Author Topic: Tail light  (Read 519 times)

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Malvo

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on: June 11, 2024, 08:23:24 am
Hello everyone.

I am writing this post in search of a answer for a issue i have been having.

Basicaly when the bike is running and i apply the brakes, the tail light goes out.

If i slap the tail light it normally turns on again, but as soon as i brake, either front or rear break it goes out.

It happens ONLY when its running, if i Turn the Key and dont turn the bike on, nothing happens.

I already changed the RR unit, as i was having issues with the ABS light turning on etc, and i thought this could BE related, but its as persisted.


The last bulb i changed was white, like its was getting really hot.

Could it bem shorting?
Fuse or some sorte of relay issue?

Any ideas?
Any input would be greatly appreciated.

Thanks you for the help.


TSTM

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Reply #1 on: June 11, 2024, 02:26:40 pm
Bad ground connection in/around your taillight?
'22 Continental GT 650

previous bikes
Yamaha XS650
Honda Shadow VLC
Moto Guzzi California 1100
Maico 490 dirtbike


Knacker

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Reply #2 on: June 11, 2024, 05:50:01 pm
My GT has eaten 2 taillight bulbs in 17,000 miles. In both cases, a filament failed (tested the bulbs with a meter). Interestingly, in both cases, rapping on the taillight assembly would get the bulb working again, temporarily.

So not exactly the same issue, but seeming to indicate vibration is not well enough controlled.

I'd toss in a new, brand name bulb with some dielectric grease and see what happens. Beyond that you're chasing a bad connection, sadly.

I'm now in the habit of checking tail and brake light function at each startup.


Malvo

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Reply #3 on: June 12, 2024, 08:14:59 am
Thank you for the replies.

I wonder if it could simply be a bad earth, heck even a ignorant dude like me could probably check it by myself.

I will try and find out were the earth connections are, and check them out myself.

Initially i thought it could be a vibration issue, like Knacker said, i tried testing it, trying several things to secure the bulb, i even tried some tape around the base of the bulb, nothing worked... The wierdest think happened when i got it from the shop the first time, it would work great for a few days regardless of the type of road i used, and vibrations it would produce, so i assumed that vibration are nor to blame.
Then out of the blue, after a few rides/days it would start again...

Well going to start with the earth connections.

Thanks you for the help and the tips.


YellowDuck

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Reply #4 on: June 12, 2024, 02:30:13 pm
I'm now in the habit of checking tail and brake light function at each startup.

Excellent practice.  Thanks for the reminder.


TSTM

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Reply #5 on: June 12, 2024, 08:26:43 pm
Thank you for the replies.

I wonder if it could simply be a bad earth, heck even a ignorant dude like me could probably check it by myself.

I will try and find out were the earth connections are, and check them out myself.

Initially i thought it could be a vibration issue, like Knacker said, i tried testing it, trying several things to secure the bulb, i even tried some tape around the base of the bulb, nothing worked... The wierdest think happened when i got it from the shop the first time, it would work great for a few days regardless of the type of road i used, and vibrations it would produce, so i assumed that vibration are nor to blame.
Then out of the blue, after a few rides/days it would start again...

Well going to start with the earth connections.

Thanks you for the help and the tips.

Could be as simple as a bad ground contact between the bulb and the taillight.

A defective bulb because of vibration could also be related to a bad connection.
The firlament (spiral) of the bulb is in fact a coil. The current trough the coil results in a magnetic field, which in turn stabilizes the firlament.
A bad connection means less current, less magnetic field, less stabilization, therefore more vulnerable for vibration.
« Last Edit: June 12, 2024, 08:32:12 pm by TSTM »
'22 Continental GT 650

previous bikes
Yamaha XS650
Honda Shadow VLC
Moto Guzzi California 1100
Maico 490 dirtbike


Greyhound

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Reply #6 on: June 12, 2024, 09:33:53 pm
Could be as simple as a bad ground contact between the bulb and the taillight.

A defective bulb because of vibration could also be related to a bad connection.
The firlament (spiral) of the bulb is in fact a coil. The current trough the coil results in a magnetic field, which in turn stabilizes the firlament.
A bad connection means less current, less magnetic field, less stabilization, therefore more vulnerable for vibration.

First thing you can do is simply use a test light to check for proper/constant voltage at the tail light harness under the seat.

Unplug the tail light harness, connect the clip of the test light to a solid earth/ground and stick the needle end of the test light into the port on the harness corresponding to the brake light.

This will indicate whether the bad connection is before or after this harness (hopefully it’s after aka on the tail light side, which should be a very easy fix).


Greyhound

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Reply #7 on: June 12, 2024, 09:40:37 pm
In case you’re unfamiliar… This is a test light, costs around $10-$15

I like the type that also have a built in voltmeter, and if you really want to get fancy… some have a red or green indicator for positive or ground/earth in case you want to swap polarity.



TSTM

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Reply #8 on: June 13, 2024, 09:23:23 am
Chances are this ^^^ is gonna give you false information.
If you have a bad connection, there will flow enough current to light up the test light

He described that the taillight works, but all dims as soon as he hits the brakes
This tells us the connection is good enough for 5W, but not good enough for 5W + 21W.

If you use a test light, be sure to also use it with the bulb in place, to simulate a loaf.
You can also use a voltmeter.
There should be 12V, with the bulb in place.

Another possibility is to tak a wire, ground it somewhere on the bike en touch the ground of the bulb
Then work your way back to the source  touch the ground of the taillight, touch the ground of the connector etc.
But be careful not to touch the positive wire :-\
'22 Continental GT 650

previous bikes
Yamaha XS650
Honda Shadow VLC
Moto Guzzi California 1100
Maico 490 dirtbike


Malvo

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Reply #9 on: Yesterday at 08:51:49 pm

Hey everyone.

So... well it is sorted.

Last week I just had a couple of hours, and around Thursday I went to the garage to do a "light check".

Also my old man was around (he's been around electricity all is life, and made is living repairing appliances, and all sorts of stuff), so I asked him to give me a hand and see if we could sort it out.

I checked the battery, and the voltage with the bike off and on was stable and within parameters.

Then we did an "easy earth check" with a multimeter, red on the battery, black on the frame, and got an easy stable reading, so basically the earth connection was good.

I checked the light connector under the seat, took it off, did some light cleaning (well, I blew on it a bit), and put it back together. No dirt, no dust, no grime, nothing. One thing that I saw was that the wire that connected to the tail light was stuck between the fender and the frame, next to the right shock, and it was really stuck. The wire was bent quite badly.
Sort it out with a zip tie.

I finally checked the tail light. I took the bulb out, checked the socket, and it seemed nice and clean, but I saw something i didn't see before, what looked like dirt between the socket and the reflector. Oxidation. But the inside of the socket was good.

Then my old man picked up a screwdriver, put a cloth around it, and he sort of lightly scratched the contacts... I closed everything, turned the bike on, the light came up, and it's been running great ever since...

Well it's sorted, can't say if it had something to do with the stuck wire, or just the contacts...

I sort of feel stupid, but I learned a few things from the old man. I just have to pay more attention to the little details, like the bent wire, and even if it's simple and silly, if I have done it already, do it and check it again just in case!

Thank you, guys, for the replies, suggestions and tips.


Bumbo

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Reply #10 on: Today at 10:16:21 am
Check the wiring harness under the rear mud guard


deadbat

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Reply #11 on: Today at 10:37:05 am
Hey everyone.

So... well it is sorted.

Last week I just had a couple of hours, and around Thursday I went to the garage to do a "light check".

Also my old man was around (he's been around electricity all is life, and made is living repairing appliances, and all sorts of stuff), so I asked him to give me a hand and see if we could sort it out.

I checked the battery, and the voltage with the bike off and on was stable and within parameters.

Then we did an "easy earth check" with a multimeter, red on the battery, black on the frame, and got an easy stable reading, so basically the earth connection was good.

I checked the light connector under the seat, took it off, did some light cleaning (well, I blew on it a bit), and put it back together. No dirt, no dust, no grime, nothing. One thing that I saw was that the wire that connected to the tail light was stuck between the fender and the frame, next to the right shock, and it was really stuck. The wire was bent quite badly.
Sort it out with a zip tie.

I finally checked the tail light. I took the bulb out, checked the socket, and it seemed nice and clean, but I saw something i didn't see before, what looked like dirt between the socket and the reflector. Oxidation. But the inside of the socket was good.

Then my old man picked up a screwdriver, put a cloth around it, and he sort of lightly scratched the contacts... I closed everything, turned the bike on, the light came up, and it's been running great ever since...

Well it's sorted, can't say if it had something to do with the stuck wire, or just the contacts...

I sort of feel stupid, but I learned a few things from the old man. I just have to pay more attention to the little details, like the bent wire, and even if it's simple and silly, if I have done it already, do it and check it again just in case!

Thank you, guys, for the replies, suggestions and tips.

Great result, thanks for the updates.
2022 RE Interceptor 650