Troubleshooting Trailer Wiring 4-Way that Has Voltage on All Pins

Products Featured in This Question

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

(312)

$75.20

Hook Probe Circuit Tester

(55)

$11.68

Question:

Hi, I bought item C56164 back in April and was able to follow your instructions on installation. It went fairly smoothly and everything seemed to work I also bought item 86065 hitch cover as something to light. I noticed that the LED would stay lit very dimly even when the vehicle was off. I figured and your QandA confirmed that it was simply the low draw of an LED still being lit from the current in the system. However about a month ago, I noticed that the hitch cover was lit like the breaks were applied even when the vehicle was off. I would shake the wire harness and sometimes, it would go back to simply dimly lit. Now, no matter what I do, the hitch cover is lit up all the time. I have done a voltage test and all three of the wires are pulling over 12 volts even when the vehicle is off. Just to make sure that it was the wire harness that was bad, I have plugged in another light up hitch cover and a jet ski trailer. It is doing the same thing to all three. What was interesting on the trailer was the lights were always fully lit when the car was on and off. The light corresponding to the turn single that was activated would blink while the other one was fully lit but neither would blink when the hazards were initiated. I have tried resettinginch the control box by removing the fuse like in another QandA, which has not worked. The ground seems secure and the wires look like they are all in good condition. Im at a loss on what could be bad other than the control box itself. Any help would be appreciated. Thanks.

asked by: Mike

Expert Reply:

It really sounds like the converter box of the # C56164 has shorted out. You can test this to be sure though.

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