Troubleshooting Trailer Wiring 4-Way that Running Light Circuit is Active all the Time

Question:

Dear Sir, I have a 2006 Toyota Highlander Hybrid Limited. I am using a flat 4 connection While preparing my utility trailer for another season of hauling I came across a couple lighting problems. I discovered that neither of my LED taillights were working. I cleaned up the indivual ground for each of the lights and presto they worked. Now my driverside taillight is always on, even when the engine is off and keyes removed. I have tested the vehicle side of the connection and the brown wire terminal always has powere while none of the other terminal are hot. I disconnected the convertor for an hour hoping this might reset an internal connrction, no luck. The ground coming off the converter is clean as a whistle. I used a simple test lamp for verifiying connection. Any thought? the converter is 8 years old, has it gone bad? I attaches to my vehichicle via a connector ie wiring harness Thank you for any help you can give

asked by: Tony M

Expert Reply:

What you described sounds like a shorted out converter box. Here is how you can test 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.

For a new 4-way harness you would want the part # 118248.

expert reply by: Jameson C