Adding a Horn relay

[EastYorkStang 63]

Has anyone put in a relay in their ‘70 for the horn ? 

On mine I blow fuses. I’m running a Grant steering wheel which I think is the reason. 

[aslanefe 333]

46 minutes ago, EastYorkStang said:

Has anyone put in a relay in their ‘70 for the horn ? 

On mine I blow fuses. I’m running a Grant steering wheel which I thing is the reason. 

RPM's post on this thread describes how to install a relay for the horn, but don't know if 69 and 70 are the same.

[RPM 1,190]

Ya, Grants and Mustangs don't jive. I do know the relay instructions work for 1965-69, so...

[EastYorkStang 63]

Quote

What wire should I be looking for ? Regardless of colour ?

 

[RPM 1,190]

I'd figure the yellow wire is listed as the horn in the schematic/drawing from Ford. You'd need to research that. But since it's the only big yellow wire in the steering column it isn't hard to find. 

[Midlife 814]

The yellow wire is the input power line for the horn button; the output is typically a blue/yellow wire.

[nymustang1969 22]

I put a Bosch style relay under the dash in my 69' for the horn. Midlife is correct on the color codes for the wiring. I tapped into the yellow wire for the input power to the relay. I then cut the blue/yellow wire under the dash after it comes down from the turn signal switch. The blue/yellow wire on the switch end is used to trigger the relay, the other end is to the output of the relay to feed the horns. I have a rimblow switch, and this works very well because it takes the load of the horns off the switch. The relay now handles the heavy current.

[danno 128]

I did it also.  The horns would start with a normal sound, and a tenth second later would be a sick buzz like an alarm clock. They were not getting enough current through the horn switch and wires.  I added a relay at the horns, like the headlight relay.  

[Mach1 Driver 560]

If the slip ring on your aftermarket wheel doesn't line up with the steering column then adding a relay won't solve your problem. Many of aftermarket wheels are made for GM cars and don't match Ford columns. GM is a bigger market. Before adding a relay I would check the position of the slip ring track in relation to the contact button. The button is probably slipping off the track and shorting to ground, and since it is hot that takes out the fuse. Also you could check the amp draw on the horns- it should be around 13.9A for both.

[EastYorkStang 63]

What is this slip ring you talk about ? Grant # 1150 is what I have. 

[Mach1 Driver 560]

Its a bit difficult to make out which is the actual slip ring in the first picture, but its a round track on the back of the steering wheel that the contact button rides on, and is about in the middle. The contact buttons are on the top of the column and spring loaded. One is being measured in the second picture. Even with the stock parts, the horn contact buttons don't ride in exactly the middle of the ring. I suppose that's because the column is used on everything from Lincolns to Mercurys, and they also had to work around the turn signal switch. I don't recall if there are actually two rings and two buttons, or just one- it looks like there could be two- an innie and an outie. That is power in, through the rim blow switch and back out to the horns. I see what looks like a second contact button above the caliper. I do remember laying out the tracks in CAD and finding that none of the aftermarket columns match the slip rings on a Ford wheel, so if someone wants to use a stock wheel you need a Ford column. I have no clue what is going on dimensionally with a Grant wheel.

..

[dream car 12]

I have stock horns and rim blow steering wheel.  I placed a relay between the radiator support and  the battery, hidden from sight, without do any cutting to the stock wiring.  Unplug the female horn connector insert a male blade connector, connect the other end to the relay.  From the relay run a wire with blade connector, and plug into horns, From the relay run a short wire to the starter relay, place a inline fuse for safety. The horn work great now, before the relay it sound so goofy I was embarrassed to honk the horn.

[danno 128]

21 hours ago, dream car said:

I have stock horns and rim blow steering wheel.  I placed a relay between the radiator support and  the battery, hidden from sight, without do any cutting to the stock wiring.  Unplug the female horn connector insert a male blade connector, connect the other end to the relay.  From the relay run a wire with blade connector, and plug into horns, From the relay run a short wire to the starter relay, place a inline fuse for safety. The horn work great now, before the relay it sound so goofy I was embarrassed to honk the horn.

I did pretty much the same thing.  Added it to existing wires and hooked it up just like the headlight relay.    Looking back, it would have been better to add it with the headlight relay, it would have been easier. 

[EastYorkStang 63]

I’ve got the steering wheel off the car now. 

If I disconnect the horns and press the horn button the fuse should blow. If I get what you’re saying about the buttons grounding out ?

On 8/9/2020 at 7:05 AM, Mach1 Driver said:

Its a bit difficult to make out which is the actual slip ring in the first picture, but its a round track on the back of the steering wheel that the contact button rides on, and is about in the middle. The contact buttons are on the top of the column and spring loaded. One is being measured in the second picture. Even with the stock parts, the horn contact buttons don't ride in exactly the middle of the ring. I suppose that's because the column is used on everything from Lincolns to Mercurys, and they also had to work around the turn signal switch. I don't recall if there are actually two rings and two buttons, or just one- it looks like there could be two- an innie and an outie. That is power in, through the rim blow switch and back out to the horns. I see what looks like a second contact button above the caliper. I do remember laying out the tracks in CAD and finding that none of the aftermarket columns match the slip rings on a Ford wheel, so if someone wants to use a stock wheel you need a Ford column. I have no clue what is going on dimensionally with a Grant wheel.

..

 

[Mach1 Driver 560]

12 hours ago, EastYorkStang said:

I’ve got the steering wheel off the car now. 

If I disconnect the horns and press the horn button the fuse should blow. If I get what you’re saying about the buttons grounding out ?

 

Ah.... no, with the steering wheel off, nothing is connected. I've reviewed a couple more pictures. The two contact buttons I referred to are both shown in the second picture . They are spring loaded and sticking up from the column. The dial caliper is measuring the lower contact button, and the upper button is slightly to the right an a little above the calipers. There are two slip rings on the steering wheel and they are each electrically isolated from the wheel.

Power comes  from the battery to the light switch, through an internal 15A circuit breaker and out light switch terminal "A" to the steering column, to one of those contact buttons sticking up. When the steering wheel is in place the contact buttons push against the two circular slip rings shown in the first picture. It may appear there are three rings in the picture, but the center one is the hub to hold the wheel on the column, then there is a slip ring in the middle and another outboard of that. So power comes in through one contact and slip ring. A wire on the other side of the steering wheel connects to the slip ring and goes to the "rim-blow switch", and back out to the second slip ring, through the other contact button and to the two horns.

What happens with aftermarket steering wheels is that the slip rings do not line up with the contact buttons sticking up from the column. The contact buttons are spring loaded, and if they fall off the track of the slip ring they contact the body of the steering wheel which is grounded. That causes a direct short and that trips the circuit breaker in the light switch.

[EastYorkStang 63]

Thanks for all the help. Decided to install the factory wheel. 

[dream car 12]

EastYorkStang; Glad you found out the problem, relay is still the best way to hook up a horn.  It deliver the max voltage to the horns. 

[EastYorkStang 63]

Totally agree. Needed a fix so I could drive the car. Looking now into making a power point or terminal so I can put more relays in place. Only so much I can put on the solenoid.

[dream car 12]

Here are two product you can try.  The breaker have long studs bolt, you can attach multiple terminal to it. also build in breaker for overload.

https://www.amazon.com/Ampper-DC-12V-Automatic-Automotive/dp/B07WC9LB7L/ref=sr_1_5?crid=OYEKD3B4F80P&dchild=1&keywords=30+amp+auto+reset+circuit+breaker&qid=1601382485&sprefix=breaker+auto+30%2Caps%2C168&sr=8-5

https://www.amazon.com/Kohree-Waterproof-Negative-Indicator-Automotive/dp/B07XXTQPKL/ref=sr_1_3?crid=6W6LONM094UW&dchild=1&keywords=12v+battery+terminal+fuse&qid=1601382606&sprefix=terminal+fuse+12%2Caps%2C173&sr=8-3