1977 TA ,horn has never worked for me. I will chase this problem then I give up and move on. The horn works if you run a jumper off the battery and I have gone through the steering column with new parts such as neutral switch, horn contact parts and turn signal switch and bearings. The horn never worked before and it still doesn't. I have battery power at the relay plug by the fuse box. When the relay is unplugged the wire to the horn is grounded, when the relay is plugged in, there is no power at the horn, nor is it grounded either, no matter if you push the button inside or not. I think I have wires touching somewhere, but where? I have tried new relays to no avail. Thanks for looking at this.