Horn Kit Alternate Install Page

About this method:

If you have a good working horn system on your bike, you'll likely just plug in the male spades on the Horn Kit to your old Horn wires. In this case, this page does not apply to you. Go here to see the Regular Installation Page.

This method is only for bikes without a good working horn system, using a Posi-Lock and a Posi-Tap to connect directly to the bike's wiring instead of plugging male spade terminals into the old horn wires.

This could be for custom bikes, ATVs with no horn system, or just an old bike with horn system problems or a nonfunctional horn system.

You will need a wiring diagram and the ability to identify your bike wire colors and function.

You may need to add a horn button to your bike. You basically need a momentary SPST pushbutton switch that is attached in an easy to use location. Companies specializing in after market equipment for old British bikes are a good place to find such a horn button.

If you have a real old bike and you can't salvage the existing horn button, a new switch cluster is impossible to find, or a replacement switch cluster is just too expensive, adding a separate horn button might be the answer.

And of course if you're building a custom bike from the ground up, or rewiring an old bike you can use this method of attaching the Horn Kit to your bike.

Installation:

Wiring diagrams see here.

The Horn Kit puts battery power directly to a pair of horns (or single horn if the Single Horn Kit). The trigger leads plug into your existing horn wires. And the battery leads attach to the bike's battery posts. The horn leads plug onto the horn(s).

Please read and understand these instructions fully before proceeding with installation. Take the kit and instructions out to the bike and identify everything first, while reading these instructions carefully. Check, identify, and verify your bike's wiring well.

If you have difficulty understanding any of these instructions, maybe you should ask an electrically savvy friend to do the work with you.

Things you Will Need:

- Philips screwdriver and wrench - to remove and reinstall the battery wires.

- VOM or test light

- your bike's wiring diagram

- wire cutter and stripper

Things you Might Need:

- Service manual - Clymer, Chilton and Haynes produce manuals for many motorcycle models. Your dealer may be a good source for these. A manual is not necessary, but it will make things easier, especially if you need to remove parts to get at your horn button wiring.

- Any other tools needed for gas tank removal, etc.

- An assistant will be valuable to help you hold things during the tests below

Preparation and Identification:

You will remove your bike's gas tank to mount the relay and route the wires along the frame under the tank. You'll need to identify and connect to wires which are likely under the tank, but might be in the headlight shell on some bikes. You'll also need access to the battery. Before starting, remove the battery negative lead(s) to disable the bike's electrical system. Leave the positive lead connected for now, as you may have to reconnect the negative lead for testing later.

Remove the screw (bolt) holding the wire(s) onto the negative battery terminal, being careful not to lose any nut on the other end of the screw (bolt). Bend the wires away from the battery to make sure they won't touch the negative battery post during your installation. Tie the wires back if necessary to keep them away from the negative battery post.

Connecting the Horn Trigger Leads:

Normal Grounding Horn Button System:

On most bikes, the horn button normally grounds the horn, or horn relay. If yours is the opposite, in that it powers the horn or horn relay, then skip this section and go below to the Alternate System section. Study your wiring diagram to find out which system you have.

You will need to find an ignition switched wire that is powered at all times when the ignition is on. The flash to pass wire is usually powered when the ignition is on. This is a good wire to use to tap for switching power. The relay uses a mere 1.8 watts of power so you won't be putting a large load on any wiring you tap.

Wire 1 (red) - Once you've identified an ignition switched wire you can connect the Kit's red trigger wire to it. I suggest using a Posi-Tap in order to make a good connection and not damage the wire. The ignition switched power wire you choose to Posi-Tap can be anywhere that the Kit's red trigger wire will reach. This Kit will draw a very low current through this Posi-Tap so you don't have to worry about overloading the wire. There is usually a switched power feed on the left switch cluster, as well as the horn button's wire. This makes it easy to connect the Kit's blue and black switching wires close to the location of your relay under the tank. See your bike's wiring diagram to decide where to connect.

Wire 2 (black) - Connect the Kit's black trigger wire to the wire leading to the horn button. I suggest you cut this wire from any other connections and use a Posi-Lock to connect it to the Kit's black trigger wire. The Kit's black horn button wire must connect the horn button which then completes the ground circuit when you press the horn button. You must cut the horn button wire and then Posi-Lock connect to it, to ensure that the Kit's relay won't be grounded by any other means than when the horn button is pressed. Don't leave any other connections to the horn button when installing this way. Any exposed wire that you cut but aren't using, should be well protected by folding the end back, taping well, and adding a tie-wrap to secure the tape.

Note that you'll have to cut off the Kit's male spade terminals, strip the wires and then connect. I suggest using a Posi-Lock for the black trigger wire, and a Posi-Tap for the red trigger wire.

You can skip the next section.

Alternate Powering Horn Button System:

Note that a horn button normally grounds the horn relay, although some bikes have an alternate system where the horn button supplies power to the horn or horn relay, which is already grounded. If your bike uses this system on the horn button, you connect the trigger wires for new Relay of the Kit a bit differently.

NOTE:There are two trigger wires on the Kit's Relay. It doesn't matter if you connect either one to positive, as long as you connect the other one to negative. The Relay is not polarity sensitive. However, to stick to conventions, I suggest you connect the red trigger wire to the positive and black to negative.

Wire 1 (red) - You will connect the Kit's red trigger wire to the wire coming from the horn button. You should test that the wire you choose does supply current when the horn button is pressed.

Wire 2 (black) - Connect the other trigger wire to any good ground.

Note that you'll have to cut off the Kit's male spade terminals, strip the wires and then connect. I suggest using a Posi-Lock for the red trigger wire, and a Posi-Tap for the black trigger wire.

Before Proceeding:

Removing Old Horn and Wiring: If you are removing an old horn and installing by this method, you should carefully cap the wires that connected to the old horn. You might want to do this if you want to leave all the original wires in place. You don't have to remove an old horn relay, but if you want to, you will have to follow your wiring diagram and cap the main power wire leading to the relay from the horn fuse.

Wire Colour Codes: The wire colours on the wiring diagram below use short forms for the German colour names. Every wiring diagram should have a colour chart listing the colour codes used on the diagram.

WARNING! Make sure you identify the wires by their proper colours. Try and get a wiring diagram with colour codes in your native language, if possible.

Typical Wiring Diagram (BMW K75) Showing Horn Circuit. (Some details changed for compactness.) Note the kit is shown at the top of the diagram below.

Connecting Your Horn(s):

Route the Horn Lead wires carefully up to the horn(s), and plug them into the correct terminals as marked on the horn(s). (black wire is negative, blue is positive) With the Horn Dual Kit you now have a choice of keeping the entire length of wires and tying them up somewhere safely, or shortening the leads to length and reattaching them to their Posi-Locks near the relay.

In all cases, make sure you have the wires carefully routed and tie wrap them up from the horns back to the relay, so they are not hanging down or rubbing anywhere when the handlebars are moved all the way from side to side. Be particularly careful in routing the wires up past the steering and forks, that they are not pulled or pinched when the handlebars are fully turned to either side.

Note: Horns need some kind of special mounting that is not rigid but allows the horns to vibrate a bit. Make sure you have the proper mounting brackets for your horns. Read your horn instruction manual carefully to locate and mount them before running the wires to them.

Relay Installation:

Before tie wrapping all the wires on each side of the relay, decide on a location under the gas tank for the relay. You can bolt it into place using the mounting tab, or tie-wrap it in place. It should not move or disturb other bike components. Carefully route and tie-wrap the wiring under the tank from the relay all the way back to battery. Usually you can follow along next to the existing wiring on the bike and tie-wrap everything carefully into place. Make sure the wires will not be rubbed anywhere. Make sure no wires are pinched between something like the gas tank and the frame.

Battery Wiring Installation:

- You should already have removed the battery negative lead(s) as instructed at the top of this page. The Kit is shipped with two fuses in the bag, but none installed in the fuseholder. DO NOT install a fuse yet!

- Remove the screw (bolt) holding the wire(s) onto the positive battery terminal, being careful not to lose any nut on the other end of the screw (bolt). Clean all connection surfaces with fine sandpaper and check the condition of all existing terminal(s) and wire(s) you removed, including the battery post and the screw (bolt) and nut.

- Replace all Positive wire(s) together with the M6 ring terminal on the kit's red wire (near the fuse holder), onto the positive battery terminal with the bolt/nut/screw. Tighten the screw (bolt) securely.

- Clean all connections on the negative battery post and terminal surfaces with fine sandpaper and check the condition of all existing terminal(s) and wire(s) you removed, including the battery post and the screw (bolt) and nut. Now is a good time to find a loose battery post or almost broken terminal, if there is one.

- Replace all negative wire(s) together with the M6 ring terminal on the kit's black wire (last wire not connected), onto the negative battery post with the bolt/nut/screw. Tighten the screw (bolt) securely.

The wiring around the battery area should now be tied up neatly with the fuse holder accessible.

This is a good time to check your battery's fluid levels and top up if needed. As always, familiarize yourself with everything in the area. You never know what the previous owner might have done.

Caution! Do not put a larger than 20 amp fuse in the kit. If you blow this fuse, you have a problem. Please contact me if you need help. Do not install the fuse in the kit until you read and do the Final Check below!

Final Checks and Testing the Installation:

Final Check: Before going for a test ride, go back over all your work carefully. With the kit's fuse OUT and your bike's ignition turned ON, push the Horn Button. You should hear a soft click from the relay as it goes from OFF to ON. Install the fuse and test the horn(s). Be prepared for the shock blast.

Other Notes: Battery connectors do corrode over time. Special non-conductive grease is available to avoid this. If you find your battery terminals are covered with some kind of this grease, you must clean and remove all of this material before re-attaching any wires. Then re-apply it if desired, when you're finished. Make sure any battery terminal shields are not broken, and are properly replaced when finished. Battery connections that are not covered with grease should be removed and cleaned yearly, so don't avoid this important step. Don't over tighten connectors, and check the routing and condition of all existing bike wiring you see as you go. It is very important on a bike that wiring is not being rubbed or worn between other bike parts, or allowed to hang loosely with movement. The relays are light and tough enough to just hang on tie-wrapped wiring under the gas tank or you can tie wrap them to any convenient position in a fairing or relay box. Pay attention that no wiring is pulled or pinched when the handlebars are moved from the full left to full right positions.

As mentioned, check out the existing wiring very carefully as you install the kit. You never know what evil electrical connections have been made to your bike, even if it's always been dealer serviced.

Do not wire in another electrical device to a horn relay kit. Horns draw a lot of power; leave them on their own relay and circuits. If you want to wire in accessories, buy one of my Accessory Relay Kits for that purpose.

I guarantee the quality of my kit and its components. I guarantee that it is wired correctly and if you follow my instructions carefully you will have no problem. I can not be responsible for any other wiring on your bike. I also can't be responsible for connectors other than supplied on the kit, or problems caused by poor installation.

Jim Davis