Brian,
You might be referring to the insulator-layer in the horn button retainer?There is an insulator layer in it.
truck horn contact parts and steering wheel assemblyThe way the horn works is a hot wire is always connected to the horn.
The horn mounting insulates/isolates the horn from ground (no honking).
The horn button creates the ground that causes the horn to honk.
The insulator in horn button might be bad/gone, and/or the horn button spring/return-mechanism is worn away and you have "continuity" (honking).
Maybe someone else will correct/clarify or debunk my suggestions?
