wiring is fine, as it is all new, i replaced the switch gear at the same time as the lights.

Hi, im trying to get an MOT for my MK-3, The tester has failed it on the fact that when the indicator is flashing, it causes the head light to dim ever so slightly, i have tried re earthing all lights seperatly, and even turning the idle speed right up just for the MOT, but it has had no effect. Can...