The first and easiest thing I would do is have someone press the horn button while you listen for the faint click of the horn relay inside the TIPM.
If you hear it click, the problem is in the TIPM, or after it; fuse, bad connector, bad wire, bad horn.
If you don't hear it click, the problem is in the TIPM, or ahead of it; most likely a bad horn button, or a bad clock spring in the steering column.
2008 Unlimited Rubicon Automatic
Last edited by ronjenx; 07-02-2012 at 10:15 PM.