What Should the Voltage Output Be at the 4-Way Plug on Curt T-Connector Wiring Harness # 56016
Updated 07/07/2025 | Published 04/10/2011
Question:
I recently installed a Curt 56016 powered trailer harness and went to check the 4 pin plug with a voltmeter. It is reading 12 volts on all 3 pins witout the lights even on. I assume I have a bad harness that is somehow shorted out. I was wondering if the the harness should read 12 volts on the black wire only when the the tail lights are on? And then 12 volts flashing in and off for the left and right turn signal. This is how I think it should work logically. I just want to make sure that I have a faulty harness before I send it back. Thank You
asked by: Blake H
Expert Reply:
When you test the 4-Way on the Curt T-Connector Wiring Harness, part # 56016, at the rear of your vehicle, it should show now power on all 3 pins with the lights off. If you have the vehicle head lights on, you should have around 12 volts at the brown (tail lights) pin only. If you apply the brakes, you will have about 12 volts at the green (right turn and brake) and yellow (left turn and brake) pin with the head lights off. If you turn on the right turn signal, you will have around 12 volts flashing at the green pin only and if you turn on the left turn signal you will have around 12 volts flashing at the yellow pin only.
The black power wire should show 12 volts all the time, as long as the fuse in the fuse holder is good.
You will also want to make sure you have the white ground wire on the wiring harness connected to a good, clean ground.
I am including a link to a FAQ page on trailer wiring and it will describe how to troubleshoot your trailer wiring.
Dylan J.
7/7/2025
So how many volts should be going to the dome light switch on a reefer unit trailer I’m getting .7 Volts as a reference and the only fuse box that im aware this trailer is is for the reefer unit
Jameson C.
7/7/2025
Product Page this Question was Asked From
Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- Vehicle End Connector
- Powered Converter
- No Tow Package
- 4 Flat
- Plug and Lead
- Plug-In
- Hidden
- CURT
more information >
Featured Help Information
Instructions
Miscellaneous Media
Continue Researching
- Shop: Trailer Wiring
- Shop: Trailer Hitch
- Search Results: seal cross reference
- Search Results: flat tow wiring harness
- Search Results: curt t~connector vehicle wiring harness with 4~pole flat trailer conne
- Search Results: ez connector flat tow wiring harness
- Search Results: ball mount rise
- Search Results: rv bidet
- Shop: Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Article: Trailer Wiring Diagrams
- Search Results: 2" ball mount
- Shop: Base Plate for Tow Bar
- Shop: Vehicle Tow Bar Brake System
- Shop: Curt Custom Base Plate Kit - Removable Arms
- Shop: Blue Ox Patriot Portable Flat Tow Brake System - Proportional
- Shop: Curt Trailer Hitch Receiver - Custom Fit - Class III - 2"
- Shop: Vehicle Tow Bar Wiring
- Shop: Curt Trailer Hitch Receiver - Custom Fit - Class III - 2"
- Video: Feature Review Curt T-Connector Vehicle Wiring Harness for Factory Tow Package-C55260
- Q&A: J-Case Fuse Position For Curt 7-Way Harness On 2024 Honda Pilot Blocked
- Shop: Thetford Aqua-Magic Residence RV Toilet - Standard Height - White Polypropylene
- Shop: Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Article: Wiring Trailer Lights with a 4-Way Plug (It's Easier Than You Think)
- Shop: Roof Rack
- Shop: Brake Controller
- Video: Setting up the etrailer XHD Non-Binding Tow Bar for Blue Ox and Curt Base Plates on a 1989 Jeep YJ
- Video: Setting up the Blue Ox Base Plate Kit on your 2021 Jeep Cherokee
- Video: An In-Depth Look at the Roadmaster Battery Charge Line Kit for Towed Vehicles
- Q&A: LED Indicator Stays On All the Time When Trailer is Plugged Into 7 to 4-Way Adapter 47345
- Video: Breaking Down the K-Source Universal Towing Mirror
on Custom Fit Vehicle Wiring
Keith
6/11/2025
Would the testing be the same for wiring harness #56395?