Horn Lites for Bikes

So, I tried it with the high beam. It was easy to do with a standard relay (if you don't understand how or why we should use a relay, see Installing Extra Horns for a very basic explanation). But it was unsuccessful for three reasons. One: the filament of the high beam takes about a second to warm to full intensity, which caused the flicker of the light to NOT coincide with the beep of the horn. Two: With both the high beam and the low beam filament lit, the contrast when the high did reach intensity was minimal, and barely noticeable in daylight, with the short pulse of the horn. Three: Flashing headlights or auxiliary lamps in traffic may not be such a good idea after all. Why? Because, a common signal used in traffic to let another driver know that it is OK for him to proceed (i.e. "Go ahead, make your left turn in front of me, I will wait.") is the flashing of headlights on and off. Maybe not wise. You will certainly get the attention of the other driver, but that driver may just think that you are telling him to go right ahead and pull out in front of you. Precisely the OPPOSITE of what we were trying to accomplish.

In fact, with or without this mod in place, flashing your headlight to gain the attention of another driver is a poor idea. It may be mis-interpreted by other drivers as stated above. Every truck driver on the road knows what flashing headlights mean. "You go right ahead and pull in front of me." That particular question is even on our motorcycle permit written test here in Ohio, as my 17 year old daughter reminds me. If you mark it yes, you get it wrong. If you do wish to gain the attention of another driver with your headlight, switch its state only ONCE. That is, go from lo to hi or from hi to lo. Please don't repeatedly flicker your light to get attention in traffic.

I have tried blinking different lights with this mod, from the headlamp high beam, Cobra light bar, my auxiliary fog lamps to switching the lo beam off and lighting up the hi. They are all relatively easy to wire up using these parts. I settled on flashing only the turn signals. Instead of saying something to cagers that may be mis-interpreted, it says "hazard!" all around the bike. You can even "beep" the horn at someone behind you, a tailgater perhaps. I will describe only that wiring because of the reasons stated above. I do not recommend that you blink any other lights with this mod. Even just blinking the turn signals may be illegal in your state, so I don't even recommend that you do this either, unless you want to impress folks at shows or ride in parades and blink your lights and beep your horn with only one button. When you ride in traffic on highways, switch them off, please.

QUICKLY FOR THE EXPERT: Supply a key on +12V through the relay to both signal circuits when triggered, while keeping them ISOLATED when not triggered which requires a DPDT relay (see FOUR WAYS for FIVE BUCKS! for the reason why). Activate the relay with the +12V horn wire.
NOTE: this can be accomplished without a relay by using a pair of 3 AMP diodes/rectifiers (RS 276-1144) to power the two signal circuits with the single horn hot wire. This has two drawbacks: 1) It may overload the horn circuit and burn the switch (if you already use a relay to blow the horn, use diodes to run the signals, it's easier. Run them off the power out 87 terminal) (see below) 2) the diodes tend to heat up when powered for long periods. For a drawing of how to do this if you use a relay for your horn, check our Horn Relay page and see the drawing below.

QUICKLY FOR MOTORHEADS: See the drawing. The horn wire triggers the relay which then feeds current to the signal lamps. The lamp circuits revert to isolated when the relay is "off".
NOTE: this is a "layman's" drawing which shows only the terminals on the various parts. It is intentional that there are no electronic symbols included.

FOR THE REST OF US: Prepare for installation by pre-soldering your relay with five inch pigtails. Solder five inches of wire (18-20 gauge) one each to the four terminals at each corner of the relay. In the drawing these are both COIL terminals and both N.O. [Normally Open] terminals. Clip and insulate the N.C. [Normally Closed] terminals, since they are not used. Solder a heavier lead (16-18 gauge wire) to BOTH the COM terminals, bridging them together. Wrap the relay in such a way that these terminals will not come in contact with anything else or each other. NOTE: when soldering, use the forceps to clamp the wires to the base of the narrow terminals and solder at the top end. The forceps serve as a heat sink to keep you from damaging the relay. This may or may not be necessary, but it is good practice when heating miniature electronic components.

In the following, wires and parts referred to by color etc. will vary according to the bike onto which you are installing. Here, we will describe the method to install this onto a Honda Valkyrie for color match wires and other parts.

Disconnect the negative battery terminal as a precaution at this time. Remove your headlight rim by removing the phillips screws located at 4 o'clock and 8 o'clock on the rim. Placing your hand on the top of the rim to hold it in place, pull outward on the bottom of the rim to release. Holding the rim, unplug the headlamp and set the rim aside. Loosen the clips that hold the harnesses in place.

Get +12v from the horn hot wire
On the right side as you face the open Valkyrie nacelle, find the large RED connector (located about 2 o'clock). There are nine wires in that plug. Locate the LIGHT CELERY GREEN wire which is in one of the corners of the plug. That is your horn wire, the one that goes "hot" when you beep the horn. You will likely have to peel back some of the loom tape to get enough wire to hook into. With a connector, hook into this wire with either of the coil pigtails (one coming from the lonely terminals on the end of the relay).

Using a switch
A switch is NOT optional. There are times when you don't want to have your lights blinking with the horn. It may be interpreted as "impersonating an emergency vehicle" in some states which is illegal. You may need to pass inspection and this would cause to you fail. I suggest that you mount your switch to break the ground, which is the wire we hook up in this step. This minimizes shorting risk, and prolongs the life of the switch. Figure out where you want to mount the switch, run enough wire to reach it, and put the switch between this next pigtail and the connection described.

Hook to ground through the switch
Locate any DARK LIME GREEN wire (there are several) inside the headlight. Hook the other lonely coil terminal to that wire, which is ground, through your switch.

Tie into the signal circuits
Hook the other END terminals of the relay to your signal circuits, one each side. On the Valkyrie, locate the SOLID ORANGE wire, which is connected with a bullet connector, and hook one of the other END terminal pigtails to that. Locate the SOLID LIGHT BLUE wire, which is connected with a bullet connector, and hook the other END terminal pigtail to that. Make sure you hook to the SOLID color wires and not the wires with white strips down them. Keep these isolated from each other.

Supply current to the signals
Now you need to hook the remaining pigtail (the one that bridges both terminals) to a wire that is +12v hot with the key on. For the Valkyrie, find a SOLID BROWN wire. There are several in there to choose from.

Perform the smoke test
Everything OK? Lights light up with the horn? Believe it or not, you're NOT done! Not yet, anyway. Test your turn signals. If they no longer work properly, you've used the wrong relay or you've crossed the wires that we needed to keep isolated. If it all works ok, both your signals and new horny lights, then button her up. Impress your friends in your driveway Then switch them off and go for a ride.

HORNY AUX LAMPS

I'm still no fan of blinking the headlight with the horn, but after considerable mileage with this circuit which is more noticeable than "Horny Lights" I'm a believer in blinking your AUX Lamps with the horn. They can be fog lamps, light bars or any up front aux lamps that you already work with a relay (NOT YOUR HEADLIGHTS!).

This little circuit knows if your aux lights are on and will blink them off when the horn beeps. This little circuit knows if your aux lights are off and will blink them on when the horn beeps.

About $5 total..... you can use a standard 5 pin Bosch style relay or what I used, a Radio Shack micro 12v relay for a computer (275-241 which is only about half an inch square). Diodes can be little 1 amp jobs (RS 276-1102) since you're only pushing relay triggers.

[Click for the 275-241 relay.] -- [click for the diodes]

CAUTION: THIS MOD MAY BE ILLEGAL IN YOUR STATE^†. CHECK WITH YOUR STATE LAW ENFORCEMENT AGENCY BEFORE PERFORMING THIS MOD. USE AT YOUR OWN RISK.

^† In keen awareness of the international forum into which this article is published, the word "state" is used in lieu of province, country, principality, canton, territory etc. Substitute any word which may apply in your case.
^‡ This mod can be performed on any modern motorcycle which employs the same circuitry: a wire that goes hot when the horn is beeped and isolated left and right signals.

More how-to articles for the Valkyrie
Feet Heaters	Rear Marker Lights	Four Way Flashers	Carb shims
Signal Buzzer	Driving Lights	Horny Lights	Invisible Vista
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