Looking at a used truck tonight

[Jay2TheRescue]

I don't think the problem is in the column anyway. Unplug the horn relay and check the voltages at the terminals. That's where your problem lies I bet.

[IndyFetch]

I don't have a meter. I'm thinking about just wiring in a separate horn button on the dash through the fuse box (lots of spare slots since I just have a work truck) and connecting it to a new horn.

[Jay2TheRescue]

I would not do that. I wonder if you could simply put a jumper on the fuse block to supply continuous power to the horn circuit. (make sure you're not bypassing the fuse)

[theholycow]

You should invest in a meter. Harbor Freight often has a decent one for $4 or less, although they're currently $5. I have a few of the cheap HF meters, they work great.

[Jay2TheRescue]

I concur. Buy a cheap meter. Once you have a meter, it will be one of the first tools you grab in cases such as this.