As an EE, I totally agree it would be easy. I never bothered to take the string wrap off to see that they used. But, my guess is that it's a diode.Their website shows products for those options and they have videos for install in the refreshed trucks. Not sure I'm interested in all that, just seen it browsing.
What's spliced in line in that jumper wire? A diode? I could make one of those jumpers in about 2 minutes. I've got all the wires and connectors.