Rear lights keep burning out... Please help
Thread Starter
|
Road Warrior
Joined: Feb 2014
Posts: 1,851
Likes: 420
From: Santa Fe NM
Rear lights keep burning out... Please help
Rear light bulbs keep burning out immediately after replacing the bulbs. I checked the wiring and all seems to be in good condition. I don't see any worn or exposed wires that could be grounding out or anything like that. Does anyone have any ideas on what could cause this or suggestions for diagnosing the problem? Thanks.
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
It is probably a damaged or loose wire, or poor ground, despite your efforts checking. Having done a visual check the next step is to use a multimeter to check electrical continuity along each part of the circuit. Trace the wiring for the rear lights back under the saddle and disconnect it, then check each wire in turn. There will be a sneaky fault lurking in there somewhere!
Thread Starter
|
Road Warrior
Joined: Feb 2014
Posts: 1,851
Likes: 420
From: Santa Fe NM
It is probably a damaged or loose wire, or poor ground, despite your efforts checking. Having done a visual check the next step is to use a multimeter to check electrical continuity along each part of the circuit. Trace the wiring for the rear lights back under the saddle and disconnect it, then check each wire in turn. There will be a sneaky fault lurking in there somewhere!
Thanks for the suggestion. I have located the wires and connectors. I have never worked on electrical components so any specific details on what I'm gonna be doing and looking for will be very helpful.
So with the multimeter do I need to probe each wire while grounding the common probe and check for voltage? How exactly will I know if there is a fault? Also should I do this to both sides of the connectors? One last question is should I keep the power on and hooked up or disconnect the battery or main fuse while doing this?
Sorry if the questions are dumb to some here but I need to learn this stuff so I can fully work on my bike myself instead of paying way too much for someone else to do it for me. Please help! I need to get this figured out.
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
Let me start by saying that many electrical problems, probably including yours, are mechanical! That is to say that the electrical function of your light is interrupted by a mechanical problem, such as a damaged or broken wire, bad ground (often caused by rust). The challenge ahead is to identify and fix that mechanical problem, after which the electrickery can flow once more. A common cause is if you have lowered shocks, as the wiring under the rear fender can be damaged by the tyre.
The basic way of tracking the problem is by 'continuity testing'. This essentially involves checking each wire to confirm if it is providing a continuous mechanical/electrical circuit. It can be done by checking the resistance of each wire, or the presence of battery voltage. There are stacks of entries and videos on the internet about doing that testing and instead of me writing yet another, I recommend you search for something that you like the look of. Best to use car or bike 12 volt tutorials, rather than domestic mains ones (although the principle is the same).
If you have a pal who can give you a helping hand, over a beer or two, you'll find that two heads are better than one!
The basic way of tracking the problem is by 'continuity testing'. This essentially involves checking each wire to confirm if it is providing a continuous mechanical/electrical circuit. It can be done by checking the resistance of each wire, or the presence of battery voltage. There are stacks of entries and videos on the internet about doing that testing and instead of me writing yet another, I recommend you search for something that you like the look of. Best to use car or bike 12 volt tutorials, rather than domestic mains ones (although the principle is the same).
If you have a pal who can give you a helping hand, over a beer or two, you'll find that two heads are better than one!
Seasoned HDF Member
Joined: Aug 2014
Posts: 35,239
Likes: 19,070
From: 40.2444° N, 75.6419° W
I can tell you that when tis happens in a car, it is a voltage regulator or alternator overcharging. This may or nay not help, but it may get you thinking "outside of the box" so to speak. Are the lights really bright? do they get brighter when RPM goes up tec.? The only way ro really tell is to test the charging system and see what ya got. Or it could be a short, either way, if the bulbs a burning out it is from too much current flowing through them.
Tourer
Joined: Oct 2014
Posts: 378
Likes: 134
From: South Dakota
Do you mean the bulbs die right away even with the engine off or do they work before you start the engine? You can use a multimeter to measure the voltage at the bulb terminals inside the light socket (the "+" probe on the terminal, the "-" probe on a chassis ground point) - just be a little careful about shorting anything to ground with the positive meter probe when you are measuring.
If the bulbs don't die when the engine is not running then you may have an alternator issue but it seems that other bulbs would also be affected were that the case.
I'd suspect a ground issue - with the key off, measure continuity between the lamp ground in the socket and the battery negative terminal - it should be zero ohms.
You can also measure continuity from the socket to the connector pins - you need a schematic diagram to best do that.
Just out of curiosity, did you do any work on the bike before this problem started or did this just start happening out of the blue?
If the bulbs don't die when the engine is not running then you may have an alternator issue but it seems that other bulbs would also be affected were that the case.
I'd suspect a ground issue - with the key off, measure continuity between the lamp ground in the socket and the battery negative terminal - it should be zero ohms.
You can also measure continuity from the socket to the connector pins - you need a schematic diagram to best do that.
Just out of curiosity, did you do any work on the bike before this problem started or did this just start happening out of the blue?
Thread Starter
|
Road Warrior
Joined: Feb 2014
Posts: 1,851
Likes: 420
From: Santa Fe NM
Do you mean the bulbs die right away even with the engine off or do they work before you start the engine? You can use a multimeter to measure the voltage at the bulb terminals inside the light socket (the "+" probe on the terminal, the "-" probe on a chassis ground point) - just be a little careful about shorting anything to ground with the positive meter probe when you are measuring.
If the bulbs don't die when the engine is not running then you may have an alternator issue but it seems that other bulbs would also be affected were that the case.
I'd suspect a ground issue - with the key off, measure continuity between the lamp ground in the socket and the battery negative terminal - it should be zero ohms.
You can also measure continuity from the socket to the connector pins - you need a schematic diagram to best do that.
Just out of curiosity, did you do any work on the bike before this problem started or did this just start happening out of the blue?
If the bulbs don't die when the engine is not running then you may have an alternator issue but it seems that other bulbs would also be affected were that the case.
I'd suspect a ground issue - with the key off, measure continuity between the lamp ground in the socket and the battery negative terminal - it should be zero ohms.
You can also measure continuity from the socket to the connector pins - you need a schematic diagram to best do that.
Just out of curiosity, did you do any work on the bike before this problem started or did this just start happening out of the blue?
Trending Topics
Road Captain
Joined: Jul 2005
Posts: 578
Likes: 60
From: New Jersey
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Times Harley-Davidson Chucked Tradition Out the Window
Verdad Gallardo
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
Thread Starter
|
Road Warrior
Joined: Feb 2014
Posts: 1,851
Likes: 420
From: Santa Fe NM
Where do I go from here?
Ok so I checked with the harley dealer and I am getting the correct bulbs. I have continuity from the connectors forward to the bars, from the connectors back to the lights as well as directly in the light sockets. Everything is checking out fine. I also tested the wires from the bars back to the harness where the wires from both rear lights connect into the single connector. I really don't know what the problem is. Could it be that while washing the bike some moisture is getting into the light socket and causing a short at the bulb itself?
Also while testing in the light socket for continuity, I did it while the bike was running as well as off. While it was running the vibrations caused me to short circuit in the socket and it blew the fuse for the lights. If it was a short wouldn't that fuse have been blown before? I don't know where to go from here... I guess next step is to put bulbs back in it and see if they blow again? Anyone have any other suggestions?
Thanks to all who have given your thoughts and suggestions. They have been really helpful.
Also while testing in the light socket for continuity, I did it while the bike was running as well as off. While it was running the vibrations caused me to short circuit in the socket and it blew the fuse for the lights. If it was a short wouldn't that fuse have been blown before? I don't know where to go from here... I guess next step is to put bulbs back in it and see if they blow again? Anyone have any other suggestions?
Thanks to all who have given your thoughts and suggestions. They have been really helpful.
Tourer
Joined: Oct 2014
Posts: 378
Likes: 134
From: South Dakota
Specifically which bulbs are the problem - the rear turn bulbs? Are the fasteners that hold the light assemblies to the chassis tight? A lot of vibration will definitely kill bulbs quickly.
Last edited by John Ha; Jun 6, 2015 at 09:51 AM.