Horn on GQ

[Yendor]

I wonder if anyone has any more advice? Problem is certainly between the steering wheel and the the relay (under the metal plate near the battery) as if I bypass that with test lead the whole circuit works.

The steering wheel switch receives a single wire to its centre. This wire disappears into the steering shaft, but where it goes from there i can not tell. Also the wheel itself appears to provide the earth, so maybe its not brushing correctly to the chassis? I'm really not sure.

Anyway, managed to pass the roadworthy check so its not too drastic

This should be a Light Green wire with a Black trace.......if you touch this wire to earth does the horn work?

Yes the horn switch provides an earth to complete the horn circuit (it gives an earth to the Light Green wire with a Black trace).

There is a little pin that runs on a metal plate on the back of the steering wheel, this pin can wear out. Have a look and make sure the pin is still making contact with the back of the steering wheel.

Do you still have the genuine Nissan steering wheel fitted?