Hi All,

Please bear with the dumb question.
I am in the UK and have just got hold of a 74 360 F100. I have ordered the manual but it is on a 3-6 week USPS delivery :0(

SI need the horn to work to get through the annual inspection but it doesn't so..

The actual horn unit works..
I have removed the metallic strip switch on the wheel and have 12v at the wheel contact.
The relay looks good and my wiring is as follows from the relay.

Brown brings 12v from the battery, it goes through the realy coil and delivers 12v through the blue wire to the wheel.
The yellow/green wire from the relay would take 12v to the horn if the relay closed.

So the question... If i then take a wire and earth the wheel supply (presumably as the metal strip switch would do) the relay should close and supply the horn, unfortunately I get absolutely nothing!

Can anyone give me a clear way forward, i.e. does the relay need a ground etc?

Is my wiring correct..

Regards - Paul
Regards - Paul

 

I had the same problem with a 77 F150. I ended up putting a jumper across the rubber coupling at the bottom of the steering column under the hood. The trouble was that the steering column shaft lost its intended path to ground. By putting the jumper on I gave the steering column a new path to ground. I wouldn't recommend that you leave it this way because after doing this everytime you use your horn the current for the relay will pass through the bearings in the steering box. This is not good for the bearings. It will get you through inspection thou.

 

> does the relay need a ground etc?

Yes, without it it can not create a magnetic field to energize the circuit.

If there is only one wire to your horn (should be a yellow wire under the hood), then make sure the bracket of the horn is grounded.

 

>> does the relay need a ground etc?
>
>Yes, without it it can not create a magnetic field to
>energize the circuit.
>
>If there is only one wire to your horn (should be a yellow
>wire under the hood), then make sure the bracket of the horn
>is grounded.
>


I have a ground to the steering column, my horn is also well grounded and I have just had the relay tested and it works.....!

So I'll try it again tomorrow as it looks like everything is ok, but... it just doesn't work at the moment..

Thanks all so far..

 

>I had the same problem with a 77 F150. I ended up putting a
>jumper across the rubber coupling at the bottom of the
>steering column under the hood. The trouble was that the
>steering column shaft lost its intended path to ground. By
>putting the jumper on I gave the steering column a new path
>to ground.

Right, this is definately my problem... I have a path to ground..just not a good enough one for the relay to operate. I have now operated the horn by grounding the horn 12v to the interior light door switch, not too handy when on the move!

So I have looked at the column and shouldn't the retaining bolts through the coupling give a ground? I can't seem to get any decent ground anywhere around their either, anyone know how easy it is to ground the steering shaft in the cab?

Regards - Paul

 

hi
Look on the engine side of the firewall where the steering collom goes through there is a flexible coupling on the collom to the steering box connect a wire on one of the bolts/nuts facing the firewall and the other side to the bolt/nut facing the steering box this should ground the collom
Hope this helps it did on my 78 F250
Regards Chia

 

> I can't seem to get any decent ground anywhere around their either

First make sure the cab is grounded from the battery. Then (at least in my truck) use the bolt that holds the emergency brake assembly to the dash board. This is close to the column and you can run the ground wire up under teh dash where it can not be seen.

 

 

What did you attach to on the column? I'm about to lose my mind trying to get ground to the horn of my '74 Bronco. Strapping the rag joint did not fix the problem.

Thanks,

Lee

 

How do you do this? Do you mean "Ground the battery to the cab?"

 

Sorry, my question was for rebocarbo also: How do you tie into the column, and will this ground the shaft itself?

Thanks,
Lee

 

> How do you tie into the column, and will this
> ground the shaft itself?

To answer this (though I have never owned an early Bronco) and the earlier question, which I missed.

How I like to ground all my trucks like this since I hate hard to track down problems.

(-) Marine terminal with a 3/8 stud on top with a brass wing nut.

run (4) pieces of 4-6 gauge wire to:

alt. bracket
(if EFI I also run another directly to engine intake manifold)
engine
frame
cab
10-12 gauge wire directly to voltage regulator

On EEC/EFI I run one to the exhaust since the factory ground straps (cab to exhaust) tend to rust away and drop off.

On the cab ground wire, I try to find a bolt or stud sticking out that really is not coming off anytime soon that will provide a good ground for the whole cab. Stud for heater core (kill two birds with one stone) , wiper motor, or the bolt sticking through the firewall that is holding the dashboard on. I sand the cab area down to shiny metal, put a lot of silicon grease on the cab side, put on the ground strap with anti-seize on the nut. Then cover it all in grease. If I am worrying about it washing off, I put a plastic cap on it.

As for the in- the-cab ground, especially on trucks with metal dashes, I like to use the emergency parking brake located on the floor. The bolt/nut holding the bracket to the dash is hidden from view, the brake assembly is metal and connects itself to the cab in many places. Also, it is a handy position when running wires down from the headliner, through the door, under dash alarms, and from the steering column.

To attach to the steering column on a collectable Bronco I would probably drill a tiny hole where it can not be seen on the column (under dash on the top of the column), insert the wire, and solder it to the column. Then attach to the bolt holding the emergency brake to the dash with an eyelet connector.

Or I would use a small bolt on the column sticking up like a stud from the top and put a connector on that. On some columns you can run a wire to a small push on clip, but, these tend to rust over time or fall off.

 

I'm going to try wiring the emergency brake screw to the column, and hope that gets ground to the shaft. This is very frustrating since I can jumper the horn button contact to: the shift lever - BEEP!, the signal lever - BEEP!, any screw on the dash or door - BEEP!, but jumper to the steering shaft - NOTHING!!! (but sometimes beep) Even after strapping the rag joint.

Thanks for the tip.

 

I had to make a ground jumper that goes from the bolt on the north side of the u-joint to a bolt on the south side of the rag-joint (about 2ft ?). I used 3 cable ties around the wire and shaft to hold it snug and all seems to be working fine. I wish I knew why this is now required - this truck has 48K miles and very little rust - I'm not sure what is different now from 1974 when she rolled off the line. The factory grounds appear to be good. It is factory wired from the negative post on battery to fender, then to alternator, then to engine block.

 

I know it's been a couple of months since you originally posted this question (you might not even be monitoring this thread anymore...) but I managed to "fix" my broken horn in my '74 F100 yesterday.

Dinking around under my dash yesterday on an unrelated task, I happened to ground an unused pin in my "14-pin connector" and "HOOOONKKK!" Sweet! But there was no loose female connector that should have attached to said "open pin" under the dash.

So without a super quick solution available (reattaching a loose female pin) I just rigged up a push button on the dash that attached to the unused pin, allowing it to ground out and causing the horn to sound.

Granted, the horn button on the steering wheel still does not ground the circuit (which would be ideal). But until I find the mystery female pin which should attach to the 14-pin connector floating around under my dash, at least I have a provisional horn. Maybe you can do the same.