Solved: Aftermarket trailer wiring - shop won't do brake input?

[RhythmMachine]

Called the local hitch shop to see how much it would cost to get a hitch and wiring in for an X5 I'm considering buying, and they said that they don't wire in controllers for BMW because of the coding that needs to be done. I'm pretty sure I still have ISTA and WinKFP on an old laptop, so should be able to do that myself, but the wiring they'll run up under the dash is for power and brake output. They said they don't do the ground (which I should be able to figure out) or the brake input on BMWs.

Any idea if wiring up the brake input line for the brake controller is relatively straight-forward as a DIY?

[Attacking Mid]

It's no different than any other vehicle if you are not using the BMW harness and trailer module. Ideally, though, the best setup is to get the actual BMW harness and trailer module, then code it into the system. The wiring up front for the brake controller will be the same regardless which way you go.

AM.

[ard]

DO NOT let them touch your car. They are hacks. Period.


They are telling you they will run wiring 'under the dash'? They are hacks.


Just buy the BMW AHM module. plug and play. Seriously, try and find a pdf of the instructions, it is all done at the rear of the car- a module, some wires, gromets- a bracket on the hithc for the plug. 2 hrs if you are drinking.






IMO


My brother tried to safe a few $, had Stealth install their own interface. (X15) A year later he drives 700 miles to pick up a trailer- right signal not working, stealth module failed- he only had 4 hr window and was unable to fix it (I trouble shot it to a SStealth failure, not wiring). They wouldnt rent him the trailer, he drove home with 30% of the load he had planned, all inside his X


Had he installed BMW, any BMW dealer could fix it. (and it likely wouldnt have failed)

[andrewwynn]

Run vin decoder to find if your car has the harness prewired for adding trailer.

I needed to tow a trailer didnt need brake so for under $100 bought a perfectly usable 4-pin trailer wiring I keep inside the car until I need it then pull it out the bottom of the hatch.

That said I do want to upgrade to the bmw solution to get braking control. I spent a long time trying to find the module online with no luck so I'm still using the 4-wire.

[workingonit]

Originally Posted by andrewwynn

Run vin decoder to find if your car has the harness prewired for adding trailer.

I needed to tow a trailer didnt need brake so for under $100 bought a perfectly usable 4-pin trailer wiring I keep inside the car until I need it then pull it out the bottom of the hatch.

That said I do want to upgrade to the bmw solution to get braking control. I spent a long time trying to find the module online with no luck so I'm still using the 4-wire.

On my 2001 E53, the previous owner (my former neighbor, with an electrical engineering degree) installed an aftermarket hitch and rigged his own 4-way wiring so I could be able to tow able a small 4.5x12 utility trailer w/o brakes (that came with our vehicle-for-vehicle, trailer-for-trailer swap), overlooking the fact that I needed a 7-way to tow my 4x8 home-built camping trailer w/brakes.

I never really asked how it was set up (with three relays), figuring that when I needed to change it over to a 7-way to tow my squareback 4x8 with, he'd be able to re-configure it for me (I'm not now, nor have ever been, an EE). But, he seems to have moved far away, and changed his phone number, so I'm not sure how to proceed to rewire for a 7-way.

The X5 didn't come prewired for towing, and like you Andrew, I've not found the factory wiring harness for sale (though I've seen AHM modules for sale on Ebay), so I might try an adaptive harness from etrailer.com Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires Item # ETBC7. I found it while searching under the "for 2001 BMW X5 without factory Tow Package" header.

I've installed many controllers and 4 and 7-way wiring harnesses, but never have seen relays used


I guess I can just try and see if the ETBC7 Universal wiring kit will work (it has three circuit brakes included...maybe what the relays are somehow acting as in the mystery wiring I already have??).

Another alternative that might work is the Tekonsha 119190 ModuLite HD Plus Trailer Light Protector with Power Module, which I could install in place of the PO's 4-way wiring, then use the ETBC7 to add the 7-way capability. The ModuLite unit says it will work on BMW's

[andrewwynn]

Tekonsha 119191 ModuLite HD Plus... https://www.amazon.com/dp/B001P2DUM2...p_mob_ap_share

That's the one I used for 4-pin. It does a perfect job at what it's meant but I do want to get the bmw solution so the car will factor a trailer into dsc and not beep constantly when backing up etc.
Anybody know a source for the correct module for 2011 e70? I found for other years not 2011.

[ard]

OP-For some reason I assumed all E70s had prewiring. Sorry if I led you astray....


Andrew- Also surprised that the module is year specific....
Part#: 71-60-6-850-497 seems to be called out for many years- 2009-2012???


https://parts.bmwmonterey.com/p/BMW_...606850497.html


(Crazy price- ebay is 1/4 give or take)




Would this do the trick if you didnt have pre-wiring? or is this only for those with PRE wirie??


https://www.bimmerworld.com/Body-Aer...rt-Aero_2.html




Thx all

[andrewwynn]

Not the module the wiring kit.

https://www.ecstuning.com/b-genuine-...s/71602156526/

Supposed to be the wiring kit for E70 but when I drill down to my model or says doesn't fit.

My car is "pre wired" for the harness but I don't know what kit I need.

The kit above includes the picture of the module but no bullet list of the parts.

[Attacking Mid]

I'm guessing that fitment exclusion is a mistake. It seems there was only one kit for all E70's. Here's a cut/paste of the installation instructions that has a CR date of 2012 that seems to indicate it fits all E70's.



  DO IT RIGHT THE FIRST TIME, ON TIME, EVERY TIME  



Installation Instruction P/N 01 29 0 439 467
 2012 BMW of North America, LLC

Installation Instructions 1 of 23

June 2012
Equipment Parts, Trailer Hitch Ver 3.0 Accessory
Development



SUBJECT



TRAILER HITCH KIT (US Only) - P/N 71 60 2 156 525





MODEL



X5 (E70): Select Vehicle Production 10/06 - On*
X5 Diesel (E70): Select Vehicle Production 10/08 - On*
X5 M (E70) Vehicle Production 07/09 – On

* Not for vehicles with BMW Performance Aerodynamic kit.





SUGGESTED INSTALLATION TIME: 2.5 HOURS**



**Suggested installation time includes re-coding of the vehicle only for this retrofit kit. This time is based on a
vehicle that is at the current software level and does not require any updates.





Please refer to SI B09 05 01 for latest BMW approved Retrofit coding procedures.




Total installation time may vary depending on vehicle options and equipment.





The instructions below are developed for BMW vehicles and are not to be compared to any other existing
instructions for vehicles other than BMW. No methods other than those specified in this document are to be used
for installation in BMW vehicles. Left and right are determined from the driver’s seat.



Carefully read all instructions and supplements before proceeding with the installation. Reference should be
made to TIS for instructions dealing with a stock part of the vehicle but not stated in detail in these instructions.



The instructions were complete and up to date at time of publication; however, changes to the vehicle or
installation may have occurred. Please report any problems or changes noted with the installation to BMW
Technical Hotline, along with VIN, date of manufacture and as much detail as possible.







Note: Pages 22 and 23 (BMW X5 (E70) Trailer Hitch Guidelines and Cautions) of these
installation instructions should be given to the vehicle owner (customer) after installation
of the trailer hitch kit for approved towing procedures.
















2



Installation Instruction P/N 01 29 0 439 467

PARTS INFORMATION



Contents of Kit - P/N 71 60 2 156 525



Description Qty BMW Part Number
Cross Member with Receiver Tube 1 71 60 0 440 592
Cross Member Mounting Nuts 8 71 60 6 772 024
White Capacities Label 1 71 60 0 413 357
Receiver Tube Cover/Cap 1 71 60 0 303 882
Electrical Kit 1 71 60 2 156 526
Contents of Electrical Kit:
Trailer Control Module (AHM) 1 61 35 9 186 177
Trailer Hitch Wiring Harness 1 61 12 2 155 760
7-pin Trailer Wiring Connector 1 N/A
7-pin to 4-pin Trailer Wiring Adapter 1 72 11 0 404 323
Hardware Kit 1 N/A





ADDITIONAL REQUIRED PARTS



Description BMW Part Number
Rear Bumper Trim Piece Kit (Vehicle 04/10 – On)
Rear Bumper Trim Piece Kit (Vehicle 10/06 - 3/10)
Rear Bumper Trim Piece Kit X5 M (07/09 – On)

71 60 2 185 557
71 60 0 035 371
71 60 2 185 556
Rear Bumper Trim Piece Kit X5 M Sport Package (ZMP) (04/10-on) 71 60 2 230 141
Ball Mount Kit 71 60 0 413 358







ADDITIONAL OPTIONAL PARTS



Description BMW Part Number
Electric Trailer Brake Controller 82 11 0 420 082
3 ft Trailer Connector - 4/5 Wire Flat*** 61 13 0 412 965
5 ft Trailer Connector – 7 Blade Round (Female) 61 13 0 412 966
5 ft Trailer Connector – 7 Blade Round (Male) 61 13 0 412 967



*** Not for use with trailers with electric brakes.




AM.

[RhythmMachine]

I think I'm getting a better understanding... I want to get the "full" factory functionality (no audible proximity alerts on reverse when trailer is attached, backup camera zooms to hitch area)

- physical hitch doesn't have to be OEM (needs to be fit for purpose and properly installed)
- brake controller doesn't have to be OEM, can be either wireless or hard-wired
- feature coding does have to be added after to enable "trailer-specific" functions (disable backup proximity alerts, zoom to hitch area for backup camera)


Is that right? If so, I only need someone else to install the hitch and controller, and I can do the coding/turn on the features myself. Beyond the disabled proximity alerts, backup camera behaviour, and dash warning messages for defective trailer bulbs, are there other aspects of it? Does it change stability control behaviour, brake balance, or other things?