BMW 1 Series Coupe Forum / 1 Series Convertible Forum (1M / tii / 135i / 128i / Coupe / Cabrio / Hatchback) (BMW E82 E88 128i 130i 135i)
 





 

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      07-10-2016, 11:39 AM   #177
odj
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Hi All -

I installed a hitch and wiring harness adapter on my 2013 135is yesterday and figured I'd share my experience since I see a lot of the same questions being asked.

I picked up a Curt C111841 (which includes a 1 7/8" euro drawbar) and a Tekonsha Modulite ZCI harness adapter. I picked up the latter since it required no splicing (and should result in no light errors).

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Hitch install is just like it says in the directions included with the Curt. Remove the bumper fascia and the plastic undertray thing on the passenger side. The hitch slides right over the bumper bolts with everything else in place.

These are all the tools I used for the install. Well, plus a sharpie and a razor knife.



The exhaust bracket (this is the PE, mind you) was ~1/16" from the hitch bar. This is the view looking up from the ground.



So I marked and cut the bracket.





Cut out the plastic like it says (I had to cut further down in the center section)..



And it fits right in there.



Bam.



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Here's the ZCI harness kit:



It has inductive sensors which snap around the wire.

I started by pulling off the trunk liners, and under the right side carpet is a molded foam support which had an existing electronic module in it, and a slot that perfectly fit the ZCI control module.

I wired everything up using mostly signals from the right side harness, with the exception of the left turn signal. The inductive sensors are slightly bulky, so the challenge was finding locations for them where they wouldn't rub or be crushed in normal use of the car.

Here's the right side...





... and the left side.



Not my cleanest wiring work ever, but it's tested and fully functional.

There's a main chassis ground right near the right tail light, so I used that to ground the ZCI unit, and ran power to the trunk (orange wire in the top right of the following photo). The trailer harness just hangs out in the battery compartment.



And will hang out of the trunk when in use.



I'm not super happy about having it hanging out of the trunk, but I didn't feel like taking the bumper off yesterday. it was ridiculously hot. Maybe that's a project for another time.
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      08-27-2016, 10:04 AM   #178
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Quote:
Originally Posted by Trenchdigger View Post
Update: Yes, it is Curt #11184

I installed it on Sunday. Fits great, no issues on a 2013 128i. I'm using it for a bike rack; plenty of clearance.

Note: I did NOT remove the bumper cover to install. However, it would have been much easier if I had.
Trenchdigger, can you confirm that no trimming was required on your 128i? Did you have any muffler rattling noise after the exhaust gets hot? I am about to start an install on my 2012 128i SULEV 'vert.
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      01-13-2017, 02:06 PM   #179
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Reviving an old thread. Do you know the wire coloring which connects to what?
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      02-06-2017, 02:19 PM   #180
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Quote:
Originally Posted by 1hot135I View Post
Reviving an old thread. Do you know the wire coloring which connects to what?
I just did this whole job on my 2012 128i, installing the trailer hitch and adding the ZCI wiring harness. It was all really easy with the exception of removing the bumper cover. All the obvious and visible bolts aside, the key to getting the bumper cover off is to remember the bolt that is buried beneath the felt near the top of the wheel wells. With the bumper cover off, the hitch took under 5 minutes to put in to place and torque down to spec. I didn't need to lower the exhaust -- maybe that step only applies to the 135i?

For my vehicle the wire colors are as follows (applies to both left and right sides):

Blue/Gray: Turn signal (left side is left turn signal, right is right, of course)
Yellow/Green: Tail light
I seem to have lost my notes about which one corresponds to the brake light, but I think it's yellow/gray.
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      12-18-2017, 02:52 PM   #181
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My son and I put the Curtis hitch and a Curtis relay box for the lights on my 128i convertible Saturday. Took us about 5 hours but mostly it was him working and me talking. I used it to tow my utility trailer to the dump Sunday. The European tow bar seems a bit low but everything went well. I used this DIY and it helped. Car barely noticed the trailer. My trailer is a 4x8 from Harbor Freight that is only rated for 1100 lbs. I usually have a lot less on it. I think the bimmer will be fine. We left the plate off that is under the car that you have to cut for the hitch. You can't see the opening unless you go under the car. Wiring is soldered on - that took a little more time but will not turn into an issue later. My wiring comes out the trunk like is illustrated above. I have not done it this way on other cars but if you go under the bumper cover, your wiring mount would be pretty low and a bit of a hassle to use. With the soft weatherstripping on our trunks, having it come out like this is not bad. I decided I need a 5 inch rise for my utility trailer to sit flat. Tallest european mount seems to be just over 3 inches. So I bought a U. S. style bar, Curtis, and ball. Should arrive tomorrow.

Last edited by JimD; 12-19-2017 at 03:07 PM..
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      02-23-2018, 07:13 AM   #182
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Thanks a lot! Used this to do my install. Much appreciated.
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      03-02-2019, 03:28 PM   #183
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I installed my hitch and wiring today. It was pretty easy, even though the 128I requires the bumper cover to come off.

The center belly panel came off first, then the right side one. I left off the center when I put it back together. The bumper cover came off pretty easy. Remove all the bolts, then pull directly back on the bumper and the side clips come off pretty easily.





Then I temporarily installed the hitch. The clearance looked pretty good, but I did not want to do this twice, so I cat the exhaust mount as advised.







Tons of clearance now, and enough of the mount left to still be strong. I radiused the corner of the cut to reduce the chance of cracking.

Next the wiring kit.

I borrowed this from a member early in the thread, and use the Modulite 119147: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Left side of the car in multibulb assembly wires:
MODULITE ----------------------------------------------135i
LEFT TURN -------------------------------------- Blue wire with green stripe
BRAKES ----------------------------------------- Purple with Yellow stripe

Left side of the car on Tail light bulb harness:
TAIL LIGHTS ------------------------------------ Purple wire with Light Blue stripe

Right side of the car in multibulb assembly:
RIGHT TURN ------------------------------------- Blue wire with Brown stripe

Wire colors were fine for the 128i, and I used Posi-Taps instead of the supplied crappy crimp splices.








I will use this to tow very occasionally, so I elected to keep the trailer connector in the trunk. I will hang it out when I tow. Mostly it will be used for a bicycle rack. I tested the wiring with a trailer wiring tester and it worked perfectly.

It fit nice, and is a clean look.


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      07-09-2019, 01:00 PM   #184
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Trailer hitch Wiring harness for 2009 X5 35d

I have an emergency situation and am moving as fast as possible.

I purchased a curt class III hitch a while back. Did a lot of research on forums and found an after market wiring harness. My ex lost the harness and now I can't find that forum discussion.

I installed the hitch myself the other night to move a few things locally. Moving cross country in the next week and need to install a wiring harness ASAP.

Anyone have recommendations for a wiring harness that won't screw with my computer?

The one I purchased was around $60 from pep boys. It was an easy plug in.

I have a 2009 X5 35d XDrive with 180,000 miles on it.

Any tips or important info would be really appreciated. My stress level is almost in overdrive!

I checked all my hoses, changed the oil, doing breaks as we speak. Taking it in for transmission and cooling flush tomorrow. I think that lost wiring harness is my only hang up left.

Wiring harness?
Am I forgetting anything?

Thanks!
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      07-10-2019, 05:47 PM   #185
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Quote:
Originally Posted by DieselDoll View Post
I have an emergency situation and am moving as fast as possible.

I purchased a curt class III hitch a while back. Did a lot of research on forums and found an after market wiring harness. My ex lost the harness and now I can't find that forum discussion.

I installed the hitch myself the other night to move a few things locally. Moving cross country in the next week and need to install a wiring harness ASAP.

Anyone have recommendations for a wiring harness that won't screw with my computer?

The one I purchased was around $60 from pep boys. It was an easy plug in.

I have a 2009 X5 35d XDrive with 180,000 miles on it.

Any tips or important info would be really appreciated. My stress level is almost in overdrive!

I checked all my hoses, changed the oil, doing breaks as we speak. Taking it in for transmission and cooling flush tomorrow. I think that lost wiring harness is my only hang up left.

Wiring harness?
Am I forgetting anything?

Thanks!
It sounds like the ZCI one mentioned above is a popular choice.
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      07-11-2019, 10:15 AM   #186
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You minimize your potential for issues by using a powered converter - one that has connections for power to the battery - instead of one that just taps the power going to the car's lights. Other than that, I don't think it matters exactly what one you use. My car did not give me a "bulb is out" warning for a long time after I installed the hitch wiring but I have one now and can't find any bulbs out. So I think it still can happen.

But the bulb out is one ding and a warning light at startup, nothing more. I think that is worst case for what can happen with the wiring assuming you tap the right wires.

I don't have one but you can also buy a little tester you plug into the car side of the flat four connector to check the wiring without plugging in the trailer and walking around to be sure everything is working.

I thought it was far easier to do the wiring than install the hitch. Pulling off the bumper cover is a bit of a pain.
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      02-11-2024, 03:21 PM   #187
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I installed the Curt 111843 hitch on my 2012 135i. The 3 on the end of the model number just means it comes with a ball mount, pin and clip. Otherwise the hitch is the same as the Curt 11184. For some reason, Curt says it only fits up to 2011, but it fit my 2012 fine.

Installation was pretty easy. On M Sport models, you can get away with just removing the lower gray bumper fascia. Just remove the screws and pull down and out near the tabs to remove it. To put it back give it a good whack with your palm. Also I just left off the center lower plastic panel entirely so I didn't have to trim it.

[Edit] I went back and trimmed the under bumper panel as shown in the last pic.

I didn't trim the exhaust hanger, but I will if I notice any rubbing.

I haven't done any wiring because I just intend to use the hitch with a cargo carrier and bike rack for now. For the cargo carrier, I got a 1.25" to 2" receiver adapter with 4" rise, otherwise I think it would sit too low and scrape on inclines.
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Last edited by Stubbie Blue; 03-12-2024 at 10:41 AM..
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