Installing Reverse Lights on Trailer Using 7-Way Connector and Wishbone 4-Way Wiring Harness

Updated 03/14/2019 | Published 03/13/2019

Products Featured in This Question

Mighty Cord 4-Way Flat Trailer Connector - Wishbone Style - Trailer End - 25' Long

(43)

$24.89

16 Gauge Primary Wire - Black - Per Foot

(61)

$1.14

Mighty Cord 7-Way RV-Style Trailer Connector w/ Molded Cable - Trailer End - 10' Long

(82)

$49.81

2-Wire Pigtail for Optronics Backup and Utility Trailer Lights - 2-Prong PL-3 Plug

(119)

$5.50

PVC Grommet for 6-1/2" Oval Trailer Tail Lights

(966)

$4.69

GloLight LED Backup Light for Truck or Trailer - Submersible - 22 Diodes - Clear Lens

(134)

$33.71

Deka Heat Shrink Butt Connector - 16-14 Gauge - Nylon Insulation - Blue - Qty 10

(1104)

$13.84

Deka Heat Shrink Butt Connector - 12-10 Gauge - Nylon Insulation - Yellow - Qty 10

(1104)

$13.82

Question:

My trailer is a flat bed utility trailer that has electric brakes,and break away attachment. The wires coming from those braking features are either black or white no blue. I am also installing backup/reverse tail lights instead of the normal simple brake and turn signal lights, so how do I come up with a purple wire to attach to my 7 way plug as well as connect the correct brake wire blue to the correct wire from my plug. The trailer was originally wired using a 7 way plug but utilizing only 5 wires, so I am replacing the trailer 7 way plug. The parts I’m using are in the image provided. Thanks,

asked by: Trapr S

Expert Reply:

Using the Mighty Cord Wishbone 4-Way Flat Trailer Connector - Trailer End - 25' # A10-4225VP will give you the wiring for the tail lights on each side of your trailer giving you both the running light for each side and then the stop/turn function for each side. The ground wire will connect to your trailer frame on a bare metal to metal surface.

Then when using the Mighty Cord 7-Way RV-Style Trailer Connector w/ Molded Cable - Trailer End - 10' Long # A10-7W10 or similar based on length, you will connect the wishbone harness in the following ways.

Yellow: auxiliary and reverse lights will allow you to run two wires # 16-1-1 to your tail light pigtail # A45CB red wire. The white wire with the ring terminal will ground to your trailer frame. Then the pigtail will connect to the light # BUL111CB which uses grommet # A70GB.
Green: tail lights will connect to the two brown wires on your wishbone harness.
Brown: right turn and brake lights will connect to the green wire on your wishbone harness
Blue: electric brakes will route to one side of each brake magnet and the other brake magnet wire will be attached to the frame bare metal to metal.
Black: 12V battery charge will connect to the positive battery terminal of your trailer battery..
Red: left turn and brake lights will connect to the yellow wire on your wishbone harness.
White: ground to your trailer frame bare metal to metal.

For your connections you can use # DW05744-10 and # DW05745-10.

On the vehicle if you have a purple wire on your 7-way that will connect to the reverse light power wire at your tail light if not already connected. Some companies use purple wire and others yellow and you can see from the paragraph above that colors and functions don't always follow the same standard.

I've attached a trailer wiring article to help further if needed.