Headlight popping fuses
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Joined: Nov 2018
Posts: 72
Likes: 11
From: OHIO
A 15 Amp fuse would be normal for that bike. The wiring is designed to handle that current. He should not replace it with a lower rated fuse. Instead, he will need to find the short & repair it. Checking the wiring with the daymaker light disconnected is a good place to start troubleshooting. It's doubtful the light itself is shorted, but if the fuse doesn't blow with the light disconnected, it will be suspect & probably should be replaced or very carefully tested.
Road Captain
Joined: Aug 2008
Posts: 635
Likes: 388
From: Philadelphia Northeast
If it pops only on high beam there is not much wiring to check. It's a white wire that feeds the hi beam lamp and high beam indicator under the speedo from the switch. So trace the harness all the way from headlight to indicator lights and to the left handlebar switch. Pay attention to the spots where it possibly touches the metal. If your handlebar is internally wired look first where the harness goes into and out the handlebar. Open up the switch housing and check for wire rubbing inside.
Road Master
Joined: Dec 2016
Posts: 1,051
Likes: 399
From: Bournemouth United Kingdom
Power (watts) = voltage X current and Voltage = current (amps) X resistance (ohms)
Using the above formulas you could work out exactly the current draw with the wattage of the Daymaker or the resistive value of the circuit. Important bit: It is good practice to have the correct fuse rating fitted to any circuit irrespective of wire gauge used.
If the good suggestion from PlasmaNaut does not yield anything obvious next stage is to take any bulbs out in the remaining circuit to prevent earth/ground paths get a multimeter or someone to assist that knows how to wield one and the fault could be traced in no more than a few minutes. Good luck.
Last edited by K9F; Aug 28, 2020 at 09:08 PM.
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Joined: Nov 2018
Posts: 72
Likes: 11
From: OHIO
don't think that it is the head light I removed the light and it still tripped the fuse
Grand HDF Member
Joined: Sep 2013
Posts: 3,820
Likes: 588
From: Michigan
I agree the 15 amp would be normal for that bike with a standard incandescent headlight but the circuit now has greatly reduced current draw due to the LED Daymaker having been fitted. It is the circuit consumers that dictate fuse rating not the wiring.
Power (watts) = voltage X current and Voltage = current (amps) X resistance (ohms)
Using the above formulas you could work out exactly the current draw with the wattage of the Daymaker or the resistive value of the circuit. Important bit: It is good practice to have the correct fuse rating fitted to any circuit irrespective of wire gauge used.
If the good suggestion from PlasmaNaut does not yield anything obvious next stage is to take any bulbs out in the remaining circuit to prevent earth/ground paths get a multimeter or someone to assist that knows how to wield one and the fault could be traced in no more than a few minutes. Good luck.
Power (watts) = voltage X current and Voltage = current (amps) X resistance (ohms)
Using the above formulas you could work out exactly the current draw with the wattage of the Daymaker or the resistive value of the circuit. Important bit: It is good practice to have the correct fuse rating fitted to any circuit irrespective of wire gauge used.
If the good suggestion from PlasmaNaut does not yield anything obvious next stage is to take any bulbs out in the remaining circuit to prevent earth/ground paths get a multimeter or someone to assist that knows how to wield one and the fault could be traced in no more than a few minutes. Good luck.
That is NOT true. The circuit wiring gauge is a critical part of the circuit design & MUST be considered for both circuit design & circuit protection.
Again, there is no reason to change to a smaller fuse simply because he switched to an LED. Whether the LED uses 2 amps or 10 amps, the overall circuit design & capacity is designed for 15 amp fused protection. The LED light poses no issue being installed in that circuit using the correct (15 amp) fuse. Should the light short, the fuse will blow as designed. If the light fails open, the fuse would not blow, even if it were replaced with a 1 amp fuse.
Last edited by Hammz; Aug 29, 2020 at 12:20 AM.
Cruiser
Joined: Aug 2019
Posts: 106
Likes: 67
From: Indianapolis, IN
I am by no means a tech so I might be out on a bit of a limb...
I agree with others that there may be a short, but could it possibly the hi low switch itself on the grip.
I only mention from the point of home ownership/maintenance experience. Fuse in fuse box would keep flipping because wall switch was bad, not necessarily the lamp or the bulb utilized within.
Again, not a tech, just mentioning.
Hope a solution presents itself soon!
Ride safe.
JS2
I agree with others that there may be a short, but could it possibly the hi low switch itself on the grip.
I only mention from the point of home ownership/maintenance experience. Fuse in fuse box would keep flipping because wall switch was bad, not necessarily the lamp or the bulb utilized within.
Again, not a tech, just mentioning.
Hope a solution presents itself soon!
Ride safe.
JS2
Road Master
Joined: Dec 2016
Posts: 1,051
Likes: 399
From: Bournemouth United Kingdom
I will not get into a ***** waving or peeing competition with anyone over this by splitting hairs. We are talking about a motorcycle circuit with probably 16 to 22 gauge wiring in your money at most. With over 40 years experience as an electrical engineer It amazes me how threads can quickly digress by people heading off on a tangent by those that obviously think they have superior knowledge. Apologies Longpockets. Feel free to continue to contact me by PM should you need any further assistance. Good luck once again.
Knock yourself out. Current carrying capacity of cables by gauge and length. You could potentially stick a 25 amp fuse in if the cable length is under 3 feet in length and 16awg. Not advisable though.
https://www.wiringproducts.com/automotive-wire
Knock yourself out. Current carrying capacity of cables by gauge and length. You could potentially stick a 25 amp fuse in if the cable length is under 3 feet in length and 16awg. Not advisable though.
https://www.wiringproducts.com/automotive-wire
Last edited by K9F; Aug 29, 2020 at 03:29 AM.
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Tourer
Joined: Dec 2008
Posts: 272
Likes: 74
From: Stowe Pa
I will not get into a ***** waving or peeing competition with anyone over this by splitting hairs. We are talking about a motorcycle circuit with probably 16 to 22 gauge wiring in your money at most. With over 40 years experience as an electrical engineer It amazes me how threads can quickly digress by people heading off on a tangent by those that obviously think they have superior knowledge. Apologies Longpockets. Feel free to continue to contact me by PM should you need any further assistance. Good luck once again.
Knock yourself out. Current carrying capacity of cables by gauge and length. You could potentially stick a 25 amp fuse in if the cable length is under 3 feet in length and 16awg. Not advisable though.
https://www.wiringproducts.com/automotive-wire
Knock yourself out. Current carrying capacity of cables by gauge and length. You could potentially stick a 25 amp fuse in if the cable length is under 3 feet in length and 16awg. Not advisable though.
https://www.wiringproducts.com/automotive-wire
Seasoned HDF Member
Joined: May 2008
Posts: 21,176
Likes: 12,753
From: South Carolina
The fuse is there to protect the wiring.
The component(s) dictate how much amperage the circuit must carry.
The wire is sized according to the maximum amperage the circuit may carry.
The fuse is sized to protect the wiring.
Last edited by Dan89FLSTC; Aug 30, 2020 at 07:40 PM.