I’ve taken the advice here and cleaned/greased the contacts at the switch, and I had already disassembled and cleaned the spade connectors at the horns. I found a great YouTube video by the NPD guys that takes you step by step through the trouble shooting procedure. It was on a '65 Mustang, but very similar to the Cougars. Here’s what I did/found:
- Checked battery voltage and verified 12.7V.
- Connected each horn directly to the battery with jumper wires to confirm that they both work. They do.
- Removed the horn ring and checked voltage at the switch contacts. Found 12.6V there.
- Jumpered the switch contacts and checked voltage at the horn spade connectors. Found 12.6V there as well.
- Plugged the spade connectors to the horn and checked voltage (switch still jumpered). Found ~7.5V and no honk. Just the click/buzz I’d mentioned before.
- Suspected bad grounds at the horns so I jumpered the ground connections directly to the batter negative post. Still ~7.5V and no honk.
So, I’m stumped. The horns work fine pulling 12.7V directly from the battery, but only click/buzz with 12.6V from the wiring harness. And they appear to be drawing about 5V in the process. Thoughts, ideas, suggestions? I’m at a loss. I’d really love to get this thing tagged and on the road with some nice weather left.
Thanks