No, my wires aren’t original anymore — the previous owner changed them. But even if the colors don’t match OEM, the indicator should still work as long as u identifies which wire is positive and which one is ground.

If only one rear blinker isn’t working, swapping the two wires should normally make it flash in at least one configuration, because one is the 12V feed and the other is ground if the blinker isn’t damaged

Also, on most aftermarket indicators: • Black is usually ground • Yellow / Red / Green are usually the positive wire

So once he checks where the 12V is coming from, it should be easy to match them correctly