Re: 91 EGT horn
Where's the "click" coming from? If it's from the horn itself making a lame attempt to produce some noise, then the problem would be the horn, ie: it's getting power.
If it's a small faint click, this would be the relay engaging under the dash somewhere, which again is probably a good sign (its getting power)........they can still click on however and still not work.
Hold horn button on and check 12 volts at the horn with a multimeter. 12V = busted horn.
393 Tremec TKO 9"