Need Help with 72 Horn

orange911 · 07:24 PM

I am trying to get the horn working on my car and I have discovered that the brown w/ white wire from the horn button is not plugged into anything. The plug that connects to the horn under the fender has a black w/green wire for the + lead, solid brown for the ground.

Upon futher investigation, I noticed under the dash that there was a black w/ green w/ white stripe wire (male end) and it is plugged into a black wire on the same harness (see picture), not to the brown wire from the column. Is it suppose to? I tried it, but it still did not work.

Where does this brown wire go? Does the brown wire from the column connect to a + or - lead? and can someone tell me where the female end black wire goes (in the picture next to the black w/green and white wire) ? It has a solid black sheathing on it and I cannot tell what wiring color is underneath - may be black with white dots??.

Thanks in advance. I really want to avoid purchasing a wiring diagram and futher debilitating my eyes.

jstobo · 05-02-2005, 08:36 PM

So you want the rest of us to strain our eyes to save you a few bucks. Actually , if you go the Pelican Parts Home they have several electrical drawings available for free and in color to reduce eye strain. But to answer your question. The horns get their power from the horn relay. The horn relay has power to it all the time(from the fuse box). When you ground the brown/white wire at the steering wheel(pushing th horn button) it completes the circuit to the relay(by providing ground) and the relay switches the power lead to the black/yellow going to the horns. Check your relay, they go bad. Also you can put 12 volys directly to the horns to make sure they work. In a 911 brown wires are ground and brown/white is switched ground. Good Luck.

orange911 · 05-03-2005, 03:45 AM

Thanks for the info. Where is the horn relay? Can you please provide the link for the wiring diagrams?

ART C. · ART C.'s Garage

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304065 · 05-03-2005, 04:44 AM

http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_1971_Part-2.jpg

304065 · 05-03-2005, 04:54 AM

Olin,

I know a fair amount about the function and repair of the early 911 electrical system.

The reason I know anything at all is because I spent the first couple months of my 911 ownership fixing the wires after I caused an electrical fire behind the dash.

With that admonition out of the way, please unplug whatever you plugged. There is only one important wire for the horn, and that's the brown wire with white stripe. Mr. Stobo has explained it exactly.

The wire colors aren't random, they conform to the Deutsche Industrie Normen (DIN) standard, even back in 1972. As such, if you see a brown wire, chances are very high that it's a ground wire. Don't go plugging a ground wire into a positive lead anywhere unless you have a fire extinguisher handy.

Good luck! Check out the diagram and then check back here.

orange911 · 05-03-2005, 02:09 PM

Hey folks, give me some advise about where to locate the relay. Is there suppose to be one directly under the dash - cause I don't see one. That brown/white wire barely extends into the dash, so is there a leader that goes to the relay from there or is there suppose to be a relay right there.

I understand the concern about the safety of electrical fires, so I did unplug it immediately after realizing it was not correct. Thanks for ensuring I did. I will review the wiring diagram tonight.

orange911 · 05-03-2005, 02:36 PM

Never mind, I found it behind the oil pressure gauge.

wallstreet · 05-03-2005, 03:14 PM

Quote:

Originally posted by orange911
I am trying to get the horn working on my car and I have discovered that the brown w/ white wire from the horn button is not plugged into anything. The plug that connects to the horn under the fender has a black w/green wire for the + lead, solid brown for the ground.

Upon futher investigation, I noticed under the dash that there was a black w/ green w/ white stripe wire (male end) and it is plugged into a black wire on the same harness (see picture), not to the brown wire from the column. Is it suppose to? I tried it, but it still did not work.

Where does this brown wire go? Does the brown wire from the column connect to a + or - lead? and can someone tell me where the female end black wire goes (in the picture next to the black w/green and white wire) ? It has a solid black sheathing on it and I cannot tell what wiring color is underneath - may be black with white dots??.

Interesting. I am working under both front fenders and I see loose wires - taped-up. On the passenger side, is the black w/grn & I believe a white wire set. These wires have a connector which appear to be the horn wires. There is a horn but not connected. I connected to the horn and horn does not work; might be bad horn. Then there is a similar set of wires with no connects: maybe fog lamp wires?? On the driver side, there is the same sets , one horn that is connected and works with the horn button. Wires come from wire harness on left front under hood near fuse block; they pass thru inner fender. Also, appear to be second set of horn wires on driver side "pigtailed" from the wire to horn. Should 1970T have horns on both sides? Why two sets of horn wires? I have not looked under dash inside car.

jhallen · 05-03-2005, 03:55 PM

My 1969T has horns on both sides. Now my question. My horns will sound at random, but usually when making a left hand turn. Any remedies? Ironically, while you are attempting to make yours work, I've disconected mine, as driving along with the horn going off at randem has proved somewhat distracting for myself and other motorists.

wallstreet · 05-03-2005, 04:41 PM

Quote:

Originally posted by jhallen
My 1969T has horns on both sides. Now my question. My horns will sound at random, but usually when making a left hand turn. Any remedies? Ironically, while you are attempting to make yours work, I've disconected mine, as driving along with the horn going off at randem has proved somewhat distracting for myself and other motorists.

Suppose there might a grounding problem with the horns or the turn indicators. I believe mine has had a "yellow solderless connector" attached to the brown ground at a marker lamp. Maybe a previous problem occurred with the ground on my car. Possibly your grounds are corroded somewhere in the turn lamps or the horn or at a common ground??? The fact that the horn honks on turns leads me to the turn circuit. Check the horn pick-up at steer wheel.

orange911 · 05-04-2005, 08:03 PM

Found the problem with my horn. PO disconnected the relay (by the fuse block) because horn circuit was continuosly closed. I presume there is an easy repair here since the button housing is cracked badly and may be pinching the contacts together.

BTW I posted earlier that the horn relay was behind the oil pressure gauge - that one is actually the hi-beam rely. They are both the same type and make.

Look at the wiring diagrams and you will see that horns on both sides is an option.