headlight wiring
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From: California
headlight wiring
The stock headlight is an H4. There are 2 filaments. H4 has 3 wires: low beam, high beam, ground.
When the high beam switch is activated, is there still power going to the low beam filament? With the high beam switch turned on, is the bike supplying power to both low beam wire and high beam wire? Or is the low beam wire deactivated and power only flows through the high beam wire?
When the high beam switch is activated, is there still power going to the low beam filament? With the high beam switch turned on, is the bike supplying power to both low beam wire and high beam wire? Or is the low beam wire deactivated and power only flows through the high beam wire?
Stellar HDF Member
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From: Dallas, Texas
Do an experiment with a friend. Have the friend turn on the low beam light while you look directly for 30 seconds at it at less the 1 foot away. Then tell the friend to switch on the hi beam for 30 seconds. Now tell the friend to turn off the lights. NOW you can see how they work.
Seasoned HDF Member
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From: England
What year is your bike?
I think upto 2013 the switch on the handlebars was a change-over switch such that either high beam or low beam but not both.
You can see in wiring diagram blue is power to switch and then white or yellow will have power to the bulb. - 99949-13_en - 2013 Wiring Diagrams | Harley-Davidson SIP
Not sure what CAN bikes do.
I think upto 2013 the switch on the handlebars was a change-over switch such that either high beam or low beam but not both.
You can see in wiring diagram blue is power to switch and then white or yellow will have power to the bulb. - 99949-13_en - 2013 Wiring Diagrams | Harley-Davidson SIP
Not sure what CAN bikes do.
Club Member
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From: Beyond Fucital
The low beam turns off when the high beam is on.
If you have running lights, they usually turn off when the low beams turn off. This can be changed on Canbus systems
Or by adding a relay.
If you have running lights, they usually turn off when the low beams turn off. This can be changed on Canbus systems
Or by adding a relay.
Road Warrior
Joined: May 2017
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From: Scottish Highlands.
Thanks for that, I had a pair of additional day running strip lights mounted on the fork sliders of my 2011 Iron 883, those lights were wired up to the dipped beam light circuit (yellow wire). When I flipped the high beam the strip lights went out, so that confirms what you said that both beams are on separate circuits.
The strip lights were cheap Chinese units at Ł5 for the pair, they worked well until it rained as I found out that they weren't waterproof so I junked them and I bought a pair of resin encapsulated lights. I haven't wired the new lights to the harness yet, when I do I'll add a light relay to the headlight circuit so that when the high beam is selected the running strip lights will stay on. The wiring goes inside the fork gaiters and up to the main wiring harness behind the left plastic wiring caddy.
The photo below is of the old lights that weren't waterproof, they were nice and bright though.
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the switch on the handlebars was a change-over switch such that either high beam or low beam but not both
Would the front turn signal work the same way? Running lamp filament turns off as signal filament turns on?
Seasoned HDF Member
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From: England
The running lamp filament is about 5W. They stay on all the time.
Blue wire in connector 30 wired directly to light fuse. See wiring diagram above.
From 2014 there is a running light power output from the BCM. That will be programmable but I cannot say how it is set up.
Blue wire in connector 30 wired directly to light fuse. See wiring diagram above.
From 2014 there is a running light power output from the BCM. That will be programmable but I cannot say how it is set up.
Last edited by Andy from Sandy; Oct 17, 2021 at 02:38 AM.
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