You need to check these details for the battery discharge, and even though you checked the relays, the engine control relay needs replacing, and then proceed as following:click here for details
And then you need to check the electrical harness getting to the tailgate, as this usually breaks, reconnect, at the tailgate hinge.
As for the horn, if the horn itself was checked, and the according fuse and relay were checked, you need to remove the steering wheel to check the horn's electrical actuation switch, and if that is good, then you need to replace the steering wheel control module.
As for the front wipers, if the fuse and relay are good, then you need to get to the wiper motor (in plenum chamber, under the windscreen in engine bay, covered in plastic trim), and supply the wiper motor with 12 v, if it does not work, it needs replacing, if it does work, then the wiper switch will require replacing.
Thank you for your trust! Get back to me if you need more info...Thank you in advance for the positive rating...