I have a 1990 Defender 90. My tail lights work but no brake lights. I crossed the wires from the switch and nothing. I checked the fuse and its fine. I don't know how to use a meter so any help would be greatly appreciated. Haven't checked the grounds yet.

Also check the continuity of the bulb holders, as they can cause problems ...

So I want to just re wire the 1990 defender 90 200tdi rhd. Any suggestions how and I'm not to savvy with electrical. Is this something I can manage on my own. Basically I want to untangle the original mess that's in the back where all the lights meet and the trailer connector. Any and all suggestions are welcomed please.

If you are talking about the area by the rear door lower hinge behind the triangular panel that is always a bit of a mess. its the nature of the beast, the main loom, trailer loom and all rear lights connect there so it will always be messy as they used bullet connectors rather than multipin ones. Worth getting yourself a meter and learning, basic electrics like lights are generally fairly simple to understand. If the thought of electrics scares you just think of it as a garden hose sort of system, if the hose is your wire then the water is the electricity. Voltage is equivalent to your water pressure and current (Amps) is your water flow rate when you open the nozzle (which would be your bulb). Your tap is the equivalent of the brake switch as it controls the water (current flow) through the hose. Well worth learning the basics as it will save you time / effort / money in the future.