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Josh Gentry
10-02-2009, 07:31 PM
I wired up my Federal 28 on my 67 MM, All I can get it to do is when I flip the switch on, the horn comes on. Anyone know whats wrong?:confused:


Thanks
Josh

Todd Merrifield
10-02-2009, 08:37 PM
Start by double checking your wiring against the diagrams on this page (Thanks to Kevin O'Connell):

http://www.siro-driftsirens.com/diagrams.html

John ED Renstrom
10-02-2009, 11:33 PM
pay close attention to the way it's wired for the horn siren switch. in order to get the horn to come on when you throw the switch you have to be grounding out the horn relay. the horn works by grounding out the wire going up the steering wheel. that would be spliced on the horn-siren switch so that one way you ground the horn relay the other the siren relay when you press the horn button on the wheel. so if I'm think right wire from the horn relay and wire from the siren relay go to different legs of the switch. the one going up the steering column goes to the other. so that all your switching is the ground wire from the relays when you touch the horn ring you ground out the relay the switch is closed on. if you turning the switch and the horn honks it because your grounding that leg that should be open to the horn button. bad switch, wire that is grounding threw a brake in insulation something like that.

Josh Gentry
10-03-2009, 02:34 PM
Its a 3 Way switch, up is siren, middle is off, and down is horn. There is 1 wire ran for each posission, I would think 1 of them shouldn't have a wire?

Josh

Paul Steinberg
10-03-2009, 03:13 PM
The middle wire is the common wire that connects the horn wire in the steering column to the switch. The other two go from the switch to the horn blowing solenoid or the siren solenoid. If you don't understand electrical wiring, then I suggest that you leave this to someone that does, and can teach you. Always keep it in mind that if you mess up with electrical wiring, the most disastrous thing that can happen is that you get to watch your car go up in smoke. Even though it is low voltage doesn't mean that you can't cause an electrical fire from mis-wiring.

John ED Renstrom
10-04-2009, 12:35 AM
most are only a single pole double throw switch. 3 legs a wire on each as Paul descriped. if your horn honks one way and nothing the other, then the switch is most likly bad. I have never seen one with a off. I would say some one has changed it at some time using what ever was on hand.

Todd Merrifield
10-04-2009, 01:02 AM
I would also strongly suggest you have someone look at it that knows what they are doing. That being said, with the type of switch you describe this is one way it might work: It could be set up so that the power (or ground) wire from your horn button goes into the switch in the middle position. Then, the other two wires go out to our horn and the siren relay, like Paul said. When you have the switch in one position and you hit the horn button it honks the horn. When you have the switch in the other "on" position and hit the horn button it activates the siren. All it is doing is taking the power to run one thing and switching it so that it runs something different.

But, since niether position activates the siren there has to be something wrong somewhere else in the system. I would also think that the switch shouldn't activate the horn by itself either, so the switch may be wired wrong as well.

You really need to have it looked at by someone who knows their way around a cars electrical system. Or talk to Dwayne, since I think he was working on getting a Federal 28 wired up in that car as well. I don't know if you got his siren with the car or not, but he may be able to add to this discussion.

Paul Steinberg
10-04-2009, 11:35 AM
GM uses a grounding method of activating the horn through a isolated ground horn relay switch. There should be another isolated ground relay that the siren is hooked to, and on the other side of that relay should go to power. The way that GM designed the horn blowing circuit is to allow the horn to be blown even if the key is not in the ignition switch. In fact, this is the way that Ford & Chrysler also wired there cars. It isn't rocket science to figure out these systems, but it does take some detective work to find the wires start and end locations. It is a strong possibility that the car was never totally wired for a siren. It might be that the wire is only leaving the switch and ends a few feet under the dash. This would have been done this way to accommodate an electronic siren module. If it were wired for a mechanical siren, then the wire would continue out under the hood and terminate at a solenoid switch.

Paul Steinberg
10-04-2009, 01:28 PM
I have a feeling that there are some people that don't fully understand how this circuitry works, so below is an explanation and picture...

A solenoid is an electro mechanical switch that has the ability to transfer high amperage power from one side to the other. It is either a grounded switch that you apply power to operate, or an ungrounded switch that you switch either both the power and the ground, or just one side, depending on application. An example of a solenoid on a car is the part that is mounted between the battery cable and the starter motor. Starter motors need high amperage to operate, so there is a solenoid (switch) mounted between the wire that connects the battery to the starter. This solenoid is controlled by the ignition switch. You turn the ignition switch and it sends a low amperage current to the solenoid. The solenoid then closes, and connects the two high amperage wires together.
Pictured is what is commonly referred to as a ungrounded solenoid. On the two ends, you would connect the terminal from the battery, and on the opposite side, you would connect the terminal end that comes from the wire that is connected to the mechanical siren. The two smaller terminals in the center of the solenoid are the positive and negative terminals. One will be switched, and the other will connect directly to the opposite pole. i.e. If you switch the hot line, then the other will be connected to ground. If you switch the ground (negative), then the other wire will have a hot feed (positive) connection.

http://www.postimage.org/Ts1Uybcr.jpg (http://www.postimage.org/)

Paul Steinberg
10-04-2009, 05:48 PM
Further explanation .............. below is a dialog that I had by PM with a member....

What exactly does a solenoid do...what's its function in a siren wiring project, please?

a solenoid is an electro mechanical switch that has the ability to transfer high amperage power from one side to the other. It is either a grounded switch that you apply power to operate, or an ungrounded switch that you switch either both the power and the ground, or just one side, depending on application. An example of a solenoid on a car is the part that is mounted between the battery cable and the starter motor. Starter motors need high amperage to operate, so there is a solenoid (switch) mounted between the wire that connects the battery to the starter. This solenoid is controlled by the ignition switch. You turn the ignition switch and it sends a low amperage current to the solenoid. The solenoid then closes, and connects the two high amperage wires together.

I'm still in the dark. If it transfers high amperage from one side to the other---why is it necessary? Why not just let the current flow straight to the siren (thru a switch). In other words, what would happen if you wired a siren without a solenoid? Thanks

If you were to run the siren through the switch, the switch would burn up, since it is only rated for about 20 amps, and most mechanical sirens draws 50 - 75 or more amps, depending on model. There are some sirens that draw less amperage, however, even the smallest siren will probably draw more than the average dash switch can handle with few exceptions. You also have to realize that if you were to use the switch, even if it were designed for higher amperage, you would need to be turning it on and off to get the desired results, and usually a switch isn't mounted in a location that is convenient to operate multiple times while driving. This is why the horn ring is used to switch the siren on and off through the solenoid. There are some floor switches that are capable of handling the high amperage requirements of the siren, however, they present other problems, such as routing heavy copper cables to and from the floor switch. Most of the floor switches that I have seen installed switch the solenoid for convenience. Also keep in mind that switches are designed to be used intermittently, and operating a siren through a mechanical switch just isn't practical, or convenient.
An example of a switch that can handle the higher amperage is the Cole Hersee battery transfer switch that is commonly found in fire trucks and ambulances with dual batteries.

My experience with this stuff is from the 1960's funeral home ambulance I worked on. By 'switch' I meant push button (dash, floor). So the solenoid allows only momentary bursts of high amps thru the switch, just enough to spin the siren motor (or starter motor), right? And if you held down the dash mounted siren button too long, the switch would still burn up, right?

What you have experienced with a dash mounted push button switch, or floor mounted foot operated switch, was exactly what I have described. It was connected to the solenoid under the hood. Most people never understand what is actually happening when they push the button, only expect the siren to work when they do so. Solenoids are not new, and have been around since the 1930's. It is like the switch that operates the heater blower in your car. You move the switch, and it connects to a relay (solenoid) and turns on the blower motor. You are not aware of the relay, nor do you care. All you want is to have heat. When it no longer works, you assume that the switch has gone bad, but it actually is the relay that has gone defective. Change the relay and it works the way that it originally did. The switch itself never carries any high amperage, only enough amperage to activate the solenoid.

Todd Merrifield
10-04-2009, 09:45 PM
I first encountered relays in my car electronics installing days, during alarm install training. For whatever reason, I simply could not wrap my head around how a relay worked, for about two days. People tried to explain it to me but I just couldn't understand. Then a light went off in my head and I understood. After I figured it out I couldn't believe that I couldn't understand it before, it was so simple.

At its base level, a relay (or solenoid, basically the same thing, just bigger) is just a small switch working a bigger switch. It allows you to use a minimum amount of voltage/current to switch a bigger amount of voltage/current. This is done by an electromagnet. What happens is you apply power through the switch to the electromagnet, and the electromagnet pulls down a metal "leaf" that bridges the space between two contacts. When the two contacts are joined, the power flows to whatever the solenoid is hooked up to.

Perhaps the best example to help people to understand is their automobiles starter solenoid. When you turn the key to start your car, the battery cable isn't hooked up through the ignition switch, it is hooked to the starter solenoid. When you turn the key, you are activating a much larger switch somewhere else to actually spin the starter. In fact, starter motors and siren motors are very similar in the way they work and the current they draw. When you press the button to activate the siren you are activating a solenoid much like the starter solenoid when you start your car.

Josh Gentry
10-05-2009, 03:33 PM
All the wires were already run except for the siren cable whitch I put on, and the solenoid had ben taken off, and I put another one on it. In the down posission, the horn works when you press the horn button on the steering wheel. In the middle posission, theres nuthing. In the up posission, the horn just comes on. Paul, Jeremy is coming over some time this week, we're gonna figure this thing out. Between me and Ledford, theres no telling what my car will be doing when you turn on the switch.:rolleyes:

Josh

Paul Steinberg
10-05-2009, 04:47 PM
Not all solenoids are created equal. You have something wrong in the wiring. Nothing should work in the middle position, in fact, there shouldn't be a middle position. You have the wrong switch to start with, and that might be the whole problem. Without being there to see it myself, I can't help diagnose the problems any further. I am available on an hourly consulting basis. :D

Bruce Osborne
03-29-2010, 09:01 PM
This assistance was very clear & well witten.