Disc "seems" OK. It remains a suspect. We are in the process of eliminating suspects to expose the culprit. Could be a conspiracy of several parts. This is the art of troubleshooting. Understanding the problem, logic, testing and sometimes shooting from the hip (guessing) and replace parts just to get any reaction and try to get lucky. We don't all have the equipment, know how or ability to analyze results of some tests. Any way you can figure it out is a good way.
Provided the plunger is inserted correctly and is still spring loaded; Here is the next test.
Examine the plunger and it's operation.
Take off all horn components except install the plunger. Use a jumper wire or any conductive tool to touch (push down) plunger button and touch steering wheel metal (or the nut) at the same time. I hope the battery is connected during all these tests. If the plunger test honks, you are happily 95% there.
After you get a honk from the plunger test, you will know for sure it is the upper bits. That is what that test is for, so you know where to zoom in.
Your story about it honking when reassembly, indicates something wrong with the little bits or method of assembly. Keep playing with the parts up there now that you know how it all works, you can move them, push them, find a honk. Then you will realize what is wrong. It could be disc for sure. It may not be contacting around the nut area. Use a screw driver to make it contact. By manipulating things you will get a honk.
If this does not produce a honk, here are the options:
One at a time in order.
1. The slip ring could be oxidized but should honk somewhere from wheel lock to wheel lock. So try honking while rotating steering wheel in all positions. If you get a honk, remove wheel and LIGHTLY clean the copper slip ring.
2. Be sure to do your best to inspect the horn wire going down column. Inspect ALL THE WAY to the relay. Not much can be wrong. If it is shorted, it honks. It would have to be broken.
3. Post pics of your parts individually and assembled. Pic of relay. Pic of horn trumpet. The trumpet MUST have a good ground to it's bracket/case/housing thru the way it is bolted to truck. But the relay test showed it does. However your story could possibly indicate the dreaded intermittent electrical issue
.
If no results, Do a continuity test on the slip ring. This would be done with wheel removed. One probe on the slip ring, one probe touching the removed green wire at the relay. Removing that bearing/slip ring is a last resort. Not until positive that it is bad, which is unlikely. Unless someone has pulled the wire and broken it off.
