Horn does sometimes works, sometimes not

[fixkick]

(button pushed) !!
if relay pins measure. and  12v,12v,0v and 0v on pin 4 the relay bad! (pins 1,2,3,4)
easy to prove. (using any voltmeter) (2 persons)
the whole purpose here is 12vdc,  to pin e17/18 of horns but...
and never 12vdc at e160/e161, if yes, the grounds at horn base are bad. for sure.

if the horn only fails with steering pointed in just one directly, only, the  clock spring is bad, , expense part and hard to replace, steering wheel pulled. (I have a puller so is easy for me)

your relay clicks;  this implies clock spring is ok,  and never assume it is bad first. only last, as IT  is the hard job here, all others are easy fixes HORN but , for sure a new relay.
this video shows how it works be happy you do not have car with radio knobs and other features+ NAV in the steering wheel all wanting to fail and air bags, this car is just 1 wire horn in the clock spring
this even shows the spiral spring wire, wound up inside.  (my jeep just failed this, after the dealer did the recall to it , he broke it 2 times in a row, so I fixed it my self) 

https://youtu.be/862izi6XChI

now you  know not to guess clock spring, see?  (very costly fix) , fuse 12 is here.  if stop lights work the horn power is good. USA SV418