Horn wiring question

[CPNE]

How is the horn wired? Specifically, are the dk red and dk green wires coming off the fuse block, that plug into the relay bolted to inner firewall the key? How can I test where my horn is failing? Do I test at the firewall relay, and if so, how should I test it? From there where does the voltage travel? I assume to the heavy dk green wire that attaches to horn near voltage regulator.

Can I test if the horn works by running a hot wire from battery to it?

Basically, my question boils down to:

Where are the points of failure starting with the wiring from the column and ending with the spade connection on the horn on the rad support? ...and how do I test each point?

[dubie]

hmmm not sure on that one Jeff. My molested truck has a button on the dash where one wire goes to the horn and the other to constant power . I don't have the horn wired to the steering wheel anymore.

[CPNE]

Originally posted by dubie
hmmm not sure on that one Jeff. My molested truck has a button on the dash where one wire goes to the horn and the other to constant power . I don't have the horn wired to the steering wheel anymore.

I can do that for inspection purposes, but you know how I hate "backyard" engineering. I want the horn to work as engineered by the good folks at GM

I just went thru this thing and replaced all the chopped wiring with unmolested originals, as I can't stand non-stock wires and wire nuts. Makes trouble shooting much easier when 30 years of hacks are removed from the equation.

As you can see from my questions, I still have a brake light and horn issue.

[cdowns]

yes you can run a hot 12 to the horn to see if it works, i like to take the horn out of the truck and cleanin the mount area to make sure of good ground then clean the contacts in the connector (heavy green) that go to horn if the horns good take multi meter or testlight to the drk green wire and see if you have volts there whgen hittin the button

[CPNE]

Originally posted by cdowns
yes you can run a hot 12 to the horn to see if it works, i like to take the horn out of the truck and cleanin the mount area to make sure of good ground then clean the contacts in the connector (heavy green) that go to horn if the horns good take multi meter or testlight to the drk green wire and see if you have volts there whgen hittin the button

Thanks, that's what I thought. Now if horn works using the hot wire test, but no volts at green wire, working back, what is the next point of failure?

[JimKshortstep4x4]

Jeff,

My experience has been that the contact in the horn button is the major problem area. The shaft/column has to be grounded so problems with the rag joint ground are common.

I would start with the horns first. Run 12 volts to each horn. If they work, run 12 volts to the green wire at relay. Relays very seldom fail, but you might ground the wire from the horn button at the relay. I don't remember the color but it is not red or green and it is smaller than the power and horn lead wires.

If everything is working at this point only the wire, column ground, horn brush and horn button contact is left to check. Pull the horn button and run a ground wire from the retainer to a known ground. If the horn blows than the horn wire/horn brush are good. Ground the retainer to the steering column. If the horn blows, the column/shaft ground is good and there is a problem with the contact.

If the horn does not blow there is aground problem with the column/shaft.

Good luck!

Jim

[CPNE]

Spoken like a man with experience. Thanks again Jim!

[jorgensensc]

Just to give you an idea, My horn works great, the problem is that when I turn the steering wheel it will intermittantly go off, giving a little beep. When you push the horn button, it completes the circuit by grounding. When I turn my wheel, the horn button inside grazes the metal,thus creating a complete circuit, hence my random 'beep'.
That's why I unplug mine until inspection time. I wish I could leave it plugged in, but the crazy beep is enough to freak out other drivers all the time.
Shawn

[JIMs70GMC]

Fixed mine today. Started at the relay and verified 12 V on the red wire. 2nd put a ohm meter between the black wire and ground and pushed button should get a short-did not so I moved up to the steering wheel and removed the steering wheel, but first the button sticking up I shorted to the center and looked for sparks(relay was hooked back up) no sparks then took steering wheel off and shorted the next button to the center of the column threads and got sparks so I figured the problem was the cancelling cam which has the first spring loaded button. But had anothe problem had the relay click but no horn so I cleaned up the horn mounting and now I have my horn. Here's some pics:

[JIMs70GMC]

I replaced the dirty cancelling cam with the clean one that came with an auto column I had.

In this pic at about 1 o'clock you can see the horn contact that allows the 360 degree motion. I shorted it to the center there.

[JIMs70GMC]

Conected a test light between ground and the green wire at the horn to verify 12 V was making it. Then I cleaned the mounting of the horn for a better ground.