Installing Vehicle to Vehicle Tail Light Converter # 118158 on Trailer w/Separate Brake/Turn Lights

Updated 04/15/2013 | Published 04/11/2013

Question:

I want to connect a Mercedes Benz ML-350 using the factory trailer Socket to a German Spindelberger Cobra glider trailer separate yellow/red turn/stop I would like to assemble an adaptor mounted on the trailer tongue with a plug going to the car, and a recepticle for the trailer wiring plug using your 118158 adaptor. This will allow using the trailer behind other tow vehicles with the German recepticle and also behind the Mercedes without changing the recepticle or adding another recepticle to the Mercedes. I am a little confused by the diode discussion on your site, but do not think I would need these since there is no power source battery on the trailer. Is this correct? For reference Car socket has... Trailer Plug has... Positivedirect connect-Positive Negative-direct connect Negative -in to 118158 RH Stop/Turnin to 118158 118158 outRH Turn LH Stop/Turnin to 118158 118158 outLH Turn 118158 outStop LH/RH common circuit Backup Lamps-not used Running Lightsdirect connect -RH /LH tail lights Is this correct without using the diodes and do you see any issues?

asked by: John E

Expert Reply:

What the vehicle to vehicle (or vehicle to trailer in this case) does is to take the combined turn and brake signals on a vehicle trailer connector and separates them out so the turn signals and brake lights are separate. When using this converter on a trailer like you want to, you would not have to use diodes. I have included a picture that shows how it would wire up.

Essentially you would mount this converter on the trailer. The trailer would need a regular 4-Way flat connector like # HM48110. The yellow wire will go to the yellow on the converter and green would go to green. White will be grounded to white to the trailer frame. The brown wire bypasses the converter and goes on to the tail lights for the running light function.

On the output side, the yellow wire will now just carry the left turn signal. Green will have just right turn signal. And red will have just brake lights.

expert reply by: Michael H