Okay boys, what did he do wrong?

Those wire taps tend to break about half the stranding on the wire into which they tap. I spent a while removing all the one the previous owner of my vehicle used. The wire stranding on every wire near a tap was broken and severely corroded. I had not had issues at that time, but it was just a matter of time.

This eTrailer Link
shows the center pin as Backup while the diagram above calls it AUX.

On the linked diagram, Yellow looks like what should have been connected (Called "reverse lights) to the Hot side of the LED, and its Ground wire should go to White/Ground. If it's LED, polarity matters. The light's ground should be on White.

If the LED is connected to the 7-way, make sure the wiring isn't damaged or loose.

Like RoyB said, most likely whatever color is to the Center Pin for the Hot, and Ground to White, Terminal #1, or any other good Ground.

Those pinch things are called Scotch-Locks.

Thanks, just seemed odd to see the light go out, so figured he used the wrong wires, but maybe the ground will be the issue.
Thanks

This is a typical wiring pictorial for the 7-way trailer connector.

Most of the time the center pin is use for BACKUP lights.

Confirm this with a MULTIMETER to be sure...


Photo from GOOGLE IMAGES

also note in my case my FORD truck ignition key must be turned ON before I get any DC readings going back to the trailer connector.

Roy Ken

Correct. YELLOW is the back Up light wire color. The Green(if standard tow wire colors are followed is the tailight signal wire). So, you are getting a feed back. The Ground on the Tow plug is the large white wire. Doug

I believe if you disconnect what's been done & determine which wire is hot & which ground for the light itself then connect the hot directly to the back-up light circuit you'll have better luck. Should be pretty easy.

Usually when symptoms like that arise, it's because of a missing ground.

Ha! I know the answer but I'm not a boy, so, oh well.

Bad ground connection.