Bimmerfest BMW banner

1 - 20 of 24 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter #1 (Edited)
When I recently decided to purchase a semi-lightweight travel trailer, I assumed it would be an easy thing to add a hitch with full trailer electrical and brake functions to my 2015 X5 35d. Little did I know I was wading into one of the more controversial and complex aspects of owning an X5...

Is it an abomination to have a visible hitch on a BMW? Should you tow with an X5 in the first place? If you get past these issues, then you're dealing with what hitch is best? OEM? Invisihitch? Something else? And then if the hitch decision wasn't painful enough, you need to figure out what wiring harness is the right choice? OEM? Aftermarket? Active? Passive?

There are nearly as many opinions about what is best as there are options. In one sense, that means there are a lot of good options and what is "right" may come down to exactly what the needs are. For me, my needs drove the decision and I'm very pleased with the end results.

My needs/wants:
  • Trailer dry weight - 4,000 lbs
  • Tongue weight - 500 lbs
  • Trailer braking - Yes
  • Preferred brake controller - Active hardwired (not an inertial bluetooth unit)
  • Chassis or bumper modifications - No
  • Preferred hitch ball - 2-5/16 inch
  • Preferred hitch features - Load-leveling and anti-sway
  • Car integration - to the greatest degree possible, but willing to compromise
My desired hitch ball size meant the OEM hitch with its 2" ball was out of the question. Similarly, my desire for load-leveling and anti-sway features meant solutions from Invisihitch or some of the other hidden hitch designs would get very complex. That left me looking for a Class-III hitch that could install without modification to the chassis or bumper. After reading a lot of reviews of various hitches, I settled on the Curt 13077 hitch.

After weighing several wiring harness options, I decided to go with the full OEM setup. This meant the OEM harness, the OEM hitch control unit, and the OEM brake controller (Tekonsha head with the proprietary BMW cable).

After calling a local hitch installer and getting quoted over $1700 and 5 weeks for the parts, install and coding, I hung up and decided to do the job myself. Here are the parts used and where they were purchase from:
  • Curt hitch - Part# 13077 - $193 through Amazon
  • OEM tow hitch wiring harness - Part# 82-71-2-349-500 - $216 through Irvine BMW
  • OEM trailer hitch control unit - Part# 71-60-6-884-357 - $85 from a wrecking yard
  • OEM brake controller and cable - Part# 82-11-0-420-082 - $210 through Suburban Auto Parts
1008797


When the 47 lb package from Curt arrived, I wasn't disappointed. The quality of design, welds and finish on the Curt hitch were all outstanding. I was even more impressed when I realized they had included replacement plastic fasteners for the wheelwell trim - unexpected and truly a great addition to their hitch package. The other items all looked in great shape as well, but I will say the hitch harness raised my eyebrows as I realized I would have to add some pins to some existing vehicle plugs to complete the wiring. I was hoping for a plug-n-play install, but it is slightly more involved than that.

Removing the rear bumper fascia without damaging anything is a PITA, but doable in an hour or so being very careful.

I followed the excellent instructions from invisihitch for most of the job. They truly do a fantastic job walking through every step. I also used the BMW instructions for retrofit of the OEM removable trailer tow hitch. Although these instructions are not for the exact hitch and harness I installed, the harness is substantially similar and these instructions showed how to complete each of the pins into the back of the fuse panel, which is a bit different than for the Invisihitch harness.

The Curt hitch installs onto the factory studs for the rear bumper crash bar (it replaces the bar) and was a perfect fit - slid right on. After torquing the 8 nuts supplied with the hitch, I began the wiring installation. The wiring in the luggage compartment all went without a hitch (no pun intended).
1008798


I did have some difficulty finding the vehicle connector for the Body Domain Controller, as it was hidden inside the chassis harness and wrapped in tape. You can see it in the lower right of the image above, after being exposed.

Here is a closer view of the Body Domain Controller connection.
1008799


I also had some difficulty reading the pin numbers on the CANBUS terminal plug behind the fuse box. Two of the OEM towing harness wires must be pinned into this connector and figuring out how the connector was numbered required a magnifying glass. Below is a cheat sheet on how the pins are sequenced for anyone trying to do this task (these pinouts are required for almost all active harness designs, not just the OEM harness).

1008802


After this, completing the wiring inside the vehicle was mostly straightforward. The finished install is very clean, with the brake control plug easily accessible for whenever I am towing.

1008803


The external wiring was a different matter. The Curt hitch tucks in so tightly under the bumper fascia that there is no place to mount a hitch plug bracket on the hitch itself. Hanging the plug on a bracket below the bumper is ugly (my opinion) and also there is the problem of there being no substantial structure in the bottom of the bumper fascia to attach a plug bracket into. For this reason, I designed a bracket which adds some structure to the bottom of the bumper and holds the plug receptacle in a way that is hidden when it is not being used.

1008804


This required a curved sheet metal bracket with some welded stiffeners on it to keep lower fascia from flexing when inserting the plug and when carrying the weight of the heavy trailer wiring over rough roads.
1008805


This curved sheet bracket was epoxied to the inside of the bumper fascia and was extended far enough outboard to catch the first support screw between the fascia and the chassis insulating panel. It is not pretty when viewed from inside the bumper, but I wanted to corrosion-proof the steel bracket as well as I could, given its location.

1008806


The final install looks about as good as I could have hoped, given the fact I now have a permanently visible 2" receiver under my bumper. The Curt design tucks the receiver up exactly to the point where it is nearly touching the bumper and also holds it back under the car about as far as is practical. The Curt hitch does all it can to hide the receiver, short of going to the hidden hitch design.

1008808


1008809


Finally, even without encoding the control unit to the vehicle or doing any coding, most of the tow functions came alive after install. All trailer lights work and the X5 recognizes when a trailer is attached and disables rear PDC, replacing the radar PDC graphic and alerts with a tow symbol. The camera zoom feature did not activate and I suspect the active suspension features have not activated either. I am getting a "Hitch Wiring Failure" amber warning on the dash which made my heart sink a bit, but when I check the codes the only fault present is that the control unit is not encoded to the vehicle. I will get the box encoded and any needed features activated in the coming week or so and hopefully that will finish the job.

Total cost: $789 + another $100 or so for coding.

Total time: About 7 hours and 2 of those were spent fabricating the hitch plug bracket.

Next report, I will let you know how the 35d pulls the trailer when fully loaded - I expect this will be around 5,000 lbs. I have high expectations from this little diesel, I know. If it feels a bit anemic, I will be working on the ECU next!

Hopefully someone will find this useful and don't hesitate to hit me up with questions.

-PNWX5
 

·
Registered
Joined
·
6 Posts
Your post is both useful and timely, thank you so much for taking the time to present this information in such a thoughtful, thorough and organized manner. Kudos to you for doing the installation yourself! I too have waded into the complexities of sourcing and installation of a tow hitch for my X5.
An invisible hitch and/or one where cutting wasn't involved as well as OEM components was my first choice however neither is available for my 2005. In actual fact, the options all around are pretty limited for anything before 2007. After much research I settled on a Curt C13162 and Curt components w/the exception of the brake controller - not being keen on the bluetooth is as far as I've gotten in the search. Of most concern, weighing heavily, is the "coding". I've been told that the BMW dealership needs to do it (the hitch installers won't touch it) ; I've been told by the BMW dealership that they won't do it unless it's BMW; I've been told that due to the earlier year of the car it may not need coding at all. I'm confused.
Like yourself, I was systematic in the way that I went about pairing the tow vehicle w/the trailer. As I had purchased my 20' toyhauler (3760 dry) first, I sourced the vehicle w/the proper towing capacity around that. I then tearfully parted with my '93 525i touring and went on to purchase my '05 X5 4.4i with 38,000 miles (which I love!). It all would've gone as planned had it not been for the snafu with the hitch.
Any information that you may be able to offer, especially on the brake controller and on the mysterious "coding" would be very much appreciated.
 

·
Registered
Joined
·
5 Posts
Discussion Starter #3
Hi missharron. Im not sure how software driven the 2005 X5 is, but it may not matter. The reasons to do the coding on the 2015 may not even be relevant to the 2005. Coding deals with these features on the F15:
  • Disable rear park distance control when the trailer is connected
  • Enable reverse camera zoom
  • Activates the towing function in the dynamic stability control system
  • Activates sensing for a trailer light being out
I’m not sure if these features exist on the 2005. If they do, then coding is beneficial.

In the case is the 2015, if you want the trailer brake controller to connect through the OEM harness, then you need to add a separate BMW hitch control box (a computer that controls the hitch functions) and have it encoded to the vehicle as well.

Hope this helps.

PNWX5
 

·
Registered
Joined
·
287 Posts
Nice write-up.
I was fortunate to be able to get my Invisihitch install done by Steve and his crew before that business closed. Went with the BMW components and have been very pleased with the outcome, and not one issue.
Keep us informed on your install.
 

·
Registered
Joined
·
6 Posts
Hi missharron. Im not sure how software driven the 2005 X5 is, but it may not matter. The reasons to do the coding on the 2015 may not even be relevant to the 2005. Coding deals with these features on the F15:
  • Disable rear park distance control when the trailer is connected
  • Enable reverse camera zoom
  • Activates the towing function in the dynamic stability control system
  • Activates sensing for a trailer light being out
I’m not sure if these features exist on the 2005. If they do, then coding is beneficial.

In the case is the 2015, if you want the trailer brake controller to connect through the OEM harness, then you need to add a separate BMW hitch control box (a computer that controls the hitch functions) and have it encoded to the vehicle as well.

Hope this helps.

PNWX5
Thank you for your input. It does help as support for possibly not having to have the coding done due to the earlier, less software driven year of my car. I would be so relieved. I'll know more today after a trip to the installer (luck was w/me as I was made aware of a BMW- specific specialist who does hitches). I'll take your list in to him and hope for the best.
 

·
Registered
Joined
·
6 Posts
Nice write-up.
I was fortunate to be able to get my Invisihitch install done by Steve and his crew before that business closed. Went with the BMW components and have been very pleased with the outcome, and not one issue.
Keep us informed on your install.
Yes you were lucky! I got so excited when I saw the chart on their website confirming that it would work for my car... only to deflate when I learned (through a forum here) that they had closed. You were also lucky to get the BMW components, you must be driving something later than a 2007.
 

·
Registered
Joined
·
287 Posts
Yes, mine is a 2015 diesel.
 
  • Like
Reactions: missharron

·
Registered
Joined
·
1,414 Posts
X5 is great tow vehicle. I towed over 20k towing miles with my E70 35d a 33' long trailer. The weight around 7,000-7,200 lbs ready for camping (sometimes over 7,500 lbs). My tongue weigh it around 800-900 lbs. I use ProPride weight distribution hitch and wireless Tekonsha 90250 Prodigy RF brake controller. I towed through Rockies, over 10-12 times through Sierra Nevada. Absolutely fun to drive.

Your trailer is fairly small / light, therefore, you should be OK without weight distribution. However, if you dry weight is 4,000 lbs I doubt that you will be at 500 lbs tongue weight ready for camping. This would require VERY thoughtful packing, but even then without some mods I am not sure you can get there. This would also depend on the layout of the trailer.

OE harness is no brainer. Regardless of the hitch you would be using. If planning to use weight distribution, OE hitch (or Stealth hitch) are not an option.



 

·
Registered
Joined
·
6 Posts
So good to hear about your experience with the X5! Thanks so much for sharing the photo of your rig and the youtube. Weight distribution - I'm wondering now if I should've gotten that. Is it something that can be added on later? The trailer is a toy hauler (tongue weight 480) so open back space for packing. I'll be starting out with some small trips to test everything out with a light load. However I plan to take it back East from the West coast and had come up with about 1800 cargo including passengers. Your towing capacity belies the 6000/660 rated for the X5 - US Standards and sounds more like we should believe the European standards and w/more rigorous testing. I'm delighted to hear this!
 

·
Registered
Joined
·
1,414 Posts
Look for withidl posts on airsteam forum. He has been towing a heavy airstream with E53. Here is his post on xoutpost.


Re weigh distribution - I believe the OE E53 hitch had inserts which reinforced the hitch and provided additional touch points with unibody. Not sure if your Curt hitch has them. I reinforced my hitch - it is recommended with E70 hitch if you use weight distribution, due to long drop plates to the receiver. However, I know people who did not reinforce the hitch and are using WDH.

US towing specs are based on the specs of the hitch. The vehicle is rated to tow 7,700 lbs under TUV standards, which are more robust than anything used in the US.
 

·
Registered
Joined
·
6 Posts
Thanks for sending the link, I'll look forward to taking a look at it. This is all really great news about the capabilities of the X5! My Curt 13162 hitch is straight up, no extras. What I think I'm hearing is that you can add reinforcement to an existing hitch, is this correct?
 

·
Registered
Joined
·
1,414 Posts
Google "can am hitch reinforcement", choose images and you will have an idea about the reinforcement. Basically this is a metal strut between the receiver and the rear axle carrier. Andy Thomson at Can am is well known expert on towing and they set up thousands of German SUVs for towing.
 

·
Registered
Joined
·
6 Posts
I'll have a look at everything you sent, thanks so much for your help. The hitch is being installed today so not enough lead time to pull together the weight distribution system (I didn't even know about it until you told me), but sounds like it's something that can be added on if I find that I need it, or just want to have it for a better & safer towing experience. I lean towards the latter.
 

·
Registered
Joined
·
1,414 Posts
Sure, you can add weight distribution later.
 
  • Like
Reactions: missharron

·
Registered
Joined
·
8 Posts
Yes, mine is a 2015 diesel.
I have a 2012 X5 i35sport and it tows a Nucamp Tab 400 just fine. The only thing I would change is adding a 1 1/2 -2" lift kit to the X5. I like having a slightly higher profile. If any of you have suggestions on where to get one installed in Seattle or surrounding area, please let me know.
 

·
Registered
Joined
·
8 Posts
I'll have a look at everything you sent, thanks so much for your help. The hitch is being installed today so not enough lead time to pull together the weight distribution system (I didn't even know about it until you told me), but sounds like it's something that can be added on if I find that I need it, or just want to have it for a better & safer towing experience. I lean towards the latter.
you don't always need a weight distribution systems. I pull a 18
foot camper which is evenly distributed in terms of weight. I do use a sway bar when coming across the Interstate 8 from Austin to San Diego because the winds can get really bad and the sway keeps it perfectly behind the vehicle. Although I have never tried to tow in heavy winds without the sway bar......hmmmm- might just be my next project:)
 

·
Nuclear engineer
02/2012 X5 35d M57Y CPO 98K miles NOKIAN WR G3 12K miles
Joined
·
16,975 Posts
you don't always need a weight distribution systems. I pull a 18 foot camper which is evenly distributed in terms of weight. I do use a sway bar when coming across the Interstate 8 from Austin to San Diego because the winds can get really bad and the sway keeps it perfectly behind the vehicle. Although I have never tried to tow in heavy winds without the sway bar......hmmmm- might just be my next project:)
That is not the purpose or intend of a weight distribution system. A WDS is to distribute between tow vehicle front and rear suspension. A properly configured BMW Dynamic Stability Control will prevent sway.

All salesmen.com are liars interested in selling YOU their product and credibility.
 

·
Registered
Joined
·
1,414 Posts
Well, BMW DSC won't prevent sway in all cases. Maybe with a small trailer. Mabye... With my 33' I wouldn't rely on DSC.
 

·
Nuclear engineer
02/2012 X5 35d M57Y CPO 98K miles NOKIAN WR G3 12K miles
Joined
·
16,975 Posts
Well, BMW DSC won't prevent sway in all cases. Maybe with a small trailer. Mabye... With my 33' I wouldn't rely on DSC.
A properly configured BMW Dynamic Stability Control will prevent sway.
I am sure that you are right.
 
1 - 20 of 24 Posts
Top