Assuming that the trailer has not previously rewired. The Scamp wiring diagram in the Doc Center lists the following.
Right Side:
White - Ground
Green - Running
Lights
Brown - Turn/Brake
Light
Yellow - ? (Maybe Backup)
Left Side:
White - Ground
Green - Running
Lights
Brown - Turn/Brake
Light
Yellow - ? (Maybe Backup)
From what you said, it doesn't appear that you have all the same colors.
As for as the new tail light:
White is probably ground since it has the round lug on it.
Red may be the Turn/Brake light since it is the larger size.
Black may be the running lights.
You could hook it up and see how it pans out, may have to switch the red and black on the new Tail light to get the proper function. Hitting the
brakes should make the brightest lightwise from the new Tail light.
Hope this helps!
Spanke