Aux Lamp Wiring
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Tourer
Joined: Jul 2011
Posts: 444
Likes: 1
From: Grand Rapids, MI
Aux Lamp Wiring
Hi all: Working on my winter mod of adding LED Aux lamps to my Fatbot. I need to decide how to actually wire the lights up. The way harley wants it done is to splice off of the lower headlamp feed, run it to a toggle switch, and then to the lights. This will result in the aux lamps only operating while the low beam is on and is probably the legal way of doing it.
HOWEVER, I am not worried about the legality and was thinking of an alternate wiring. According to the service manual, there should be an aux wire just behind the headlight assembly. This Aux circuit has a 15-amp fuse. My plan is to splice off of it and run it directly to the Aux lamps without using the toggle switch (which I think looks real tacky). This way they would stay on at all times. Since I am going with LED lights, the current draw will be minimal. What do you think of this plan?
Also, I plan on drilling the back the the aux lamp bucket and installing a grommet through which I would run 1/8 inch stainless-steel braided wiring loom. I can then dress up the bottom of the light bar rather than have the threads showing. Does someone make SS braided looms that ALSO have a plastic liner?
Thanks for the input, Chris.
HOWEVER, I am not worried about the legality and was thinking of an alternate wiring. According to the service manual, there should be an aux wire just behind the headlight assembly. This Aux circuit has a 15-amp fuse. My plan is to splice off of it and run it directly to the Aux lamps without using the toggle switch (which I think looks real tacky). This way they would stay on at all times. Since I am going with LED lights, the current draw will be minimal. What do you think of this plan?
Also, I plan on drilling the back the the aux lamp bucket and installing a grommet through which I would run 1/8 inch stainless-steel braided wiring loom. I can then dress up the bottom of the light bar rather than have the threads showing. Does someone make SS braided looms that ALSO have a plastic liner?
Thanks for the input, Chris.
Grand HDF Member
Joined: May 2008
Posts: 4,624
Likes: 189
From: Newcastle, Ca.
Installed a relay with inline fuse from the battery to switch, to passing lamps. The relay is triggered by a passing lamp wire so when bike is turned on, relay supplies voltage to lamp switch.
Club Member
Joined: Sep 2010
Posts: 15,425
Likes: 7,120
From: Beyond Fucital
I think the AUX wire your talking about is prewired so it goes off when you hit the high beams. You ca put a 12volt dc relay in the bucket that will allow power to the AUX lights. wire the AUX lights to the common, low beam to the N/C, high beam to N/O and relay coil, , other side of relay coil to ground. You can get a small Ice cube relay at Radio Shack. Heat shrink all your splices. Everything you need is in the bucket.
Hell ride over I'll do it for you, no charge. You bring the parts and beer.
Hell ride over I'll do it for you, no charge. You bring the parts and beer.
Last edited by RANGER73; Jan 21, 2012 at 08:59 AM.
Thread Starter
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Tourer
Joined: Jul 2011
Posts: 444
Likes: 1
From: Grand Rapids, MI
I guess a little testing is in order. I have to say that I did not get the impression the aux circuit was tied to the lamps in any way. Multimeter and 10 minutes should tell the tale.
Road Captain
Joined: Sep 2010
Posts: 535
Likes: 0
From: Huntington Beach
HD designed the passing lamps to be tied into the low beam side of the hi-lo switch. There is a yellow wire w/connector that exits the headlight loom right near the headlight housing, which is the low beam circuit. That connector is designed for the passing lights mating connector.
I rewired mine to the blue wire that goes up to the left hand controls, which is the wire that feeds the hi-lo switch. I left the passing light toggle switch in series so that I could turn them off, although I always leave them on. Wiring it this way also relieves the burden of the passing lights from the hi-lo switch.
The headlight circuit is on a dedicated 15 amp fuse. The difference between low beam and high beam is about a half amp. I checked the current draw on mine with the passing lights on, Im pulling about 8 amps on low, 8.5 on high. With the passing lamps off I get about 4 amps on low and 4.5 on high. This is all within the designed capabilities of the lighting circuit and overload protection.
I rewired mine to the blue wire that goes up to the left hand controls, which is the wire that feeds the hi-lo switch. I left the passing light toggle switch in series so that I could turn them off, although I always leave them on. Wiring it this way also relieves the burden of the passing lights from the hi-lo switch.
The headlight circuit is on a dedicated 15 amp fuse. The difference between low beam and high beam is about a half amp. I checked the current draw on mine with the passing lights on, Im pulling about 8 amps on low, 8.5 on high. With the passing lamps off I get about 4 amps on low and 4.5 on high. This is all within the designed capabilities of the lighting circuit and overload protection.
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Stellar HDF Member
Joined: Feb 2010
Posts: 3,393
Likes: 260
From: Southern California
Used a Relay and two Diodes.
The Negative Terminal of the Relay Control Winding is grounded through the Driving Lamp Switch.
The Positive Terminal of the Relay is attached to the Cathodes of both Diodes.
The Anode of each Diode is attached: One to the Low Beam circuit and the other to the High Beam circuit.
The Driving Lamps are powered by the Relay via a dedicated Circuit that reduces the circuit Voltage Drop. Between the better wiring and the use of 886 50W Bulbs I get the most out of these lamps.
Doing it this way makes sure that:
1.) The Relay will be "On" with the Fog Lamp Switch turned "On" with either the High or the Low Beam and the High and Low beam Circuits are isolated from each other by the Diodes.
2.) It also ensures that the Relay will be "Off" if both Low and High Beam are "Off" (Ignition Switch "Off"). This prevents the battery from being run down because I forgot that the Driving Lamps were "on" when I walked away from the bike.
3.) I retain control of the Driving Lamps with the original switch.
4.) I have very nice lighting with either High or Low Beam and I can get replacement bulbs at any parts store.
The Negative Terminal of the Relay Control Winding is grounded through the Driving Lamp Switch.
The Positive Terminal of the Relay is attached to the Cathodes of both Diodes.
The Anode of each Diode is attached: One to the Low Beam circuit and the other to the High Beam circuit.
The Driving Lamps are powered by the Relay via a dedicated Circuit that reduces the circuit Voltage Drop. Between the better wiring and the use of 886 50W Bulbs I get the most out of these lamps.
Doing it this way makes sure that:
1.) The Relay will be "On" with the Fog Lamp Switch turned "On" with either the High or the Low Beam and the High and Low beam Circuits are isolated from each other by the Diodes.
2.) It also ensures that the Relay will be "Off" if both Low and High Beam are "Off" (Ignition Switch "Off"). This prevents the battery from being run down because I forgot that the Driving Lamps were "on" when I walked away from the bike.
3.) I retain control of the Driving Lamps with the original switch.
4.) I have very nice lighting with either High or Low Beam and I can get replacement bulbs at any parts store.
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Tourer
Joined: Jun 2007
Posts: 362
Likes: 3
From: South Orange County, SoCal
Mine were originally jumped off the low beam light as directed. I pulled mine off that yellow low beam power wire so I could have passing lamp power with high or low beams. The lamps are now rewired off the orange with white stripe auxiliary wire. It required removing the fuel tank to access that wire.
Thread Starter
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Tourer
Joined: Jul 2011
Posts: 444
Likes: 1
From: Grand Rapids, MI
Mine were originally jumped off the low beam light as directed. I pulled mine off that yellow low beam power wire so I could have passing lamp power with high or low beams. The lamps are now rewired off the orange with white stripe auxiliary wire. It required removing the fuel tank to access that wire.