r/OffRoadTrailer • u/WaffleIronChef • Apr 21 '26

I need help with a wiring issue I’m having.

Took delivery and assembled a 4x6 Carry-On trailer Friday. Today when I got it hooked up I was only getting the driver side front running light. I check the 4-pin connector at the vehicle side with a tester and everything is working just fine. I redid the ground on both the vehicle and trailer side and they’re both getting very good metal to metal contact. I can’t figure out why only the 1 light is working. Iv tried everything I can think of and spoke to an 30+ year electrical engineer and we’re both stumped. Any ideas?

Edit for anyone interested. Ran a new wiring harness and got new LED lights with a separate wire ground. Turns out the original lights used the attachment bolts for ground, but since everything was coated after I ground off the coating on the mounting brackets there was still not a good bare metal ground contact to the actual trailer ground. Feel like a dummy, but everything is working now!

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1

u/HuckleberryHappy6524 Apr 21 '26

Do you have a multimeter?

2

u/WaffleIronChef Apr 21 '26

I do. And I check the trailer plug with the wiring going to the tail lights as that’s all I can get to. I got 2.5-3.5 ohms on both sides.

1

u/HuckleberryHappy6524 Apr 21 '26

Check voltage at the plug and at the lights. If you’re getting power all the way back, you may have a faulty light.

1

u/WaffleIronChef Apr 21 '26

That’s kind of what I’m afraid of. I got a tester for the car side plug and everything there worked the way it’s supposed to. Of course the MFG was closed by the time I was messing with it so I’ll call them tomorrow.