How to Add Flat Tow Capable Wiring to a School Bus
Updated 02/16/2026 | Published 01/23/2026
Question:
I have a school bus that needs trailer wiring for flat towing a car. My bus currently does not have any trailer wiring. The bus’s brake lights and turn lights are separate wires. But the 7 and 4 pin vehicle side receptors that I see necessitate the turn lights and brake lights to be connected to same pin? Right turn/stop. Left turn/stop. I don’t plan to use any electric brakes, but just want towed car to have working brake, turn, running lights and a power line for charging the battery. Thanks for your help!
asked by: Tyler M
Expert Reply:
Hey Tyler, thanks for the information and welcome back. To add wiring to your school bus you'll need to install the Tekonsha Tail Light Converter with 4-Way Flat Trailer Connector item # 119178KIT. This kit includes the powered converter, a circuit tester to help you identify the wires for connection and the quick-splice fasteners.
The converter included with the Tekonsha item # 119178KIT will combine the separate stop and turn functions on the 4-pole output side. These combined signals will be carried on the green and yellow wires, right and left respectively.
You can then install the Adapter 4-Pole to 7-Pole and 4-Pole item # 37185. You'll plug the 4-way directly into it from the item # 119178KIT. You'll then need to install the Roadmaster Battery Charge Line Kit for Motorhomes item # RM-156-75. This will connect directly to your bus's battery and connect to the 12v circuit on the 7-way.
These two harnesses will allow you to control your flat tows wiring functions and power a charge line.
What vehicle are you setting up to flat tow and do you need recommendations on parts?
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Tom F.
2/16/2026
The expert reply by Jerred H pretty much says it all really well. I installed the parts referenced on a 2006 Jetta, for towing a small home build trailer. Since I am not too good with electronics, I just watched the installation videos on etrailer concerning the parts I purchased, and followed the installation instructions. Everything worked perfectly. For technical support, I would refer you to etrailer. Their techs are really good. Tom