Wish me luck, built my own trailer/hitch harness

[almstsobur]

I just couldn't justify $500+ for a few wires and plugs. The price of that harness is beyond stupid for what it consists of. So, I bought the trailer module, marked up the wiring diagram and put together a harness. I'll be be wiring it in the ride tomorrow morning and testing it out. I made all the connections removable so I can pop it out if I ever need warranty work. All the wires are the propper gauge, just not the propper colors. I used shielded CAT6, outdoor grade that's grease encased inside the shielding and has a divider between the pairs for the data buss connections. We will see how it goes.

RP

[nyalpine90]

good luck!

[crackerjack15]

I feel the same way. Most of the extra stuff for this vehicle is stupid pricing. My last 35i, I simply wired in a generic trailer add on harness locating the wires for stop/turn/tail and tapped them. It worked great since the battery is right there too. I only used it to tow a 4x8 utility trailer once in a while. I could give two shits less about the back up sensors alarming or the camera view.

[crazyinp]

Let me know how it goes. Seems like you might be local, so if you don't mind helping another member to put one together ?

[almstsobur]

Well, hardware is good, lights etc are working as expected. Plugging away at the coding now, shows as aag, but no ability to edit it. My coding experience is limited making changes to existing ecu's, so a little curveball adding an additional ecu.

Crazyinp, sure, I can help out. I'm in the Stockton area. I work in IT for a living, but tinker with electronics as a hobby. I've got a pretty complete lab in my house oscilloscopes, freqgens, ERSA stations, etc etc.

[Chadmatic]

Looks like you might have established a nice little niche... how much would you sell these for?

[wgxdz]

Just ordered a wire harness from Germany... cost me $400+

[Meehow]

I purchased mine from an online retailer, I paid a little over $400.

Good luck with building your own harnes.

[almstsobur]

Sorry for the delay, was out of town on the other BMW

Harness worked perfect, got the programming down as well. It's done, good to go. I ordered my Module from a BMW dealer in Warsaw Poland, $68 US, made the harness free, RV plug was $14 on Amazon and the Draw-tite hitch, $178. So, under $300 for the whole setup. I'm not the typical BMW owner; I use my blinkers religiously , I can only comfortably afford a vehicle like this a couple years pre-owned and because I will do everything myself, including all the service.

As far as making these, I would really need to buy the harness plugs to make that a worthwhile situation for any buyers. Otherwise it involves enough know-how that you could do the whole thing yourself, without my help. That or it would be a "mail me your module" situation. Though I would be happy to help anyone local-ish if time permits.

I'm happy with the outcome and I feel like it's a heavier duty setup than the stock one, at a far less total cost.

Thanks to all the forums posts that were a great help in the coding.

-RP

[crackerjack15]

Awesome job!

[Florida-X3]

Well Done! Glad my CPO came with everything OEM (except the receiver or ball attachment).

[spykes]

Hi can you repost the sheet of paper larger? it is hard to read and it would be helpful to recreate it.

[Caffeine]

How did you code it? Esys or bimmer code? what did you change?

Originally Posted by almstsobur

Sorry for the delay, was out of town on the other BMW

Harness worked perfect, got the programming down as well. It's done, good to go. I ordered my Module from a BMW dealer in Warsaw Poland, $68 US, made the harness free, RV plug was $14 on Amazon and the Draw-tite hitch, $178. So, under $300 for the whole setup. I'm not the typical BMW owner; I use my blinkers religiously , I can only comfortably afford a vehicle like this a couple years pre-owned and because I will do everything myself, including all the service.

As far as making these, I would really need to buy the harness plugs to make that a worthwhile situation for any buyers. Otherwise it involves enough know-how that you could do the whole thing yourself, without my help. That or it would be a "mail me your module" situation. Though I would be happy to help anyone local-ish if time permits.

I'm happy with the outcome and I feel like it's a heavier duty setup than the stock one, at a far less total cost.

Thanks to all the forums posts that were a great help in the coding.

-RP

[Garth2079]

That's a great job.

I'm trying to find the correct wiring to add a brake controller to my F15. Australian harness already fitted by the dealer (via previous owner) but no brake controller, and no 4-pin connector on the harness (and no wiring from the module to the brakes pin on the trailer connector). Can I ask where you got the wiring diagram? Which pin connects to the brake controller? If I can get the wiring, my mechanic is happy to wire it up, but otherwise it would involve bypassing the car's electronics and going direct off the battery, which concerns me. Any advice, diagrams, help to find the information in ISTA+ much appreciated.