian and shows what goes where. Hopefully the trailer wiring is done to match. Brown is earth on our bikes too so maybe you might need some coloured tape just to mark the wires.

http://www.campertrailers.org/trailer_wiring_diagram.htm

Not a good idea to attach the white trailer earth to the brown at that socket as the brown is only just adequate for the standard wiring and bulbs extend to and take it to the earth point at the gearbox otherwise the tail and brake lights can become a bit dull when the trailer is plugged in.

maybe a lug direct to the frame for the earth
there are a couple of bolts around there suitable ...the z frame hangers bolt would be one I expect

just a thought

I have to agree on the earthing. Should be easy to do as there are earthing points available, either at the hangers or the rear frame section. I have already put an earth there for the rear lights.

picked up a connector this morning, thought I might use one of these, rather than individual clips.


92, the trailer harness is the 7 pin flat type, as seen to the right of the fender extenda.


Inge , definately coplours can cause confusion , especially for new owners of modded bikes.
thanks Rick and Charlie,this was an area of concern , the earthing, 
 by suggestions so far, the brown bike earth is the only one I will leave untouched, and attach the white harness earth to a good grounding point at the tail.maybe the fender screw? does this sound correct?
I'm thinking of tapping into the existing wiring from the top side of the black connector.

I don't know how fond the BMU would be about the extra load, but I'm quite shure that Rick knows.

About your new connectors......I guess it don't rain that much down under,
but I wouldn't use these connectors exposed to the elements w/o som extra
protection.

Over the years I've had one lighting problem caused by trailer lighting. 

On a long trip the box under the seat that tells the dash warning light whether your brake lights are working or not burnt out giving meno tail-lights at all.  The cause: When you think about it the tail-light is 10W and brake light is 21W.  Add a sidecar and a trailer and the load is now 4 tail-light bulbs plus 2 extra lights for the trailer number plate (approx 40W total) and 4 stop lights (84W instead of the original 21).

Nowadays my trailer uses LED lighting which reduces the total load by a large amount.

Al

I fitted the block connector in place , and had to remove it , as there was no room for it.


it has been replaced by single connectors. wires are now shorter than I would like , not much room for tolerance.


A quick test resulted in all bike lights operating as they should , but no response from the 7 pin hitch harness. 
I used a light probe , prodding the middle earth pin , and making contact with pins 1,4,6 and 7, 
the earth to the bike may still need some attention.

 but it is good to have the connectors in place and the bike lights working.

92KK K100LT 193214 wrote:

http://www.campertrailers.org/trailer_wiring_diagram.htm

thanks 92 for the link. I found it helpful and interesting. although it is primarily based on the 4 tyre breed of campers , but still useful.

I was going to say there is no room for that but you found out the hard way
The BMU was OK with the extra load but the lights I had were crap so I put LEDs on and its much happier. The indicators were very slow as well and the LEDs sorted that out too.

think I can see your earth issue
the fender screw mounts into a plastic block and works by displacement of the screw to expand the plastic
as said before ....just to the right and a little to the front is the 6mm hanger bolts which connect directly to the frame .
use a standard eye terminal under the washer to get good conduction

good luck

ta, charlie , the fender screw appeared to be mounted to the rear tail frame with one of these on the steel frame


 which I gave a quick sand for contact, and used an eyelet connector.

Ed my 7 pin trailer connection is spliced into the harness wires as they run along the frame rail, right near the pannier mount oddly enough, with no external earth, may have to change that. If you want to drop by and we can do a test to both plugs and see what if any differences exist.

still might be better with the bolt mate ...6mm x 5mm of thread could be a bit better than compression contact only
but good to see the speed nut used

all done for now. moved the earth , as Charlie suggested, to the pannier frame bolt under the rear cowl.

I did test the earth through the towball , which is also attached via the same pannier bolt. No luck.
Ran a test probe from the pannier bolt to the number 1 pin (earth) where the trailer connects , positive result, with turn signals and taillights working.
I'm not happy with the white wire exposed though, for me it's a bit like a WHITE cable tie!!!!!!! just doesn't look right.

so the end result is , trailer harness wiring is easy . once you know how . Thanks to the assistance of fellow forum members.

WIRING YOUR K FOR TOWING A TRAILER
  installing  / wiring a trailer harness to your K100 / K75 / K1100


step 1. remove taillight to expose wiring under tail cowl.
step 2. BE SURE NOT TO CUT INTO ANY BROWN ( Earth ) wires. leave these intact.
step 3.    cut, strip and prepare the following wires: 
              left and right turn signal 
             brake (stop)and taillight (parking)
step 4.   with your hitch harness cable , strip and prepare the corresponding wires for connection, ie ; turn signals, brake , taillight , and earth.
             google : Trailer wiring   , for your colour codes.   
step 5.    crimp individual female connectors to all lighting wires leading on to your power source.
step 6.   start pairing up harness wires with corresponding light utilities,and twist together   
              ie; bike brake light wire with harness brake wire.        bike taillight with harness taillight etc , etc
step 7.   when pairing is complete, insert these into individual male connectors.           
step 8.    continue by connecting the previously prepared female connectors to the male connectors.
step 9.    find a good earth ground on the bike , such as the z frame bolt under the tail cowl, and attach the hitch harness earth wire to this point.

just remember , as pointed out previously , K bikes have BROWN earth wires, and trailer harnesses have WHITE earth wires.
so be careful when colour coding wires together.

step 10.   run a test on all lights and earthing, by means of multi meter or test light (with probe spike). I used the latter, it was simpler.
step 11.   reassemble all tail components .

you are now ready to hitch up your favourite trailer and start touring.

Keith do you experience any power drainage as mentioned by Inge?
I'm on the road to W'gong tomorrow to pickup the horse float , as Waz describes it. I agree.

The wiring to the trailer was on there when I bought it in 1994, it's never caused me any trouble. Pic looks like a pony float, you're kids will love that new pony.

"pony float" ,been there done that, this one is for camping, toolbox and pooch (Labrador) get a bout.
Could fit a few decent tarps in there for next weekend.

Let us know how the first ride goes, Mine was like 30 years ago on an XS1100 so its just a vague memory these days, OK its a lab float, mate sit the rear of the esky over the axle and fill it with beer and when the K boy's arive they will greet you with open arms. PS pack evenly but biased to give 20-30kg to the ball, ya wont know it's there after 10mins

good result ...ed ...onya mate !
but be warned
not all folks use the same wiring standards

be prepared to take the trailer plug apart and decipher the wiring colours .....
you might get lucky ...but from experience ...check first huh ?

Ahhh, you bought that one! I saw it on ebay and was thinking about it..

There's been a little tiny flat bed kinda trailer on the roundabout opposite bunnings every weekend for the last month, no price, but a 'make an offer, must go'..  Been seriously considering phoning the guy and offering him 200 bucks, would make a good start to a dedicated camper trailer

sound advice Charlie , so many different ways to wire up, this one proved easy.
 thats the one Damo , the shield is dead set ugly , but may serve a purpose later, the racks( roll bars ) can be useful .
very remenisce of a dog wash trailer with that door in the back end. maybe start up a sideline business for bike riding pooches.
and now you tell me there is something closer to home, send us a pic ,
 I'm still going to the Gong. any one up for coffee? I should be there around 8am.

Lol, I shoulda got the contact details today - will ask the missus to go down on saturday and get them!  All this packing this last week has got me thinking I should just bite the bullet and build a little camper..  If I can find an old canvas tent cheap, and ship it to dad in Ballarat, he can sew it into a new design for me on the old sewing machine he uses for leather.

I reckon that little 'float' would make a great camper with a few changes of the rear - set it up to have a fold out rear or something, and you sleep in there no problems   Dunno about the height though - seemed kinda high, not sure how that'd go around corners. Curious though, as I'd love to build a little camper trailer that has a winch-up tower on top for portable ham radio work when camping :-p

My camper trailer is up for sale at a very reasonable price.
If you are interested PM me
I will deliver it anywhere on the east coast for fuel cost.