Wiring harness troubleshoot.

In the process of installing two led lights on the bed of my truck. Bought a harness from Amazon built by rigid industries specifically for these lights. Everything is basically on the truck, just not plugged into the battery. When both lights are connected, the fuse blows out. When only one is connected everything seems to work fine. Wire is 18 gauge, with a 15A fuse like I said built specifically for these lights. Aside from a possible short, what other things should I be looking at.

 

For one if those are Rigid d2s a 15 amp fuse is overkill and doing you no favors. They apparently only draw 2.5 amps a piece/5 amps together according to Rigid. For perspective I run a 20 amp fuse for my 42" LED bar and really that's a little over what it should be.

I'm no wiring expert so maybe someone else will chime in but some things to think about:
1. Are you using the crappy switch that came with the harness? (3 position red button toggle switch)

2. Are the wires to th switch/battery/ground hooked up properly?

3. Where did you source the harness? If the answer is "Amazon" sometimes things are marked as made by rigid when I'm fact you get shipped a Chinese knockoff, not that it probably matters as I'm sure the legit Rigid stuff comes from the same place lol. To put it in perspective I've bought 2 "Rigid" harnesses from Amazon and they've had their suspicious differences

Otherwise I'd start tracing wires.

 

When you say with one connected everything is fine does that mean that you hooked up #1 ran it, then disconnected it and then ran #2? I just want to confirm that maybe one of them isn't shorting out.

 

Ran out of daylight yesterday, about to get home and try each one individually. I was also thinking about a different switch, I'll see if I can get them working today. Hopefully I don't have to trace wires, should've tried everything out before putting it on the truck.

 

Ok pulled the whole harness out, wired each light individually and each on their own worked fine. Everything seems fine, except when both lights are plugged in it burns the fuse. Maybe the harness is too long? Don't know if that's possible since light are only about halfway on the bed. About to give up on this harness and order a different one.