dt5 side lights and indicator problem

hi guy i hav a small problem with my works defender it a 53 plate ex souther elec and the rear side lights cum on when started and the indicator front and rear cum on to and when pressing the brake they get brighter thats side and indicators.I hav a going idear that is a earth problem tryed removing trailer plug socket still the same tryed putting on a new earth straght from light to body but this makes the intank fuel pump start priming eny idears where else to check or fixies would be much apperchiated