How to wire a mechanical siren

Paul Steinberg

Staff member
Super Site Supporter
These instructions are for wiring a siren that will wail using the horn ring. It will also allow you to choose between the horn and siren with the flip of a switch.

Parts needed:

Cole Hersee 24047 Intermittent duty solenoid and 1 DPDT (ON)-OFF-(ON) 3 Position Toggle Switch AC 250V 15A. Appropriate length of #2 or #4 insulated copper wire. I prefer welding cable, since it is easy to work with, and bends easily. I also buy terminal ends with the solder slug in them, and install the ends by heating them till the solder melts, and inserting the bare copper into the solder. Tape or heat shrink the end of the terminal, so it looks neat. Don't forget that the heat shrink wrap goes onto the wire before you make the terminal end connection.

Next, locate the wire that comes down the steering column that controls the horn. This wire is usually black, and it will blow the horn when grounded. You will be cutting this wire, and the end from the horn ring, will go to the center terminal of the 3 position switch. The other end of the cut wire will go to one of the end terminals of the 3 position switch. STOP and check these connections, by blowing the horn. It shouldn't blow when the switch is in the neutral (middle) position, or in the position that doesn't have a wire attached to it. Only when the switch is pushed toward the end that has a wire attached to it. If the horn blows, you have completed half of this horn wiring project correctly. Now, add a wire to the other terminal of the switch that until now hasn't been used, and run this wire out to the engine compartment. I suggest using 14 gauge wire, of any color you want, as long as it is black. Black wires are usually ground wire, and this wire will be the ground for the solenoid. The Cole Hersee Solenoid will be mounted somewhere that is convenient, and determined by the installer. The new black wire will be going to the small negative terminals on the Cole Hersee switch. Now, we need to power the Solenoid, so if your fuse block has a blank fused opening, connect a 14 gauge insulated copper wire to that and run it out to the solenoid, and it will be attached to the small positive terminal. Now, we need to cut into the positive battery terminal, or pick up power somewhere that is going to be connected to the large terminal of the solenoid. I suggest a multi stranded copper wire #2 or #4, depending on the size of the siren. This wire will need to be measured carefully, and have the proper connection terminals attached to it. Usually a auto parts store like NAPA can make this wire up for you. I like to take the power for the siren directly off the starter solenoid large terminal. Now, if you have followed all this, you will know where 3 of the wires go on the solenoid, and where they are coming from. The 4th wire, goes from the other large terminal on the solenoid, and goes to the siren. Depending on the type of siren will determine the size of this wire.
Check all connections for sharp bends, and the possibility of getting cut on sharp edges of metal. These are general instructions, and are for informational purposes only. If you don't do it correctly, and you let the smoke out of the wires, or Sir Lucas, the prince of darkness visits your car, I will not be responsible. In all seriousness, if you are not experienced to do this work, then print these instructions, and have a qualified electrical technician do the work for you. Estimated time to complete the task is about 3 - 4 hours, if you have everything in advance. If you have to start searching out supplies, and an extra day or two. If you are old like me, then it will take you considerably longer.

Things not mentioned in these instruction, such as finding a suitable location to mount the 3 position switch, will require you to determine this on your own, depending on your personal preference, and ease of installation. The same goes for locating the Cole Hersee switch. In short, you will need to figure out a few things on your own. If you get stumped, post your questions below, and I will offer you additional assistance.

Have a topic that you would like help with, post it in the technical forum, and it will be answered by one of our technical advisors.


  • s-l500.jpg
    24.9 KB · Views: 348