Troubleshooting Trailer Turn Signals on 7-Way Both Having 12 Volts at all Times

Question:

I had a 7 way wiring kit installed professionally...I am noticing issues with my trailer lights being on at all times when connected to my van. I tested the wiring and found that in addition to the red 12v constant power, my green and yellow wires also have constant 12v. Did they mess something up with the install or could there be some other explanation for why these wires would have constant power?

asked by: Tom S

Expert Reply:

The stoplight and blinkers circuits should not have 12 volts of power on them at all times. Typically when what you described happens it's because the 12 volt power circuit is shorting out to those circuits. If you paid someone recently to install the 7-way I would take the vehicle back and have them fix it.

Another possibility is that the trailer wiring converter box that was used for the taillight circuits has shorted out due to a short on the trailer wiring.

What you will want to do is test the wires going into the box of the converter box for voltage with a circuit tester like the # PTW2993 to see if there is voltage going into the box when the taillight functions of your vehicle are applied, and then test the output side of the box to see if the current is making it through the converter. If not then the problem is that the converter box has shorted itself out and would need to be replaced.

Before you replace it you will want to inspect the wiring of your trailer to see if you can find anything that would cause the box to short out like corrosion or cut/exposed wiring. These boxes don't usually go out unless there is a short on the trailer that takes it out.

If there isn't input voltage for the converter then the problem is the wiring of the wiring kit. You will need to check to make sure it's making a solid connection to the correct circuits.

expert reply by: Jameson C