Comagination dual headlight modulator kit
(left); modulator kit with solid-state relay
(includes wiring to battery), right.
Dual Headlight Modulator
Assistance provided by Bill C.
See Below: Unique new
Comagination dual headlight modulator
includes a solid-state relay!
Give me some metal and a few
tools and I'll build anything. But when it comes
to electricity, I'm dumbstruck.
I'm not sure why actually, although I
stuck my finger into way too many outlets as a toddler,
so perhaps it's a Pavlovian reaction to all things
I wanted to install a headlight
modulator in our latest test mule, our '98 Triumph
Tiger, but the Tiger's twin headlights (which are both
on when the bike is running) caused me some concern. I had visions
of having to rip apart the entire wiring harness, sparks
flying, trying to get both headlights synchronized with
a pair of modulators.
We've installed several modulators over
the years (see the
U.S. Federal regulations allowing headlight
modulators on motorcycles and the
Canadian regulations covering the same), and the
combination of a headlight modulator, a brake light
flasher and extra LED brake lights is a standard safety
package installed on all webBikeWorld machines.
Are Modulators Legal?
By the way, there is still some
misinformation around the Internet regarding headlight
modulators. You've probably read a thread in a
motorcycle discussion group where the author will state
that modulators are not good, they're illegal, they
"blink on and off" and send the wrong message to
oncoming drivers, etc. It's usually immediately
apparent that they were written by someone who has
never seen a modulator in use.
Although there are no studies that we
are aware of that prove the effectiveness of modulators
for motorcycle visibility, both the U.S. and Canadian
governments have approved them for use in all 50 states
and all Canadian provinces. Motorcycle headlight
modulators do not "blink the lights on and off".
We took a
short (10 second or so) Quicktime video clip of the
Comagination modulator in action on the Triumph Tiger to
give you an idea of what a motorcycle headlight
modulator looks like in use. Note that
Quicktime is available as a
free download on the Apple website.
Comagination Headlight Modulators
Our experience with the Comagination
Visipath single bulb headlight modulator has been very positive (see
review and installation article), so I visited their
website to see if they had any tips on installing a
headlight modulator on a twin headlight motorcycle like
That's where I found Comagination's dual
headlight modulator, available with or without a
built-in solid-state relay. The 1995 and later
Tigers already have headlight relays installed at the
factory, according to my Triumph wiring diagram, but we
tried both Comagination modulator kits for evaluation
The modulator with solid-state relay kit
is a new and unique device; Comagination says that it's
the first application of its kind. A solid-state
relay has several benefits, including low cost, small
size, fast switching and no moving parts. The
modulator with solid-state relay (Model AIODR20H4) has a
list price of $109.90 (plus S&H), is rated to work with
bulbs up to 115 Watts and can be used to modulate either
the high beam or low beam.
The non-relay version of the
Comagination headlight modulator (Model D115H4) has a
list price of $79.95 (plus S&H) and is rated to work
with bulbs up to 115 Watts. 115 Watts is probably
way more than any motorcycle headlight reflector or
housing can handle without melting, but it's nice to
know that it has this capability.
Installation of the dual headlight
version couldn't be easier. Both kits come with a
one-page instruction sheet, and the folks at
Comagination are available for help if needed. The
steps are identical to the single headlight version
installation, except there are two pairs of connectors,
one for each headlight.
Photo 1: Non-relay version
of headlight modulator. Note two pairs of
male and female three-pronged connectors.
The light sensor is not visible in this
Photo 2: The
modulator's electronics are all contained in
Photo 3: Modulator
light sensor located on the rear view
mirror. The lower cable tie secures
the sensor while the upper cable tie is just
tight enough to hold the sensor in place
without undue pressure.
Photo 4: A small
screwdriver is necessary to remove the male
blades and the female receptors to switch
wires for low beam modulation.
The back of an H4 headlight bulb has
three prongs attached, which are used to power the bulb
(low, high and ground). Unplug the female
connector from the back of the bulb and plug in one of
the modulator's female three-pronged connectors in its
At the opposite end of the wires that
lead from the female bulb connector is a male connector
that plugs into the bike's electrical system.
Unplug the male three-pronged connector
and plug in the matching connector from the modulator
and you're just about done.
The male/female connectors on the
Comagination kit are paired (Photo 1); the modulator
(blue cylinder, Photo 2) is located in the middle of the
two pairs of connectors.
I'll just about guarantee that it will
take longer to access the back of your bike's headlight
than it will to connect the modulator kit. The
Tiger's headlight bulbs are easily accessible by simply
reaching up behind the fairing, and installing the
connectors took only a couple of minutes.
The only thing left to do is to find a
location for the modulator's light sensor. U.S.
and Canadian laws regulating motorcycle headlight
modulators require that the modulation ceases below
certain light levels.
So every modulator kit comes with an
"electric eye", that is, a tiny sensor that senses the
amount of background light and stops the modulator when
The sensor must be located upright and
in a location where it won't be affected by shadows from
a fairing or other accessory. The thin wire from
the sensor is fed back through the headlight or fairing
and the sensor can be located in a convenient position.
Since the Tiger has a small fairing and
the headlights are not housed in headlight shells, it
was very easy to run the wire out the back of the
fairing. I located the sensor on the right hand
rear view mirror (see Photo 3), and it works well.
High or Low Beam Modulation?
Comagination recommends modulating the
headlight's high beam, and their modulators are set to
do so at the factory.
We've used motorcycle headlight
modulators for many years, and our feeling is that high
beams distract other drivers to a point of annoyance,
and the high beam can also interfere with an oncoming
driver's ability to see the motorcycle's directionals
However, modulating the high beam can
provide a greater area of visible modulated light,
because of the wider projection of high beams.
Also, the headlights can be switched to low beam to turn
the modulator off.
It's a matter of personal preference,
but we prefer to modulate the low beam.
One of the nice features of the Comagination modulators
is that they can be converted from modulating the high
beam to modulating the low beam by switching the wires.
The process is described in the installation
instructions, and it's a simple matter of swapping the
red and blue wires in both the male and female
connectors on the modulator.
The wires are removed from the plugs by
sliding a small screwdriver blade into the little
rectangular hole next to the male or female connectors
It takes a bit of fiddling (the male connectors come
apart much easier than the female connectors), but it's
relatively easy to do. We swapped our wires to
modulate the low beam.
Follow the instructions, although note
that although Comagination provides the information on
how to modulate the low beam, they say "We only
recommend and support high beam modulation." I'm
not sure what it means to "support high beam
modulation", but there you have it.
We also recommend using some electrical
tape to hold the connectors together and using the
supplied cable ties to make sure the modulator's wiring
harness is secured to the bike. When mounting the
sensor on the handlebars, like it is on our Tiger, make
sure there's enough play for the handlebars to turn back
and forth without binding.
Photo 5: Relay version
of headlight modulator. Note two pairs
of male and female three-pronged connectors.
The light sensor is not visible in this
Unique New Type of Headlight Modulator With Solid-State Relay
The Comagination modulator is also available with a
unique solid-state relay (Model AIODR20H4).
Comagination says that this is the "world's first"
modulator using this technology, and webBikeWorld is
honored to have been offered the first opportunity to
try this device.
The relay must be very small,
because there's no difference in size between
the blue cylinder that holds the electronics in the
standard modulator and the relay version.
A Note About Relays
Relays are powered switching devices
that are sometimes used on motorcycles to switch
accessories that are under heavy electrical loads at
startup, such as the headlights or horn(s).
Motorcyclists may find that adding a headlight relay
and a wiring harness which brings power directly from
the battery to the headlights will increase the
brightness of the bulb, because wiring harness losses
We have noticed a difference in brightness after
installing a headlight relay to a
late-model motorcycle that had a very narrow gauge wire powering
the headlights. The robust wiring of the relay's harness
helped bring full power to the headlights, lending them
a greater apparent brightness. We're not sure if
it was the result of the wiring, the relay or both, but
Another benefit of adding a relay to the
headlights is that the motorcycle's switchgear may last
longer. Using a relay eliminates the heavy
electrical load that runs through the handlebar
switchgear, which can cause arcing and heating
degradation of the switch component.
Adding a headlight relay, especially for
a motorcycle with dual headlights, can be much more
complicated than adding a simple modulator. Also,
relays are relatively large, and finding a secure
location to mount one or two adds to the difficulties.
And most relays used in motorcycles are
electro-mechanical devices with internal moving parts,
subject to breakage.
Comagination Headlight Modulator With
Comagination has developed a unique and
interesting "breakthrough" design by adding what they
say is the world's first solid-state relay to
their headlight modulator. The relay modulator kit
(Photo 5) is similar in appearance and construction to
the standard dual headlight unit described above (Photo
1), with a
few minor exceptions.
Both female headlight bulb connectors
are replaced with this modulator's connectors, just like
the standard (non relay) modulator described above. However, only one male headlight plug is
used to connect to one of the headlight power supply
connectors. The motorcycle's second connector is
not used, and must be disconnected from the second
headlight and secured with electrical tape.
The single connection will power the
relay, which will then signal the relay to turn on the
headlight high or low beams, while the modulator will
modulate the headlights (or headlight in the single
headlight version). The other major difference is that the
modulator with relay kit includes a separate wiring
harness for accessing electric power directly from the
It's important to follow the
instructions provided with the unit, but in general, the
wiring harness plugs in to a male and female connector
that extend from the relay (blue cylinder) and the other
end of the harness is routed through the bike and back
to the battery, where it is connected to the positive
and negative terminals. Several cable ties are
provided to secure the harness. A 20-Amp plug-in
fuse and fuse holder is also provided.
The modulator with relay kit is only
slightly more difficult to install than the non-relay
kit; there's less work up front near the headlights, and
slightly more work in routing the extra harness back to
the bike's battery. But everything is well marked
and the connectors are high quality, so it's not really
very hard to install. Much easier, in our opinion,
than installing a separate headlight relay harness.
Also, the modulator kit with relay can
also be switched from high to low beam modulation by
swapping the blue and red wires using the same technique
The Comagination headlight modulator with relay is a
unique "breakthrough" product, and it eliminates the
complications with installing a separate headlight relay
switching system. Its solid-state relay lowers the
cost and effort of adding a headlight modulator and
relay because the two products are combined into a
single unit. The modulator is very small; it's
smaller than other modulators, and much smaller than a
separate modulator and relay system. The
solid-state construction also means faster switching
speeds and no mechanical relays to fail.
Both versions of Comagination dual headlight modulator kits
easy to install and have no moving parts. The
claimed to be the "world's smallest", and most motorcycle headlight shells should
have enough room to install the unit. Note that
although we installed the dual headlight kit, a single
headlight modulator and modulator with relay is also
Motorcyclists with limited mechanical or
electrical skills should have no problem installing
these products, and we were
pleased to find that it's just as easy to install the
dual headlight modulator as the single headlight
We've been very satisfied with
Comagination's products and have no problems to report.
Our Comagination single headlight modulator has been in
use on two different motorcycles for about 3 years with
no problems. The prices are reasonable and the
products work as advertised.
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