Need some help with my non-functioning brake light splice

Thought I'd learn how to splice and solder to wire in a 3rd brake light. Turns out I'm having to learn more than I expected.

I cut and spliced into the 1st and 3rd position wires on the middle tail light plug and soldered them together. I know nothing about electronics or soldering, so I'm not sure if I soldered poorly or what. The driver side brake light still works, however the LED 3rd brake light and the passenger brake light do not work. I measured the voltages at both brake lights with my multimeter and I was still getting 12 volts on the passenger side, but nothing on the 3rd brake light. Kind of frustrated I didn't just use a quick tap or something at this point. Anybody got some suggestions for troubleshooting?

 

Solved it... crap quality light bar from China didn’t work and coincidentally the passenger brake light bulb also died. All is good in the world.

 

I'm glad you tracked down the problem, and I hope you're going to insulate that soldered splice with something. The problem is, due to the way you joined, then soldered it, it's going to be a bear to insulate properly. Personally, I think I'd re-do the whole splice properly. Although I know I'm going to get fried for this, I wouldn't solder it. Did you know that exactly none of the wire connections in your truck are soldered? All crimped.

 

Oh really, that is pretty surprising to hear. Initially I was going to use one of the sealed t-taps, but I saw a bunch of people saying how its better to solder it because it's stronger. As far as properly joining the wire, do you have a suggestion to make it easier to insulate?

 

Solder - properly done - is stronger. But how much force is that splice going to be under? Not much I would guess.

As for how to insulate that splice, it's going to be tough due to the oddball shape. That's why I'd start over and use shrink tubing. Truth be told, I'd probably use the crimp / solderless connectors with built-in shrink wrap that you already have in one of your pics. You'll just need a different size.