16 PIU Air horn install

Hey guys,
I'm trying to put a Whelen airhorn and PA in a 16 PIU. I've searched and found a thread from Jan 2017 about how to use a relay with the a horn ring curcuit but I'm still a bit confused.

The instructions say

If I want to keep stock horn while vehicle is Off, anyone want to help me wire this relay in? For some reason relays still confuse me.



Junior Member
I'm not familiar with the horn ring in the Ford PIU but when I would wire them into Tahoes the signal was as follows, 12V coming from the horn relay and then the steering wheel pad or button would supply the ground.

Looking at the diagram for your unit, the amp just needs a 12V aux signal to sound the horn, so without knowing how the Ford is set up I can't help you that great.

You would most likely need a master switch (or relay wired to ignition) of some type to operate a relay that would cut the horn and switch it to a horn ring circuit if you wanted to keep the regular vehicle horn while the airhorn is off.

If you can tell me how the factory horn is wired I may be able to draw up a diagram for you.

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