Horn problem with CVPI 02

I have an ex CVPI 02 police car but with police package removed. So now it's a normal CVPI. The problem is that the horn is not working.

I already checked the fuse n°5 (15 amps) and relay n°2 and they're good.

The guy who sold me the car told me that 2 wires under the steering column that goes from the wheel switches have been disconnected because before there was an air-horn who has been removed.
So I want to know which color are these wires that connect the steering wheel switches?
I'm also interested to have a schematic of the horn. ARRC at EBSCO doesn't work anymore.

When I press on the switches buttons, I don't have 12V on the relay n°2 coil. Power only at one side of the coil, no return.
So it's really a problem with the 2 wires.

Here is the short and sweet wiring. You might want to enlarge it a little. :)

Thanks for your schematic.
I'll check the 20 D6 connector.

Ok I just fix the problem. The blue wire from the 2x2 connector was cut. Actually there was 2 cutted blue wires. The both from the steering wheel were giving same GND signal when I press the horn buttons. So only one of them is enough. From the relay input section, only one of them were connected to the relay. It gaves 12V (through the relay coil). So I just connect one wire from any of the two wires from the wheel to the right one at the other end side.

I'm sure they're cut to plug an siren/air-horn module between the two wires extremity.

Also the horn connector at front bottom center of the radiator was not fully inserted. Now it works.

The second blue wire is connected to the BCM so when I press on the panic button of the keyless entry remote, the car make multiple horns.

So the 2 blues wires from wheel should be connected to the 2 blue wires that go in direction of under hood. The 2 wires from the wheel are already tied together. So all 4 wires are indirectly connected together.