I would be happy to help. However, without a scan tool, what can be done is limited. First, we can check for power at the horns. I attached a wiring schematic below showing the horns' power supply and ground.
Using a test light or multimeter simply check the gray wire with a yellow tracer for power and the same on the other horn, but the gray wire with the light blue tracer. Simply have someone press the horn button to see if power is present. If there is power, check the black wires for continuity to ground.
If you look at pic 3, it shows the possible causes for the issue. Notice that the tests are done using a scan tool. Is that something you have access to?
Here is a link you may find helpful when testing:
The idea that you don't hear it when setting the security is leading me to think it could be the circuit board in the integrated power module. If that is a possibility, then you should have the CAN-bus system scanned. CAN stands for controller area network. Basically, all computers/modules are tied together via a few wires. This type of scan will retrieve codes regardless of the module storing them. Here is a link showing how it is done.
I wish I had a very simple answer, but today's cars are so much different than in years past. If you noticed in pic 3, a lot of the testing does require a scanner as I mentioned above. The scanner can at least tell you where to check.
I hope this helps. Please let me know if I can help in any way. Also, let me know what is found.
See pics below.
Images (Click to enlarge)
Monday, December 13th, 2021 AT 4:41 PM