Reverse camera LEDs turn on but camera won't come onto the screen

[the evil twin]

Different manufacturers don't follow a common wire colour code. So you really need to find a diagram as @Fireblade posted.

Yep... agree with you and Fireblade

I have found orange, purple and blue/grey at various times but no doubt there are Manuf using others as well... and if it is orange there are usually more than 1 as they use that colour for any combo of memory 12, ACC 12 and Rev Cam Auto On...