VCCA Home Forums TECHNICAL - GENERAL Radios, Tools, Accessories Vintage siren wiring help

Newbie here. Got several Chevy G506, the military WWII 1 1/2 ton trucks, but that's not why I'm here. Might have to go to the fire truck board, but saw this board and stopped here.
Working on post war truck that is 24v and fellow club member wants his siren connected. Missing the data plate, so don't know what brand. 12v solren is stamped on the inside so we can connect to one 12v battery and then to a switch and then to the siren.
We took it to a local starter shop and they replaced some internal wires and tested it on 12v. We get it home and it fries our test leads. Take it back and they check it out drawing 30 amps and recommend 6 gauge wire, which is, basically jumper cable thickness. The two small terminals on this siren and the original wires that were connected to it doesn't make this thick wire make sense.
I can't see running jumper cables allover the fender and down to the switch and over to a battery. Something isn't adding up here.
I found another forum post about running the 6 gauge wire from the battery to a solenoid and then 14 gauge wires to the switch and to the siren and back to the solenoid, but I don't see how the solenoid is acting as a amp reducer.

Any thoughts on how to wire this siren up without melting wires?

I'll hang up and listen.

I just talked to a friend who is an ex fireman and who ran a business installing 2way radios, sirens, lights, etc. Although it had been too many years since he had installed a mechanical siren, 30 amps sounded low to him. I think you are gonna need the big wire.

He said they were often tripped by a momentary contact switch on the floor. They don't wail all by themselves you know, you spin them up and then let them spin back down. He did not remember whether the floor switch was heavy duty enough not to require a relay, but he has also seen dash buttons, and those would have a relay for sure.

Look into a ford starter solenoid relay if you are going to just blip it sometimes like a fireman with a second siren would, or if you are going to let 'er rip then keep hitting it like you were on your way to a fire with no other siren you'll need a solenoid relay for a snowplow. It is about the same thing as a ford starter solenoid relay but continuous duty.

You'll need the big wire from the power source to a big terminal on the solenoid relay, and another from the other big terminal to the siren. If any wires are involved in grounding the siren, they need to be just as big.

You can use small wires for your button or switch to trip the solenoid relay.

I have read about the solenoid. On my WII jeep there are 6v and 12v specific. Do I need a 24v solenoid? If I run the large wire from battery to solenoid and from solenoid to switch, then smaller wires to complete the circuit, my siren has a positive and negative two terminals, does not need to be grounded to vehicle. Am I ok with smaller wires from both siren terminals to switch? Trying to avoid having monster wire on vehicle fender to siren.

I misspoke on the voltage. Since the siren is only 12v and we are planning on picking up power off one 12b battery, not the 24v series, we will look for a 12v, 30 amp solenoid. We will run 6 guage wire from battery to solenoid, solenoid to siren and from negative on siren direct back to negative on battery. Use 14 gauge wire from foot starter switch to solenoid.

Fingers crossed. Thanks for the direction.

I would think at 30 amps you could probably get away with 8 or even 10 for the big wires. The current for the siren (because its a motor) will go way higher than than when you hit the button, but then drop. On the other hand you cant really go wrong doing what the motor shop said.

14 is probably overkill for the small wires. It wont hurt but you could go smaller if you want.

The solenoid won't care what voltage is on the large wire circuit, within reason. The button circuit is what matters. If you are using 24v on the button circuit to trip the solenoid, get a 24v solenoid. If you are using 12v on the button circuit, get a 12v solenoid.

12v 30 amp solinoid on order with NAPA. Will be in on Monday. Need to find some 6 gauge wire by the foot or I can get a 25ft roll from NAPA or find some long jumper cables and cut to length. Negative terminal on battery to negative battery terminal will be the longest run. But from under passenger seat to passenger front fender isn't too bad.

The jumper cables will have ridiculously thick insulation. I'd do something else. Automotive wire if possible, house wire (THHN stranded) if not.

Depending on where you connect the main load wire you may not need to take the ground wire back to the battery. With the main electrical system being 24v and the siren being 12v you only need the 1 battery. The easy way to connect this is to connect the siren hot wire to the link between the 2 batteries that way you can utilize the truck frame as the ground negating the need of running a ground wire.
Tony

OK, we are close, but no cookies. Wired everything up through a 12v solenoid and when we depress the foot switch to work the siren, the siren fires up, but the solenoid keeps clicking very loudly like it is constantly firing on and off. Don't know if this foot siren switch, unlike a starter switch, keeps applying direct current to the solenoid. If I bypass the solenoid, my 6 gage wires heat up, so I know the solenoid is a good idea. Just need some advice as to how to get it to reset after the initial surge protection to the siren. Again, running on 12v and the siren draws 30 amps. Siren is grounded direct to frame with ground wire and all other electrical items work fine, so frame grounding is adequate.
Any advice greatly appreciated.

If the solenoid is chattering, do something else to trigger the solenoid relay to test. Are you sure it is wired right?

Some need 12v (or 6v or 24v or whatever the trigger coil wants) from a small pin (+) to ground (-) , others want 12v (+) on one small terminal and ground (-) on another small terminal.

Make sure that solenoid relay is wired right.

If it is, then, disconnect the wires going to the switch, and try to trigger it manually with a jumper. See if the problem persists.


Not sure what you meant by that.

The switch should be a momentary contact switch. You operate these normally by holding the switch down until the siren winds up, then let go so it winds down, wind it up again, etc.

By "resetting" I meant that it sounded like the solenoid wants to keep firing when the siren switch is pressed down. I thought my starter solenoid opens when I press the starter switch and then closes back up. This siren solenoid sounds like it keep opening and closing the whole time the siren switch is pressed. I checked the volts out of the two batterys and both provide a little over 12v, although I am only picking up one battery for this 12v siren. The chattering reminds me of a starter solenoid that is running on low voltage. When your battery is running down, the solenoid works, then it chatters, then it just clicks or does nothing. The chattering is what the middle stage sounds like to me.
We wil review the solenoid wiring.

If the batteries are hot and the solenoid, more properly called a relay, chatters, then you have voltage drop between the batteries and relay, assuming the wiring is correct.
Try operating the switch with the siren disconnected.
The chattering you described happening when starting a car on a low battery is just this.
The relay pulls in, but as soon as current starts flowing to the starter the battery voltage falls so low it cannot keep the relay pulled in, so it drops out, rinse, repeat.
Wilson

Game plan for tomorrow is to run switch and solenoid with siren disconnected and see if we get chatter.
Then we will disconnect switch and connect siren to solenoid and run a jumper to see if the switch is the problem.
We picked up a 12v three post solenoid from Tractor Supply today to see if replacing the new solinois with another one will help.

More to come after testing tomorrow.

So, everything we try results in solenoid chattering. So, question...is a solenoid a solenoid? I have a 12v three post which is a internal grounded solenoid. I have used the 6v version of this up on my II jeep and no issues. Is the 0 amp draw of this siren causing an issue with the solenoid? I have had ked out at an electric shop, but I'm not 100 percent sure there could be a short But the solenoid is acting like it s through enough current for erate as it should. I could not get the 12v tractor solitor , so I just have the which is the clicking on.

Are you sure the solenoid is not defective?

Ok, so you have a 12 volt 3 post internally grounded solenoid relay, right?

You have large wire going from the 12 volt source ( one 12v battery), to the solenoid relay, and from the solenoid relay to the siren.

You have the siren grounded to the same thing (frame?) that the one 12v battery (the one that you are using for the siren) is.

You also have the frame of the solenoid relay grounded to the same thing the one 12 volt battery is.

Note: That just means they are all grounded together. Could be the frame, could be with wires, whatever, but they all have a common ground (not just wishful thinking with part of them on the frame and part on the body or something).

Do I have all that correct?

If I have all that correct, and you run 12 volts from the SAME battery source to the trigger post on that solenoid relay with a temporary jumper wire, it should work.

If it won't, there is something wrong with the solenoid relay.

Follow bloo's instructions and we can close this thread.

So, if I put my amp meter on the solinoid and get 0 volts coming out of it and then press the foot switch for the siren and get 12v coming out of it, does that mean my grounds are good? My battery negative cable goes right to the frame, but my soinoid is attached to the underside of a running board that connects to the frame and body cab. So there is a possibility I'm loosing some ground, but getting a full 12v out of the soinoid whould suggest to me that I have good ground. And, also eliminating the need for a positive test lead as I'm getting 12v out of the solinoid. I'm leahe siren itself, but don't know how to verify that. I can run a 24v hrough this same solinoid and the light will operate and I get no chatter, although I doid when the light rotates.s a 12v soinoid that I am running 224v thorugh for that test.

Always use a voltmeter to check volts. An ammeter is a dead short between the leads and can cause all kinds of havoc if you use it unintentionally. Most meters we use today do both, so make sure you are on a volts scale, and that the leads are plugged into the right hole for volts.


It probably doesn't mean much unless you already know the ground is good.



Be sure you are testing volts from the solenoid pin to the solenoid bracket. If you hit the button and you have full battery voltage checked between the small pin on the solenoid and the solenoid bracket, then your ground is ok.

The thing is you said the solenoid wasn't staying on solid. That is going to make it almost impossible to just check with a meter.

I would run a ground wire from that solenoid relay bracket down to the frame. It doesn't need to be like the big siren wire. It is only carrying the same current the button wiring is.

Follow bloo's instructions and we can close this thread.

I didn't realize that this was a priority for this forum. Please, feel free to close it at any time.

I think he'd just like to see you get the problem with the siren solved. No big rush around here as far as I know. :)

No rush, no problem, we are just trying to help you solve the siren problem.