Testing Trailer Wiring Converter Box to Determine if it is Damaged

Updated 11/12/2015 | Published 11/11/2015

Question:

I have a 2008 toyota highlander 4x4 with a Curt circuit protected tail light converter S0601. It has been on the vehicle for several years i didnt install it, but it looks like it was properly installed. It is a five wire to four wire converter but at the rear hatch a fifth trailer brake wire has been added. I am trying to connect it to a four wire trailer plug but am having difficulty with the right turn signal. Everything works fine when wired into the new four wire plug except the right turn signal. My multimeter shows a voltage change on the green wire left turn signal but no voltage change on the yellow wire right turn signal. It seems like the problem must be the tail light converter but I dont want to buy a replacement until I know for sure. Is there any way to test the converter itself? I have cleaned the ground on the right tail light.

asked by: Keith H

Expert Reply:

If the trailer wiring was working properly why do you need to run that additional wire to the converter? It sounds like that is the problem. Only one source for the right turn and stop light circuit is needed.

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 # 3808 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.

I attached a video that details how to do this as well.

expert reply by: Jameson C