How to Connect Trailer wiring for 2013 BMW X3

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Question:

Hi. My BMW has one wire driving the tail and brake bulb. The signal is a separate wire. Both bulbs are 1156 style. However, the tail/brake bulb draws 4 volts for tail, then 12 volts for brake. The 1156 bulb is a single pole/filament style. Will the flat 4 wire harness work? If not, what do you recommend? Thanks.

asked by: Richard

1

Helpful Expert Reply:

Your 2013 BMW X3 has a Pulse Width Modulation Stop/Tail (PWM ST) wiring systems, sometimes called Multiplex wiring. The Curt Powered Tail Light Converter with 4-Pole Flat Trailer Connector # C59236 will work with your X3, but it has to be installed a certain way for all the lights to function properly. Since you already have done some testing and identified what kind of system you have it will be easier and quicker to get installed.

You need to test and identify the color of wires for each function on your X3, stop, turn, and tail. There are 5 wires that come out of the converter box in the wiring kit, and they should be hooked up as follows :

Green wire - splices into right turn signal wire
Red wire - splices into stop/tail signal wire
Yellow wire - splices to left turn wire
White wire - connects to vehicle ground
Brown wire - Not used (or grounded with white wire)

I prefer to not use the quick splice connectors in the kit and use Deka Butt Connector # 05731-5 anytime that I have to splice any wires. It provides better protection for the wires and is more secure.

One big advantage to installing wiring in your BMW is that the battery is in the rear hatch; so routing the power wire from the converter box to the battery will be much easier than if it were under the hood.

I linked a video of the wiring install on a different year X3 but the process will be similar. I also attached a copy of the instructions showing you how to hook up the wiring for each type of system it works with.

expert reply by: Robert C

1

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Richard

2/21/2020

Will the CURT trailer module fool the CANbus system on the BMW X3 ?Thank you.

Chris R.

2/23/2020

The Curt harness won't affect the CAN bus system on your BMW in any way. All vehicle functions will continue like normal with the trailer wiring installed.

Answer 1

I recommend using the Tekonsha ZCI Circuit Protected Vehicle Wiring Harness #119250KIT for your 2013 BMW X3 as this kit does not require you to splice into any of your wiring. There are several 5 star reviews from our customers installing this kit on…

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Answer 2

When installing the Curt Trailer Hitch Receiver #C13420 on a 2020 Kia Telluride you do have to remove the spare tire; that is the first step but it does get put back into place at the end of the installation. The install of this hitch is relatively…

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Answer 3

Congrats on the new SUV. To add a hitch to your 2023 Kia Telluride, I recommend the Curt Trailer Hitch item #C13420. This hitch is custom fit and bolts to your Kia with included hardware. This is a class III hitch with a 2" receiver. It has a…

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Answer 4

I would be happy to! To add a hitch to your 2024 Kia Telluride, I recommend the etrailer item #e45ZR. This hitch is custom fit and bolts to your Kia with included hardware. I really like this hitch because the crosstube mounts behind your rear bumper…

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Answer 5

Hey Thomas thanks for your question. The Curt Trailer Hitch #C13420 does not require the rear power latch to be replaced. We have done several installs on Telluride models 2020-2024 and a latch replacement has never been needed. I even double checked…

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Answer 6

The difference between the Class II and Class III hitches has to do with their Gross Trailer Weight (GTW), their Tongue Weight (TW), and their Hitch Receiver Size. Class II trailer hitch receivers have a 1-1/4 inch receiver and can be rated up to…

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Answer 7

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Answer 8

Hey Wanda, thanks for reaching out. We have just the thing! To connect your Roadmaster EZ Base Plate Kit #521877-1 to a tow bar you will need the following: - Replacement Quick Disconnect Crossbar Assembly for Roadmaster Tow Bars #910021-00 This will…

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Answer 9

Hey Gary, thanks for reaching out! I recommend picking up the Curt Vehicle Wiring Harness #C59236 for your 2026 Kia Sportage. It splices into the tail lights of your vehicle and then draws power straight from your battery so it's completely…

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Answer 10

Hey Pete! For a hitch I recommend our own etrailer Trailer Hitch #e59ZV. This is a Class III hitch with a 2" receiver and a matte black finish. For custom wiring you can use the Curt T-Connector Vehicle Wiring Harness #C93DQ. This plugs in…

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Answer 11

Hey Todd, congrats on the new SUV. To add a class III hitch to your 2026 Toyota Grand Highlander, I recommend our etrailer item #e69ZV. This hitch is custom fit and bolts to your Toyota with included hardware. It has a 5,000 lbs towing capacity and a…

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Answer 12

Hey Robert! Thanks for reaching out. We do have a wiring harness available for your vehicle! It's the Curt Powered Tail Light Converter #C59236. I recommend the etrailer Trailer Hitch Receiver #e66ZV, it's the easiest to install plus it has a…

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How to Connect Trailer wiring for 2013 BMW X3

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