Troubleshooting Curt Trailer Wiring Harness # C56175 in 2005 Mazda Miata

Question:

I installed a 56175 Taillight converter on a 2005 Mazda Miata. It installed easily and the running lights and brake lights work fine. The blinkers however will not work unless I remove the bulb and install it while the blinker is on. It acts as if removing and re-installing the bulb jump starts the blinker. If I run a 12V jumper directly to the trailer side wiring connector the blinker element works every time. I would appreciate any help with this. Thanks.

asked by: Russ W

Expert Reply:

The most common fix for a wiring harness that works fine on some functions but not others is to re-position the ground wire. A weak ground can cause lots of odd behavior, including some functions working while others do not.

Make sure the ground wire ring terminal is FIRMLY affixed to a clean bare metal surface on the car. You may need to sand off some paint or primer, clean off any grease or other foreign material, or you can relocate the ground terminal to a new position. Be careful when drilling that you do not damage any components behind the surface you're drilling into.

If this does not correct the problem then next check the condition of the wire splices into your Miata's wiring. The harness kit includes quick-splice connectors for convenience but a better and more reliable connection can be made with butt connectors like # DW05744-10. Use these to tap into each light circuit's wire.

If you are referring to a ground jumper wire then its almost a sure thing that a weak ground is the cause for the problem.

expert reply by: Adam R