electical gurus: I need your horn wiring help

[sandwood]

This is for a 1988 951, and I believe it originally had airbags. I bought the car with a momo competition wheel with a non-functioning horn.

In the steering wheel hub there is a black wire that appears to be soldered to the hub with a spade terminal that was connected to the metal ring that goes between the hub and the wheel - no volts. Also in the hub is a single brown/white or brown/blue wire with a yellow plastic terminal (12 volts), and two wires that end in an orange terminal (I suspect for the airbag).

the back of the momo horn button has 2 spade terminals, one with a ground symbol.

my understanding is I shd connect the ground from the horn button to the hub or to the ring between the hub and the wheel. when you push the horn you close the circuit and the horns beep. But can anyone confirm which wire to connect for power?

I've tried the brown wire and nothing happens. Does the car need to be running? or is accessory power ok. I checked the connections to the horns themselves and they seem fine - a black/yellow wire and a brown wire run off them into the wiring loom. the fuse is fine and I tried swapping relays, all to no effect.

HELP! I need to fix this before taking the car to pass inspection. Thanks, Alex

[Wipeout]

I've found that the car has to be running for the horn to work.

[sandwood]

I guess there's no difference between 2 click in the ignition and actually running?

[Wipeout]

My horn I don't think works unless the engine is running.

[sandwood]

ok, so that's something to start with. but does anyone know the color of the actual hot wire for the horn button on a 1988 951? thanks.