The relay that is clicking is normally a battery disconnect. It should not be clicking. You will hear a solid click when energizing, a lighter click when disengaging.
The brown wire will have a ground on through the door switch.
Step manualOP's imagesI am thinking that the system is not wired correctly. You should start by ensuring the battery disconnect is wired correctly. Check the wiring to the small posts. They should go to the battery disconnect switch.
Verify wiring to the step per the exact wiring for your step. Make sure the ground wire has a good solid ground. If it does not it can back feed power through the other wiring.