Another bee sting - cant get horn to work in GQ Patrol

[PeeBee]

Have you measured the voltage when the horn is pressed?

Mark, good question as I see the power comes off a constant power source, so should be 12V, however its dead, perhaps indicating there is an issue back in the loom. If I jumper the power directly off the battery into this power wire, I get a pissweak response at the horn, and if I leave the jumper on with constant power, the response is zero pushing the steering wheel pad. The fuses are all fine.. Almost looks like another cable connection may be missing or a plug not connected, however the wires all disappear into a taped up loom, so unsure thats a line of enquiry.

I will see if I can measure the transmitted volts when doing the battery jumper next time I am at the shed. Frustrating.