Hello I have a 2016 f-150 and my horn sounds weak like one of the horns went out? I’m not sure if it’s the wiring harness or the horn itself? How do you test to see what the problem is?

 

First you have to find the horns. Sometimes they can be difficult to get to.
If you manage to tap the horn(s) sometimes they will respond and work normally ,especially if not used that much.
Some vehicles require a horn relay due to the load of the horns. The relay is working otherwise you wouldn't hear anything .
Let's see if the tapping corrects the condition.

A little tip, stuff a rag into the horn(s) and that way you won't annoy anyone and if they work correctly , you will be able to know even if there is a rag in there temporarily.

 

so you mean actually tap the horns themself? What do I tap them with? How do I make it sound while tapping on it?

 

The horn contains a vibrating plate. Sometimes it gets corroded from moisture getting into the assy and sounds sick. I have never broken one and they are pretty durable.
Start with the handle of an average size screwdriver. A couple of raps might loosen things up. Better if you can do the banging while someone is holding the horn button , down and that's another reason why we use the rag , You're right next to the horn..


If you can't get anyone to hold down the horn pad, remove the wire from the horn and run a jumper wire direct from the battery positive terminal to the terminal on the horn. It should blow.. Just connect the jumper to the horn first , then momentarily touch the other end to the positive terminal of the battery FAST !

 

The horn is behind the grill. They are wired together, if one works then its not a vehicle harness issue.
If you have a keyfob with a panic button that will set off the horn, its how I check for voltage at the horn connector.