Horn Button

[Mr.Chevy]

Hi,
I know this is a really dumb question but anyway I have an 87 r10 and I can't for the life of me figure out where the horn button inside the cab is.... No wires runnin in the steering wheel or on the floor beneath the parking brake?? Can someone tell me where else to look plz?
Thank you

I can post pics of that would help!

 

[1987 GMC Jimmy]

Hi,
I know this is a really dumb question but anyway I have an 87 r10 and I can't for the life of me figure out where the horn button inside the cab is.... No wires runnin in the steering wheel or on the floor beneath the parking brake?? Can someone tell me where else to look plz?
Thank you

I can post pics of that would help!

You remove the steering wheel cap and under it is the cup and some other stuff. Anyways, there should be a little nub sticking up and that's the contact that touches the canceling cam and so on. If you're having horn issues, I'd start from the simplest and go to the most complex. You have the horns and the relay to the left of the accelerator pedal that can fail so maybe check those. You can leave ground on the battery and hook a jumper wire from the bat positive to the single horn pin (unit is self grounding) and see if it blows when you tap the jumper to the horn. If it does, I'd just pull the cap off and see if that contact is showing and it moves freely, and if it is, I'd replace the relay before touching the column. It's eleven dollars.
Edit: Sorry, you do have the stock or steering wheel, right?

 

[chengny]

Start at the "convenience center" relay block.

You must be registered for see images attach

That is where the horn relay plugs in. It has 3 wires connected to it.

1. An ORN wire. It supplies 12 VDC to the positive side of the relay coil. It is also internally connected to one side of the coil's contacts.

2. DK GRN wire. This lead is connected to the load side of the coil contacts the other end runs all the way forward and is connected directly to the horns .

3. A BLK wire. This is the relay coil ground and is the one you will want to trace.

Unswitched (fused) battery power is always available to the positive side of the relay coil windings on the ORN lead. The negative side of the coil is connected to the BLK wire which is lead to one side of a remote switch.

That switch is generally located in the top of the steering column. The black lead from the coil is connected to one side of the switch's contacts. The other side of the contact set is connected to ground. Like the switch itself, the ground point is generally located in the upper section of the steering column.

When the switch is operated, the contacts are closed. This connects the negative side of the relay coil to ground. Since the positive side of the coil is always hot, grounding the negative side completes the circuit and operates the coil.

When the relay coil is energized, it pulls in and closes the contacts. As noted above, the unswitched power supply available to the coil is also shunted to the line side of the contacts. The load side of the contacts is connected to the horns via the DK GRN lead. When the contacts close the horns are connected to battery power and they beep.

So, as you can see, the only thing required - to get the horns to work - is to provide a path to ground for the coil.

There are 12 wires that connect to the convenience center. Of those 12, only 2 are black. You only need to be concerned with one of them - the smaller one. That is the wire that should be connected to the horn switch.

The problem is, the wires are all wrapped up in tape. If you want to find the hidden horn button, you will have to unwrap the tape and trace the wire. Even then, its a task because the factory wiring harness is twisted after assembly. This is done to facilitate wrapping it in the tape. It also makes the process of stuffing it into the loomed sections easier.

 

[Mr.Chevy]

Yes it is the original steering wheel...

 

[donnieray]

Great information! Especially since my horn isn't working.

 

[WFO]

Start at the "convenience center" relay block.

You must be registered for see images attach

That is where the horn relay plugs in. It has 3 wires connected to it.

1. An ORN wire. It supplies 12 VDC to the positive side of the relay coil. It is also internally connected to one side of the coil's contacts.

2. DK GRN wire. This lead is connected to the load side of the coil contacts the other end runs all the way forward and is connected directly to the horns .

3. A BLK wire. This is the relay coil ground and is the one you will want to trace.

Unswitched (fused) battery power is always available to the positive side of the relay coil windings on the ORN lead. The negative side of the coil is connected to the BLK wire which is lead to one side of a remote switch.

That switch is generally located in the top of the steering column. The black lead from the coil is connected to one side of the switch's contacts. The other side of the contact set is connected to ground. Like the switch itself, the ground point is generally located in the upper section of the steering column.

When the switch is operated, the contacts are closed. This connects the negative side of the relay coil to ground. Since the positive side of the coil is always hot, grounding the negative side completes the circuit and operates the coil.

When the relay coil is energized, it pulls in and closes the contacts. As noted above, the unswitched power supply available to the coil is also shunted to the line side of the contacts. The load side of the contacts is connected to the horns via the DK GRN lead. When the contacts close the horns are connected to battery power and they beep.

So, as you can see, the only thing required - to get the horns to work - is to provide a path to ground for the coil.

There are 12 wires that connect to the convenience center. Of those 12, only 2 are black. You only need to be concerned with one of them - the smaller one. That is the wire that should be connected to the horn switch.

The problem is, the wires are all wrapped up in tape. If you want to find the hidden horn button, you will have to unwrap the tape and trace the wire. Even then, its a task because the factory wiring harness is twisted after assembly. This is done to facilitate wrapping it in the tape. It also makes the process of stuffing it into the loomed sections easier.

I'm wanting to test the relay on the bench, before I tear into the column.
Am I right that if I supply 12v to the terminal that is alone on one side of the coil, then ground the terminal attached to the bottom of the coil, the contact will close, giving me 12v to the terminal that the contact closes on to?

 

[chengny]

I'm wanting to test the relay on the bench, before I tear into the column.
Am I right that if I supply 12v to the terminal that is alone on one side of the coil, then ground the terminal attached to the bottom of the coil, the contact will close, giving me 12v to the terminal that the contact closes on to?

Yes, the stand-alone male spade terminal supplies both the positive side of the relay's coil and also the main power to the horns (via the relay's contacts). The actual horn circuit won't be part of the test.

Looking at the relay base - not the relay block - supply the lower stand-alone terminal with 12 VDC and ground the terminal on the top left. The upper right spade is connected to the horns. When the coil is grounded the contacts should emit an audible click. If you can't hear it, just probe the upper right terminal for 12VDC. If it's hot, the relay is pulling in as designed.

 

[WFO]

I sure do appreciate it, chengny.
That's what I was thinking, but didn't want to fry the relay, and still not know if the problem was in the relay or the switch in the column.

 

[chengny]

Have you verified that the horns are actually functional? That would be the first diagnostic I would do. It would suck if you did a bunch of work only to realize that the horn diaphragms were just frozen.

Just strip the insulation back on the ends of a short piece of wire and stick one end in the bottom single socket (on the relay block) and the other in the upper left slot. That will by-pass the relay and switch entirely.

If there is no beeping/vibration...a problem exists either in the associated wiring between the relay block to the horns - or the horns themselves are frozen.

Generally all they need is a good soak with some PBlaster. Squirt it into the mouth of the horn - and loosen the tone adjusting screw. Bang it with a mallet a few times and it should start to come back to life. When/if you do get some vibration from the internals, supply it with 12 VDC and it probably will be good as new. The easiest way to get the horns out is by pulling the grille.

 

[WFO]

Just strip the insulation back on the ends of a short piece of wire and stick one end in the bottom single socket (on the relay block) and the other in the upper left slot. That will by-pass the relay and switch entirely.

Thanks again. Yeah, that's what I was planin on doin, once I knew which slot was positive to the horns, which you let me know in your relay response.
Was gone all day today, so haven't messed with it yet.

 

[WFO]

Much obliged for the help, chengny. I'm honkin now, and I can get an inspection sticker.
Relay tested fine, but nothin when I jumped at the relay block.
Pulled the grill and found the wires unhooked, which made me think the horn might've been stuck on. Jumped the battery to the horns, and they worked fine, so I hooked the wires back up.

Jumped the block again, and they honked. Plugged the relay back in, and went to the switch at the wheel. After I pulled the metal cup, I saw that the contact for the switch was recessed. Pulled it out and stretched the spring, put it all back together, and it worked fine.
I reckon that spring is wore out and will need replaced, but at least I know what it is, and it's easy to replace.

 

[Keith Seymore]

Great information! Especially since my horn isn't working.

x2. I'm going to use this info to help diagnose a problem with my '63 GP.

Thanks Chengny -

K

 

[Keith Seymore]

x2. I'm going to use this info to help diagnose a problem with my '63 GP.

Thanks Chengny -

K

Done! Horns are fixed.

Bad connection(s) at the relay.

K

 

[theblindchicken]

Should probably check the relay in my truck since the horns don't work either.

 

[Zane Murray]

Done! Horns are fixed.

Bad connection(s) at the relay.

K

So you just replaced the female in that the relay connects into and it worked? Having horn troubles myself.