My Defender 90 (1999) when the engine is running and I put my foot on the brake pedal, the dashboard lights and front headlights and side lights come on dimly. And when I put my side lights on, my brake lights come on. I've cleaned the earths under the drivers seat and added some new ones, disconnected the battery and wire brushed the chassis terminal to get a good connection. Also disconnected and cleaned where it connects to the gearbox but this doesn't seem to have solved the problem. Are there any other earthing points that I could clean or any other ideas?