How to Add a Back Up Circuit to a 4-Way Connector

Updated 05/30/2024 | Published 05/26/2024

Products Featured in This Question

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(83)

$22.91

12-10 Gauge Butt Connector

(23)

$0.86

12 Gauge Wire - Black Primary - Per Foot

(30)

$2.01

Hopkins Endurance 5-Way Flat Trailer Wiring Kit - Vehicle and Trailer Ends - Ergonomic Design

(37)

$22.59

Cordless Circuit Tester

(15)

$19.26

Quick Splices - Self-Stripping Connector - Closed Port - 10-12 Gauge - Yellow - Qty 1

(56)

$2.88

Question:

I have an 83 C10. I installed an online wiring harness that I got from NAPA but the backup lights no longer work. Will the backup lights still work with your connector? Jerry R

asked by: Jerry R

Expert Reply:

No, it will not because the T-One Vehicle Wiring Harness item # 118311 is a 4-way connector and those don't power the back up lights on a trailer. The one you bought online is probably functioning correctly.

The reverse lights on a trailer must receive power from the reverse lights on your C10. To do this, you will want to install a 5-pin connector on the trailer and on the tow vehicle. I recommend installing the Hopkins Endurance 5-way Flat Wiring Kit, item # HM47890. You can simply cut off the 4 pin connectors on your tow vehicle and trailer and splice in these 5-way connectors. You will need a total of 10 butt connectors, item # 05732-2, to splice the wires together.

Once you have the stop, turn, and tail light functions wired into these connectors, you will need an additional length of wire to reach the reverse lights from the 5-way connector on your trailer. I recommend purchasing an appropriate length of 12 gauge wire, item # 12-1-1.

The last step is to connect a wire from the vehicle side 5-way connector to the reverse light circuit on your C10. For this, you can use the same 12 gauge wire item # 12-1-1. To find the reverse light circuit, you will want to use a circuit tester like item # PTW2979 to probe the wires at one of your tail light assemblies. Once you find the wire that is hot when the reverse lights are on, you can splice in the 12 gauge wire using a quick splice like item # SWC501915-1.