Wiring 7-way trailer hitch harness for electric brakes. Possible for e90?

E91 Hoarder · 03-10-2024, 12:05 AM

Is it possible to wire 7-way hitch harness instead of just 4-way?

I have a teardrop camper trailer with electric brakes and would like to pull it with my e91 and utilize the trailer brakes. It is light enough to be pulled by this car.

Did my research, but could not find any hitch wiring harness retrofits. I understand that 3-series was never intended as tow vehicle for the US market, and we are supposed to tow with SUVS here, but I digress.

How to install a 7-way hitch connector and wire it in the car? Any ideas/suggestions?

E91 Hoarder · 03-11-2024, 01:36 PM

Anyone? Maybe our EU friends can chime in?

Brian86 · 03-11-2024, 11:37 PM

e9x are almost certainly not pre-wired for trailer brakes. (correct me if I'm wrong)

You'll need to run your own power supply and wires for a brake controller. I like the tekonsha inertial controllers.

Then start splicing and wiring. It'll need about a 30 amp constant +12 supply, an input from the brake pedal switch, and an output to the brake lights. Run the brake +DC to the rear of the car.

The car's harness should handle lighting. You'll also need to splice perhaps 5 amps of ignition +12 to charge the breakaway battery on the trailer.

03-10-2024, 12:05 AM	#1
E91 Hoarder Captain 126 Rep 852 Posts Drives: E91 AWD, E91 RWD, E90, X535i Join Date: Oct 2011 Location: On the Road iTrader: (8)	Wiring 7-way trailer hitch harness for electric brakes. Possible for e90? Is it possible to wire 7-way hitch harness instead of just 4-way? I have a teardrop camper trailer with electric brakes and would like to pull it with my e91 and utilize the trailer brakes. It is light enough to be pulled by this car. Did my research, but could not find any hitch wiring harness retrofits. I understand that 3-series was never intended as tow vehicle for the US market, and we are supposed to tow with SUVS here, but I digress. How to install a 7-way hitch connector and wire it in the car? Any ideas/suggestions? __________________ "Let me see what I can do... sir"
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03-11-2024, 01:36 PM	#2
E91 Hoarder Captain 126 Rep 852 Posts Drives: E91 AWD, E91 RWD, E90, X535i Join Date: Oct 2011 Location: On the Road iTrader: (8)	Anyone? Maybe our EU friends can chime in? __________________ "Let me see what I can do... sir"
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03-11-2024, 11:37 PM	#3
Brian86 Captain 640 Rep 769 Posts Drives: e36 M3, e91 325xi, N50 Xterra Join Date: Dec 2020 Location: Pittsburgh iTrader: (0)	e9x are almost certainly not pre-wired for trailer brakes. (correct me if I'm wrong) You'll need to run your own power supply and wires for a brake controller. I like the tekonsha inertial controllers. Then start splicing and wiring. It'll need about a 30 amp constant +12 supply, an input from the brake pedal switch, and an output to the brake lights. Run the brake +DC to the rear of the car. The car's harness should handle lighting. You'll also need to splice perhaps 5 amps of ignition +12 to charge the breakaway battery on the trailer. __________________ Sometimes a bolt is just a bolt.
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