Basic electrical question, 08 Tundra

Hello. I’m in the final stage of adding a 12 volt usb adapter to my 08 Tundra SR5. The mount and usb adapter came with no instructions but sit where the center dash speaker would be. I have a red and black wire coming from the new usb plug but the cigarette lighter wires are different colors as you can see. Top right red and black are the new usb wires. I THINK the black wire goes to the black striped wire already in the vehicle and the red to the white. I have two splice connectors to accomplish this but I wanted to double check here first to avoid making a stupid mistake. I also think a shrink wrap barbell connector would be a better choice. Any assistance is appreciated.

 

Most likely, the red USB wire is for hot. Why not use a meter to check which existing wire is hot with the truck turned on to Accessory mode? I would think that the white with black stripe is hot, but checking it should be easy.

 

My experience with the OEM wiring is that the colors make no sense whatsoever. But you can probably just guess and if it works just let it be. You probably won't break anything if you get it backwards, but I don't know for sure.

Expanding on BakerShack's suggestion, a simple voltmeter/multimeter will show a positive value (not negative) when you have the red probe on the positive wire. Just set it to Voltage and DC. All hardware and automotive stores have meters but here's one on Amazon.

https://amzn.to/4aAqZK7

 

Its the J15 cigarette lighter connector you are looking at.
Grey is 12V power from the 15A CIG fuse
White/Black is ground.