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  #1  
Old 02-14-2011, 12:57 PM
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rreed rreed is offline
350 Buick
 
Join Date: Aug 21, 2006
Location: Texas
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Another Horn Relay Question...

Searched but can't find it now, need to get my horn working. Some years ago my horn did the dreaded constant blow w/o shutting off in the middle of the night when temps dropped below freezing. Would also randomly blow when you move the tilt column. Anyways, removed a small white three prong relay from some harness under the dash to shut it up.

Fast forward years to now I need my horn working for stupid TX inspection. I think/thought it was a brown relay harness under the dash near the parking brake? It fits in there but when I plug it in, my aftermarket radio comes on and the horn still does not work (stop laughing).

We'll say the cab/wiring is approx. 1985 J10. Any ideas please?
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75 CJ-5
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  #2  
Old 02-15-2011, 11:24 AM
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Reed,

I recently had issues with my horn not working. I discovered the plastic cap that surrounds the horn relay was missing, leaving all of the internal wires exposed. So I bought a relay from AutoZone, and the horn still would not work. I then broke out a multi-tester and began testing all of the wiring, as I assumed the relay was no longer the problem. Turns out my new relay was junk and did not work. Bought one from NAPA. Now my horn works. A TSM is invaluable in this situation. My TSM walked me through the testing procedures for the horn and horn relay system. Go to http://www.oljeep.com/ and see if they have one for you vehicle. You said the wiring is "approx. 1985 J10". I take it this means it has been pieced together from several vehicles. My Jeep is a 1977 Cherokee and I can take a photo of the horn relay location if you like. Like you, I had to have my horn working in order to pass a Texas inspection. Working on making mine a daily driver someday.
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  #3  
Old 02-15-2011, 12:04 PM
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five16 five16 is offline
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What station does the radio play? I don't know that it would help with the diagnostics but it would seal the joke
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Old 02-15-2011, 01:31 PM
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350 Buick
 
Join Date: Aug 21, 2006
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Quote:
Originally Posted by five16
What station does the radio play? I don't know that it would help with the diagnostics but it would seal the joke

Okay that was funny. Haha, anyways it's just weird the radio came on (switched power to it). My relay should be good, it was removed working.

While the truck is a mutt I'm reasonably certain my cab/wiring is '85. It VINs as an '85 and wiring/dash/etc. appear to be period correct.

Before I removed the relay the button worked fine. For starters I suppose I need to know which harness is it supposed to be? The brown, three-prong one?

Is there a single wire that comes out of the column for the horn or is it part of the turn signal "ribbon" harness thing?
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47 Willys
75 CJ-5
81 Scrambler
76/79/80/81/85 J20 (all the same truck)
86 Grand Wagoneer - FOR SALE!!!
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  #5  
Old 02-15-2011, 04:18 PM
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Horn relay wiring. Looking at the diagrams on Oljeep, http://oljeep.com/gw/elec/84_85/84_8...gramPage17.jpg

The red wire with tracer travels from the horns themselves to the horn relay (through the firewall and fuse box). The larger solid red wire at the relay connection is the power source. The black wire with the tracer is the wire that travels up into your steering column. I am not familiar with a 85 J10 wiring, so I do not know if you have more than one three prong plug in under your dash for relay switches. Look at the one you think is the horn relay and trace the wires to see if they match the wiring diagram. If they do, you know you have the correct location for the horn relay. If your horn still does not work after you plug it in, you will need to diagnose the issue to see why the horn will not work.
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  #6  
Old 02-15-2011, 05:31 PM
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Aha... Hmm.. I do seem to recall swiping the digital clock yellow wire for my switched source for the stereo. haha I'm not sure the details but this diagram (thank you!!!) appears to have some sort of connection (ground?) to the horn relay? Will have a closer look when I get home but at the very least it will help tremendously in ferreting out the wiring.
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47 Willys
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81 Scrambler
76/79/80/81/85 J20 (all the same truck)
86 Grand Wagoneer - FOR SALE!!!
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  #7  
Old 02-16-2011, 09:22 AM
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Seriously, I would think you have a ground problem. Your relay is probably fine.
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  #8  
Old 02-18-2011, 12:03 PM
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Does anyone know if the horn wire is its own single wire out of the coulumn, if it's part of the turn signal ribbon, etc.? Where does the horn wire come out of the column please?
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47 Willys
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81 Scrambler
76/79/80/81/85 J20 (all the same truck)
86 Grand Wagoneer - FOR SALE!!!
96 ZJ

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  #9  
Old 02-18-2011, 01:02 PM
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On my 77 Cherokee it is part of the turn signal ribbon, and is the solid black wire coming out of the steering column.
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  #10  
Old 02-18-2011, 01:33 PM
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Where the heck is my horn relay on my '82 J20? I looked in the manual, and there's a relay under the dash that could be it. I think my PO had air horns, and stripped that all out before he sold the truck.
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  #11  
Old 02-18-2011, 02:00 PM
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Thanks everyone, I'd already torn the column apart and figured it out, haha. It is part of the ribbon and is the black one. On the connector at the bottom, it's letter "G."

I've also figured out I need to replace my turn signal switch because if I wiggle it near the bottom or tilt the column it still honks the horn. Not today, not time or nary the inclination at the moment.

I ended up hacking the horn wire, which BTW becomes black w/ white tracer on the other end of the connector at the column, using a common relay, and running my own wire out to the horns to get me by for now. I'll clean it up and do it up right and proper another time when I have time.

I don't know what the brown relay harness that had the white relay in it is in mine, all three wires to it (red, red/white trace, black) are large gauge, at least 12 awg.

Anyways, thanks all for the help!
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47 Willys
75 CJ-5
81 Scrambler
76/79/80/81/85 J20 (all the same truck)
86 Grand Wagoneer - FOR SALE!!!
96 ZJ

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You can't drink all day if you don't start in the morning.
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  #12  
Old 05-15-2019, 11:17 PM
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Old Ironsides Old Ironsides is offline
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Can't find horn Relay

I was commuting home about a month ago and suddenly an intermittent uncommanded honking cycle began. It got worse, I pulled over, disconnected both horns, and drove home. On the rest of the drive, I noticed that when I turned the steering wheel (while the radio was on) there was a slight low volume scratchy feedback coming through my stereo speakers. Thinking that grounding was occurring, I ignored it and continued home.
My truck sat about a week, and considering the possible grounding issue thought that there may be a drain on the battery. Alas, no, and I commuted to work, the truck sat for about another week, and then started fine again for the drive home.

Fast forward to today. After sitting another 2 weeks, went to drive it and 100% dead battery. Checking the voltage showed .36V. I have it on the charger now.

I checked the TSM, and it says that the horn circuit is unfused. I started looking for the relay, and cannot find it. I traced the circuitry as best I could and no success.

Questions:

1) If I pull the relay, shouldn't that de-energize the circuit?
2) Where is the relay? I could not see one anywhere under the dash, on the column or on the fuse panel. WTF, am I blind?
3) Is the horn circuit like the door lights where the positive is always live and the negative is opened and closed to energize?
4) What should I do to de-energize temporarily until I have time to troubleshoot/repair (besides disconnecting the battery)?

Cheers🍻
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  #13  
Old 05-16-2019, 12:25 PM
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rang-a-stang rang-a-stang is offline
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So all my info relates to my 79, assuming your 76 is the same.

1) Yep, pull the relay and it disables the entire circuit.
2) Mine is just kind of dangling under my dash, pretty close to the colum. Start at the steering column ribbon connector, find the black/Tr wire and follow it to your relay.
3) Kind of. Since its a 3 pin relay, it always has 12V power on one pin, the horns are on the second pin, and when you ground the black/TR wire, it grounds the coil in the relay and sends power to the horns.
4) Pull the relay. I thought there was a horn fuse but I guess not. That's about all you can do because even if you unhook the horns, the ground in the steering column is still completing the circuit for the coil in the relay and your battery is draining. The red line with 12V also feeds a TON of other circuits so you cannot unhook that.
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