Rear lights, instrument lights.

Are these connected in some way, as when i once did have them going intermitantly they both worked at the same time, now i have neither and they seem to depend on each other.

Anyone know the colour or the wires i should be looking for on the rear lights for the switched feed and ground on the lights and likewise on the instrument likes, as im getting to the point where im just going to wire the ignition switch light into my instrumentation.

got a new light switch and thats fine
checked the earth points at the fuse box and boot, fine.

I really will cry guys this has been going on for ages and nobody can help sniff sniff!