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.
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 >
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Keith
6/11/2025
Would the testing be the same for wiring harness #56395?