freelander 2005 td4 possible earth problem

Good day to all members,recently converted to a 13 pin towing socket using existing 7n wiring and heavy duty grey 7 core for extra charging /fridge etc coupled with necessary voltage sensing relay and fused live 32 amp feed.connected to caravan and everything worked fine,even without replacing existing 3 pin flasher unit,being aware of the law however i sensibly decide to fit the recommended lucas 4 pin to enable dash towing light to work,have not tested on caravan yet,but when indicating tow light flashes once brightly then flashes faintly in unison with standard indicator warning light,also when using wipers on any speed the flasher relay ticks and the towing light glows faintly in unison with wiper strokes,having had this sort of problem in the past with ford wipers working washers and similar washers working indicators etc i found it to be a bad or lose multiple earth connection point ie,stud and nut with loads of earths to it,cleaned and tightened all faults remedied,does anyone know where i might find such earth points on my freelander or any other advice appreciated,thanks in anticipation of any advice