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My 2004 ST3 is still burning out taillights. I asked this of the forum about six months ago and was steered to a few things to check but everything checks out fine. Proper voltage from the regulator. Engine RPM is kept 5K +. All the grounds in the circuit seem fine. I have replaced the taillight assembly and harness to no avail. The taillight lasts a few hours then the next time I check it prior to a ride it is out. I am trying to find a way to install the Zeus fastener to the taillight lens because I have to remove it so often. I have bought a case of the 2357 bulbs and always have a few under the seat and a screwdriver in my pocket.

I am asking again because maybe a few different persons are passing through this forum that were not here a few months ago that have heard of this happening to other ST3s and know the fix. I am more than willing to replace the VR if necessary but prefer not to if it is not the problem. I had the motorcycle out one day last week and had to change the 2357 bulb prior to departure and just checked it and found it to be good. I know though that the life of the bulb is 2 - 3 trips then it burns out (taillight only... brake filament is OK).

I am beginning to think this is the reason that the guy had it for sale (I bought it used last September).

It is not much of a problem as I just keep my topcase on which has the tail and brake lighting kit installed. My dealer is stumped and Ducati hasn't heard of this as a widespread problem that they know anything about.

Thanks all.
 

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I would pull the bulb and check the contacts for proper voltage/amperage for the right filaments.

High Filament

Voltage: 12.8
Amps: 2.20
Watts: 28.2

Low Filament

Voltage: 14.0
Amps: 0.59
Watts: 8.3
 

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Bump

I know this thread is almost a year old, but my 2005 ST4s is exhibiting the same symptoms. Dangerous to ride at night w/o a running taillight. Today I'll be going for the 3rd one in just a few weeks.
 

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Try an inline resistor. We used to do this back in the day when cold bulbs blew fuses.

I recon 2 Ohm on the light and 5 on the Brake but someone may disagree
 

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My 2004 ST3 is still burning out taillights. I asked this of the forum about six months ago and was steered to a few things to check but everything checks out fine. Proper voltage from the regulator. Engine RPM is kept 5K +. All the grounds in the circuit seem fine. I have replaced the taillight assembly and harness to no avail. The taillight lasts a few hours then the next time I check it prior to a ride it is out. I am trying to find a way to install the Zeus fastener to the taillight lens because I have to remove it so often. I have bought a case of the 2357 bulbs and always have a few under the seat and a screwdriver in my pocket.

I am asking again because maybe a few different persons are passing through this forum that were not here a few months ago that have heard of this happening to other ST3s and know the fix. I am more than willing to replace the VR if necessary but prefer not to if it is not the problem. I had the motorcycle out one day last week and had to change the 2357 bulb prior to departure and just checked it and found it to be good. I know though that the life of the bulb is 2 - 3 trips then it burns out (taillight only... brake filament is OK).

I am beginning to think this is the reason that the guy had it for sale (I bought it used last September).

It is not much of a problem as I just keep my topcase on which has the tail and brake lighting kit installed. My dealer is stumped and Ducati hasn't heard of this as a widespread problem that they know anything about.

Thanks all.
For shits and giggles, I would disconnect the front harness from the rear harness and check for corrosion and any melting of the connector/contact face's. My ST had all sorts of electrical issues, and this is where we found the problem.
 

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+1 on tracing the wiring back for rusted grounds, potential shorts, melted insulation, etc.

Is it maybe poor quality replacement bulbs? Try a different brand? Worst case wire a red led setup into the factory taillight?
 

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Discussion Starter #8
I have had the same bulb in there for a while now and it is still burning strong. It is one of those LED (18 of them) bulbs. I really did not do anything to troubleshoot except take apart the rear light harness connector that did not have any trace of corrosion. Go Figure.

Good luck with getting your ST4s fixed.
 

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Myself and a friend both have ST3's and have the same problem. The way we solved it was getting an LED tail light from the Auto parts store about $10 i haven't burned a bulb in over a year.

Pete,
 

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Myself and a friend both have ST3's and have the same problem. The way we solved it was getting an LED tail light from the Auto parts store about $10 i haven't burned a bulb in over a year.

Pete,
This isn't solving a problem, it's just masking it. It's no different a solution than saying, "Put a bigger fuse in".
 

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Quote:
Originally Posted by Monster800 View Post
Myself and a friend both have ST3's and have the same problem. The way we solved it was getting an LED tail light from the Auto parts store about $10 i haven't burned a bulb in over a year.

Pete,
This isn't solving a problem, it's just masking it. It's no different a solution than saying, "Put a bigger fuse in".

Well we did check the wires thoroughly and found nothing so I believe that the bulbs maybe blowing due to vibration. I put in a heavy duty bulb which did last but changed over to LED to eliminate the problem for good.:)
 

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I think the LED bulb is a creative solution. It will definitely resist vibrations that an incandescent light bulb cannot.

I do find it strange, though, that a few ST machines exhibit this problem. I put over 50,000 miles on the ST2 and never touched the rear bulb. My ST4s has 23,000 miles on it with the factory bulb.

And I do like the idea of supplementing the original bulb with a separate array of LEDs, like in the outter portions of the lens. That way, you wouldn't be depending on a sole element back there.

I fashioned up the front turn indicators with LEDs on my ST4s in an attempt to create DRLs (daytime running lights). They work, but not as bright as I had hoped. I've been wanting additional lighting in the rear, and this sounds like a reasonable thing to do...

Also note, that if the harness had some connection problems (corrosion), this would reduce the voltage to the bulb, and theoretically, would make it last longer. I have a feeling it's a vibration issue.

Maybe it's the bigger front fairing on the newer ones setting up some kind of harmonic vibration...
 

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I think the LED bulb is a creative solution. It will definitely resist vibrations that an incandescent light bulb cannot.

I do find it strange, though, that a few ST machines exhibit this problem. I put over 50,000 miles on the ST2 and never touched the rear bulb. My ST4s has 23,000 miles on it with the factory bulb.

And I do like the idea of supplementing the original bulb with a separate array of LEDs, like in the outter portions of the lens. That way, you wouldn't be depending on a sole element back there.

I fashioned up the front turn indicators with LEDs on my ST4s in an attempt to create DRLs (daytime running lights). They work, but not as bright as I had hoped. I've been wanting additional lighting in the rear, and this sounds like a reasonable thing to do...

Also note, that if the harness had some connection problems (corrosion), this would reduce the voltage to the bulb, and theoretically, would make it last longer. I have a feeling it's a vibration issue.

Maybe it's the bigger front fairing on the newer ones setting up some kind of harmonic vibration...
I'll pimp PG's LED taillight:

http://ducatidesigns.com/inc/sdetail/2497
 

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Discussion Starter #15
I don't see myself spending $109.00 on a taillight bulb when there is the potential that I could burn it out just like the other dozen bulbs I have installed. Like I said before I have not entirely solved the "taillight burning out issue" but only masked it by installing a cheapo LED bulb that is inherently more resistant to voltage/current spikes/surges. So far this cheapo solution has been OK for the past year.

The maker of the ducati design $109.00 taillight is aware that there are 2004 ST3s that are going through multiple taillight bulbs and they do not recommend installing their unit unless the underlying cause is determined. Which nobody has yet. My dealer (DucPond) does not know of a solution to this problem but is aware of it.
 
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