Is there a European 7-Way to US 4-Way Trailer Wiring Adapter for a BMW

Updated 03/02/2012 | Published 02/28/2012

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Question:

I have a BMW with a 7pin 12N Euro towing adapter. The wiring is such that it works with the cars computer. I am in the USA and want to be able to use the standard USA 4 pole wiring with this setup. Any suggestions? I dont want to install any new wiring inside of the car. Hoping to convert this with an adapter or through some minor wiring outside of the car. My understanding is the 7 pin 12n adapters wiring is: 1. Left hand turn signal 2. Fog lights 3. Ground 4. Right hand turn signal 5. Right hand tail lights 6. Brake light 7. Left hand tail lights The USA wiring is White - Ground Green - Right hand turn signal and stop Yellow - Left hand turn signal and stop Black - Running lights Seems like I could take a 4 pole and connect 1 to Green left hand turn signal 2 Ignore 3 to ground 5 and 7 directly to Black running lights 4 to yellow right hand turn signal But I dont know how to incorporate the brake lights 6. Any help would be greatly appreciated. Thanks

asked by: Jim

Expert Reply:

Bascially, there is no easy way to convert the European 7-Way to a US 4-Way. We do not carry any kind of adapter that you could use. You are left with 2 options. First, you would install a separate wiring harness which would be the easiest. Or, you could attempt to fabricate an adapter.

You would need to use a converter, # RM-732. The red wire on the input side would attach to the brake light wire on the vehicle wiring. The white wire grounds to the frame. The yellow wire will attach to the left turn signal wire on the vehicle. The green wire will attach to right turn signal.

The out put side only has 2 wires. Yellow, which will be combined left turn and brake, and green for combined right turn and brake. To get the running lights, attach a wire to either running light circuit on the vehicle trailer wiring, and route the other end of the wire directly to a 4-Way vehicle side connector like # 18002.

You probably will not need the whole 60 inches on the 18002 harness so clip off he excess wire as needed. The yellow and green wires on the converter out put side will match the yellow and green on the 4-Way. The running light wire you ran goes to the brown wire. Ground the white wire directly to the frame.

This should give you the function you need but it should only be used as a temporary solution. The best way to add a 4-Way US style trailer connector is to have it installed in addition to the connector you already have.

expert reply by: Michael H