Any tips on where I might find the horn relay and what it might look like, on my 78 Itasca Sunscruiser?
Well, I don't have a suncruiser so can't help you with a direct answer.
However I've found things by just tracing the wires. if you can't because they're packed I get my trusty multimeter out, put it in search mode ( ->+) look at the colors of the wires at the horn and start measuring the same wires at the other side. However if your previous owner was a wiring magician like mine the possibility is there that the wiring colors on the other side are completely different, so don't pin me on this one, please ;)
Also looking at rock auto for the part helps a lot. I have a Dodge and not a Chevy but if your RV is based on the P30 chassis you'll get this.
I've got the chevy chassis and yeah, I've had the multimeter out for some time ... the ring to ground gets no voltage.
Looking for continuity - I haven't found anything from the ring to anything. The wiring diagram says that the lead should be dark green though. I'm going to go back in there tonight with an alligator clip on the ring lead (rather than doing contortions trying to hold both).
So I took things apart and there was a layer of sticky rust under the ring - preventing proper contact (seems like a soft drink was spilt there once upon a time)... cleaned that up and it's working now... so, gross, but yay?
Yes, this is exactly the reason why I'm not a fan of chassis ground. It all seems ways more sensitive for faillure.
But isn't it wonderfull when it works again and you fixed it yourself :D
Yep, really flexing that computer electronics diploma. ;)
That said, I never did find the horn relay. :)rotflmao
It is so strange how you so mentimes miss posts.
Can't you trace your wiring from the horn or the horn button. If this means removing insulation, I've done this and with success.
It can very well be that the PO removed the Relay and didn't put another back. A lot of people just don't seem to care much about safety anymore.