Trailer hitch wiring diagram. Need help

It depends on your country laws and the trailer setups. There are basically THREE separate types of trailer (and vehicle) systems

1 Is the type on your mopar. You have the stop and signal with one filament, in which the signal switch disconnects the brake light power from the bulb that is acting as signal

2 you have SEPARATE brake lights and signal lights in which the signal lamp lenses are AMBER

3 You have SEPARATE brake and signal lights in which the lenses are RED

If common trailers "over there" have signal lamps with red lenses, you are all set.

Just hook your tail lamp line from your car to the tail lamps on the trailer

Hook up a ground

Hook up the left and right signal wires from your car to the trailer.

In this case, it won't matter if the trailer has separate brake and signal lamps IF THE LAMPS are all red

The last possibility is that your country REQUIRES stop lamps to be red instead of amber. If the trailer has separate brake and signal lamps but the signal lamps have amber lenses, then you can NOT use them for stop lights if that is the law there.

In this case, here in the states, manufacturers such as Valley make "converter boxes" which have solid state circuits in them, and which allow the intermix of these two types of systems. Their most common use (over here) is to take a car with separate brake and signal lamps and convert to "integrated" stop/ turn lamps such as your car has now.

It appears that Valley converters are only for what they are calling 3 way to 2 way, the last I described:

http://www.vtowing.com/TaillightConverters.aspx

Another thing you might consider is rigging up a set of temporary either magnetic lamps, or lamps which you can easily screw to the trailer, IE mounted on a strip of lumber, etc.