Headlight & Stop/Start switch Relay install Question

[Gary1945]

How is a relay installed to keep the 5 amps that goes through your start/stop switch to prevent burning out the stop/start switch. Im told when you start the bike that the headlight goes out till it starts and this has something to do with it?? At any rate anyone have a wireing diagram of this modification? thanks.

[Chicago-Spike]

On the "How To" board in the 1800 Electrical thread, read posts 7 and 8 for the relay install and why it is needed;
http://www.vtxoa.com/forums/showthread.php?t=205934

[Dray]

The 5 amp draw thru the headlite will kill the contacts sooner or later.
Installing a relay will reduce that draw to only what is required to
activate the coil on the relay (low amp draw). It's a simple install that is well worth the time and effort. Highly recommended. Some install an off/on switch inline from the starter switch to the headlite relay coil so that they can have the bike turned on without having the headlite on when doing maintenance.

Dray

[Coyote7864]

Big Bike Parts makes a switch assembly that mounts on the top of
the clutch master cylinder.

If you route the darkblue/white stripe wire from the start/stop
switch to the BB switch assembly, and route the output of
one of the three switches to the headlight relay terminal 86
you can use the switch to turn off your headlight while doing
engine maintenance.

You can route one of the other switches to terminal 86 of the
lightbar relay and use it to turn your lightbar on and off.

Here is the recommended wiring for the two relays:


Terminal 30/51 on both relays: 12 gauge red wire coming from
battery positive thru in-line fuses.
Headlight fuse should be 7.5 amp,
lightbar fuse should be 7.5 amp for two 35 watt lamps or
10 amp for two 55 watt lamps.

Terminal 87 of headlight fuse to darkblue/white wire input to
the headlight high/low selector switch.

Terminal 87 of lightbar relay to lightbar lamps

Terminal 85 of both relays to ground.
You can use any solid green wire on the bike for ground,
or the battery negative terminal, or the unpainted chassis
of the bike.

Terminal 86 of headlight relay from switch that you selected as
headlight on/off switch

Terminal 86 of lightbar relay from switch that you selected as
lightbar on/off switch.

If you are required to automatically turn off the lightbar
when your high beam is activated instead of installing the
BB switch assembly in series with the darkblue/white stripe
wire that would normally connect the output of the
start/stop switch assembly to the left handlebar switch assembly,
connect the BB switch assembly in series to the white
wire output from the high/low selector switch.
This will allow you to conform to the NHTSA regualtions,
but you will only be able to switch your lowbeam off
for maintenance purposes, and you will require a third
relay if you want to have your high beam on a relay.

[Gary1945]

You all are the Bomb! thanks much.

[Gary1945]

One other thought I have,,why in the hell didn't Honda fix this knowing it will cook the start/stop switch.There seems to be no end to the fixes that are needed.

[369]

Stock C headlight with basic 20 amp, single pole, 2 terminal toggle switch inside, no relay, works great.
Heavy red/black wire from hdlt fuse and smaller red/black wire from start switch on 1 terminal, blue/white wire from hi/low beam switch on the other, no automatic hdlt, fine with me, manual control and saves start switch.

[dbx]

Stock C headlight with basic 20 amp, single pole, 2 terminal toggle switch inside, no relay, works great.

I just did the same thing, and now my headlight is brighter than before, with same old original bulb.
Must be getting more current by not going to the start switch and back through those chincy 22awg wires.
I was going to put a relay in, with a switch, then figured since I only have the single 55/60 watt light, a toggle on the headlight housing is all I need, compact w/black lever blends right in.
It's easily reached just under the top triple tree, out of sight, you'd never know it was there.

[Coyote7864]

The reach over the handlebars to the headlight housing is
too long for most of us. For safety reasons, it it best to
have the switches within a thumbs reach of the hand grips.

It is for that reason that most of us install a relay.
The relay allows a switch capable of handling only
a small current to control a larger amount of current
thru the main relay contacts.
You can hide the relay anywhere out of sight,
but I usually recommend the "secret" toolbox door
under the left painted sidecover as it is convenient
to the battery positive terminal.

The headlight shell appears to be plenty big, but there
are an awful lot of wires and large multipin connectors
already hidden inside it, and finding a good spot for
a large toggle switch can be tricky.

Then there is the resale value of the bike to consider.
The stock handlebar switches look a lot neater than
a toggle switch mounted on top of the headlight shell.

But to each his own.

I have even tried to help other forum members to install
Harley Davidson switch assemblies and custom
switch assemblies (like Jokers) made for Harleys on our
bikes. The main reason to go with Harley switch asemblies
is if the owner is already familiar with the Harley layout,
but they are also very convenient if you want to install
apehangers on your bike because the Harley switch assemblies
come with wiring about three feet long, much longer than
the stock VTX handlebar switch assemblies.

The Custom switch assemblies look almost like there
are no switches present at all. Really clean!

[mrmustang69]

I helped Gary1945 do this to his bike this weekend, but is there a way to actully test to see if this is workking after you rewire everything ...everything worked after we get it back together WHEW. but how can i test to see if the draw has been decreased? thanks Dana

[Coyote7864]

If you went to your local community college to get your associates degree
in electrical construction and maintenance or electronics design and
repair, then you would know about Ammeters which require you to break
the circuit apart and put the Ammeter into the circuit in series with the
load (headlight or lightbar). There are also clamp-on Ammeters which
do not require you to break the circuit apart, but do require you to
isolate the wire that you want to measure a distance away from
all the other wires that would normally be near it in the wiring harness or
in the headlight shell or under the painted sidecovers.

Clamp on Ammeters
have a large clamp that you put the wire thru and measures the amount
of current thru the wire by the strength of the magnetic field generated
by the current moving thru the wire. You would want to have the
headlight or lightbar switched on so that there would be
measurablle current thru the wire when you read the Ammeter.

Did you get the master cylinder mounted switch unit that I recommended?

The current into that switch assembly on the red wire should measure
about one half to one amp depending on whether you are powering only
a single headlight relay, or two relays, one for the headlight and
one for the lightbar. Some relays only require one quarter amp of current
to activate the coil, others a half amp. I did not specify any particular
relay so I cannot be sure of the specs on the relay that you chose to use.

The three output wires from that switch assembly are
yellow for the left switch
black for the center switch
blue for the right switch

Each of those wires that was connected to the coil
of a relay would measure a fraction of one amp, if you had the
Ammeter to measure them.

The most common way for a relay to fail, is for the coil to burn out.
In that case, the light that you want to switch on or off will not
light up, and you will need to replace the relay.

The other way that some relays will fail is that the switching contacts
will get welded together, and you will not be able to turn off the light.
If you installed an inline fuse holder between relay terminal 30/51
and the positive battery terminal, you can remove the fuse to turn out the light and prevent the battery from being drawn down
by the light when the engine is turned off.