Hello, when you say "reset the display", did you disconnect the battery or unplug the display? The Body Control Module (BCM) controls the Horn in these trucks, the switch in the steering wheel is grounded when pressed, this signals the BCM to ground the Horn relay. I think what might be happening is a diagnostic trouble code might be setting in the BCM, (which wont trigger the check engine light) and the BCM is shutting down that circuit due to a fault somewhere. I have repaired these exact issues in Ford trucks, most of the time its a wiring issue, but you will need a capable scan tool and the first thing I would do, is when the horn stops working, I would check the BCM for any stored trouble codes, and you can also look at live data from the BCM, so for example there will be a data PID (an ID) for the Horn switch. It will read On or Off depending if the horn is pressed or not. This is where if the the BCM is detecting a fault somewhere in the circuit it can most likely turn that circuit off to protect the BCM or other modules from damage.
I would also recommend to do as much with a scan tool as you can to begin with, because once the BCM connectors are unplugged, if this issue is within the wiring harness or connectors, the problem could mask itself and be very difficult to find in the future.
Ill post the wiring diagrams for the Horn circuit though, so you have them.
You'll be able to see how the circuit actually works.
Wednesday, January 7th, 2026 AT 12:25 PM