Troubleshooting Trailer Wiring Install that Shows No Blinkers but Other Circuits are Active

Question:

Installed this 56175 wiring kit onto my 2000 Mazda Miata. Install went fine. When complete I ran a test light probe into each of the outbound harness connectors, and all worked fine - tail, brake, left turn, right turn. When I hook it up to the trailer, I only have brake and tail lights - no left or right turn signals, and no emergency flashers. Knowing the installed harness tested fine, I assumed a problem with the new trailer usually a bad ground. So I hooked the trailer up to my Ford Explorer, and all functions work fine. That eliminated trailer wiring problems. It seems to me that the issue is with the in-line module included in the wiring kit. Need some help, please. Fyi, its a very small trailer, obviously towing behind a Miata, that is just big enough to carry four tires/wheels to the track. Trailer lighting is only standard left and right tail lights and one side marker on each side. Thanks,

asked by: Mike J

Expert Reply:

If you test the pins of the 4-way right now do they flash with the blinkers? It's bizzare that the higher drawing circuits of stop and running lights would work but the blinkers would not. Typically that's a converter box issue so let me know if those circuits test positive with a tester. If not test the input side of the box too to see if the correct voltage is making it into the box. If not, then the issue is connections.

expert reply by: Jameson C