make a conversion piece with the female Square end (second pic you posted) and then the round male end to plug into the Tekonsha RF or special LED reducer (then into Tekonsha).
that way no wiring gets cut on factory wire harness.

I wonder why North America has the round connection and you have the flat style? the 7 wires/pins provide same purpose.

We also have several versions of round connections as well (all have round pins though). I guess it is just how each country set up their systems in the first place. It's like why do we drive on opposite sides of the road, why do we have different TV systems (PAL vs NTSC). Each country has it's own quirks.

At the end of the day though, what I want to achieve is flicker free LED trailer lights and not have a great big lump in the middle of my trailer lead. If I can adapt something small(ish) and have it mounted on the trailer end and then a lead (pigtail) coming out and going to the vehicle, that would be fine. Alternatively, a lead with something in the middle which is not too heavy and may want to drag on the ground or foul with the trailer or towball.

If you have a digital multi meter measure the current going to the trailer (in U.S. You can plug in the ground 90° twisted and connect each of the other pins one at a time through the amps. If you send me that reading I will tell you the proper resistor you can put in parallel with the lamp to remove the flicker.


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I have 3 multi meters, but unfortunately they are all in storage along with most of my tools at the moment as we are renting a house while we build. I have had a look near the door of storage unit and moved a lot of stuff but haven't found one of the multi meters. It has been a pain not being able to get to all my tools. I need to replace the back wheel bearings on my E39 and my large socket set (need 36mm socket) is one of the first things I packed in the storage unit so it right at the back under everything else. Storage unit is 3m x 6m x 3m high (10ft x 20ft x 10ft high).

I can't justify buying a new multi meter when I already have 3. I have already bought a new soldering iron even though I have several in storage.

led trailer lights
 

Some quick math for estimating: typical incandescent bulb: 21w = 1.75A. Typical LED bulb 4w = 0.33A. That works out to 6.85 and 36 ohms

To make 36 ohms "look like" 6.85 ohms you need an 8.45ohm parallel resistance.

More than likely you can get by with half the initial current so rather than .875a I'll use 1a for a less wasteful solution.

1A takes 12ohm @12v. To achieve 12 ohm you put 18ohms in parallel with LED. That will put 8w on the resistor and be quite warm you need to assemble so it touches nothing and floats in space on the wire leads in open space so it cools.

8.5 ohm will be 18w very hot and hard to find

I would try a 15ohm 10w resistor that will get you over an amp and likely work. You can put two in parallel to get 5ohm 20w if needed.

At least 80% chance that 15 ohm will work. Try one as high as 20-35 ohm the higher that works the better. Less waste on heat.

Volt / res = amp. Amp x volt = power

Do The math to make sure power not higher than rated. The resistor will cook itself and can cause a fire. I use an app resistor calc to confirm values always.

-awr


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I have thought about the resistor idea, but heat is the issue. The other option is to install a secondary set of incandescent lights to my trailer in parallel with the led's. Even a row of globes would probably be less of a heat problem than resistors. Another idea is have low impedance relays across each circuit in parallel with led's. I am trying to find if there is plug in device similar to the one mentioned earlier that you have in America that I can adapt to Australian flat connector. I have seen on other forums that Ford sell a unit for a Ford Ranger that uses a 15 pin flat connector each end that I may be able to adapt.

I am starting to wonder whether it would have been easier to forget getting the proper trailer module and just wiring low impedance relays to the tail lights and indicators and using them to switch the trailer lights on.

LVP, how did you manage to plug the etrailer.com bypass module into your x5's harness receiver? the bulbous part on botton of that bypass is too big and strikes the metal trailer hitch receiver. SO I had to make an extension cord to use that bypass. I thought about cutting up the bulbous part on bottom of the bypass module to see if I could get rid of it but I figured it is there for a reason.
here is my harness I made from etrailer.com ordered parts.

OR now from e-trailer they made it super simple. Part C57003 is both an LED cancellor device AND extension cable. so it looks exactly like the part I made but with resistors built in so you dont have to buy the other part 20142 Like I did at the time. D'oh.

There is one line in my notes that explain it "The Tow Ready adapter goes between the Tekonsha box mounted on the trailer and the trailer cable. With nothing plugged into the Tekonsha, my signals didn't blink fast, so I knew the issue was after the Tekonsha unit."

I couldn't get it to fit in the X5 receptacle either. But, I plugged the Tekonsha into the X5 and the bypass module into the Tekonsha and the trailer wiring into that.Worked perfect.

that works with the trailer I have with the Tekonsha Prodigy RF, but for my other vrey light weight horse trailer that does NOT have the Tekonsha on it (potentially yet) the harness has tp plug into the LED error cancellation device that plugs into my extension harness.