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1994 Ducati Super Sport 900 CR
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Discussion Starter #1
Hi Everyone, I just picked up my first Ducati, its a 1994 Super Sport and i am STOKED! On the way home from the sellers my wife noticed i didn't have any lights on the rear tail light at all (no running lights, no brake lights). The first thing i thought of was the bulb was burned out....simple. No, not simple. I replaced the bulb with a 2 filament 1157 i bought new. Now, the brake lights on all the time (both filaments are lit). So i thought, hey, one of the micro switches for the front brake lever or the rear must be stuck in ON position. So, I started to disassemble the areas to gain access to the switches. I did so (after breaking a bolt off on the rear peg set :(!. Anyways, here's where it gets interesting. So with the rear switch in the OFF position (not braking) and the front switch in the OFF position (not braking) the tail light is still on...both elements. With the rear switch in the OFF position and the front in ON position (when you'd squeeze the lever to brake) one element will turn off on the tail light. I checked to ensure i'm inserting the bulb correctly. The rear switch will very faintly try to cut out the second element in the ON position but is really ineffective. Oddly, the receptacle for the rear bulb has 3 slots, the 1157 has 2 slots. Any help is appreciated as riding without brake lights isn't an option:)
988789
 

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Original bulb was not an 1157 but years ago they were close enough to work. Now they make the bulbs smaller and they do not seat properly in the bulb socket. The brass tabs are crap, the spring is crap and to make it worse -- one "nub" on the 1157 bulb is lower than the other which means it might work in your driveway but fail 10 minutes later because it won't stay in place. And yeah, if you have the nubs on the wrong tabs you get the brake light on all the time while it makes contact or nothing at all.

Good news for when the cop pulls you over, practice tapping it in just the right spot and it will come on.

Fight with it all you want but unless you can find an old stock 1157 made 10 years ago you won't win.

You can drill out the lamp holder and install an aftermarket unit. I've done it twice and it isn't an easy process, however it can work. My local auto parts store sells these generic 1157 bulb holders that have wires and a spring under them that push them onto the bulb. A much better version. Basically I drill out the original bulb holder and slide in the new style with some epoxy to hold it in place, then connect the wires. A change to a modern LED is a great option, 20x as bright, and the generic 1157 holder is made for the new smaller size bulb.

When I got new bodywork recently, solo tail, new options opened up and I bought a modern LED assembly to replace the whole contraption keeping it as a spare for the other bike.
 

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I tried to replace the rear bulb with an LED bulb and the brake light stayed on.
I think I have an old Stanley bulb out of a Suzuki in it now.
I think RockAZ is on to something, it’s Probably socket related.
 
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1994 Ducati Super Sport 900 CR
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Discussion Starter #4
Original bulb was not an 1157 but years ago they were close enough to work. Now they make the bulbs smaller and they do not seat properly in the bulb socket. The brass tabs are crap, the spring is crap and to make it worse -- one "nub" on the 1157 bulb is lower than the other which means it might work in your driveway but fail 10 minutes later because it won't stay in place. And yeah, if you have the nubs on the wrong tabs you get the brake light on all the time while it makes contact or nothing at all.

Good news for when the cop pulls you over, practice tapping it in just the right spot and it will come on.

Fight with it all you want but unless you can find an old stock 1157 made 10 years ago you won't win.

You can drill out the lamp holder and install an aftermarket unit. I've done it twice and it isn't an easy process, however it can work. My local auto parts store sells these generic 1157 bulb holders that have wires and a spring under them that push them onto the bulb. A much better version. Basically I drill out the original bulb holder and slide in the new style with some epoxy to hold it in place, then connect the wires. A change to a modern LED is a great option, 20x as bright, and the generic 1157 holder is made for the new smaller size bulb.

When I got new bodywork recently, solo tail, new options opened up and I bought a modern LED assembly to replace the whole contraption keeping it as a spare for the other bike.
Thanks Rock. The socket replacement sounds like the way to go. Ill keep you guys Updated
 

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1994 Ducati Super Sport 900 CR
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Discussion Starter #5
I tried to replace the rear bulb with an LED bulb and the brake light stayed on.
I think I have an old Stanley bulb out of a Suzuki in it now.
I think RockAZ is on to something, it’s Probably socket related.
Yessir, that sockets gotta go!
 

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Check your ground wire, too. If it's not making contact the power wires (brake and tail) may be using each other to complete the circuit.
 
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The pic in the other thread on the peg shows a bad condition of the engine ground strap, if the other ground is as bad of shape that will make the brake lights goofy.
 

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1994 Ducati Super Sport 900 CR
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Discussion Starter #8
Check your ground wire, too. If it's not making contact the power wires (brake and tail) may be using each other to complete the circuit.
Thank you, thats atrip they would do that! You mean the harness ground?
 

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i would suggest cleaning every single electrical connection on the bike. i use an electrical contact grease on all connections --i know there are some that do not like to put grease on the connectors --but the stuff i use stops any and all corrosion i even put a little on the contacts of light bulbs--i have zero issues with dirty contacts
 
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I tried to replace the rear bulb with an LED bulb and the brake light stayed on.
I think I have an old Stanley bulb out of a Suzuki in it now.
I think RockAZ is on to something, it’s Probably socket related.
The smaller bulb diameter on the metal part is not big enough to ground reliably, it doesn't touch the sides of the socket holder, intermittent contact is no good.
 

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1994 Ducati Super Sport 900 CR
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Discussion Starter #11
i would suggest cleaning every single electrical connection on the bike. i use an electrical contact grease on all connections --i know there are some that do not like to put grease on the connectors --but the stuff i use stops any and all corrosion i even put a little on the contacts of light bulbs--i have zero issues with dirty contacts
Thank you Renn, will go through and check everything. I'll update you guys when I get this resolved!
 

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Discussion Starter #12
The smaller bulb diameter on the metal part is not big enough to ground reliably, it doesn't touch the sides of the socket holder, intermittent contact is no good.
Yes absolutely. I was going to go the route of checking and securing all grounds. If its not resolved after that im going to switch the bulb recptacle with a newer style. I'll probably 3d print the reflector. If I do Ill post the design for anyone else to use
 

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No need to replace the reflector, get the 1157 pigtail socket and you will see how it could go together. Just two drops of epoxy or superglue will hold it. There are usually two levels of quality available so get the better one. It might even say water resistant for use in a boat trailer.

In the meantime, go steal an 1157 bulb from an old car at your grandad's house or junkyard.
 

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Discussion Starter #14
No need to replace the reflector, get the 1157 pigtail socket and you will see how it could go together. Just two drops of epoxy or superglue will hold it. There are usually two levels of quality available so get the better one. It might even say water resistant for use in a boat trailer.

In the meantime, go steal an 1157 bulb from an old car at your grandad's house or junkyard.
Righteous, sounds 👍
 

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Thank you, thats atrip they would do that! You mean the harness ground?
Yes, check the ground wire at the bulb socket to ensure it is making contact with the bulb and a good contact where it attaches to the frame.
 
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Just switch the two wires around. I bet the tail light is wired into the brake light and vice versa.
 
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I said it earlier but I guess I should say it again: there are two wires that go to the tail light assembly. One wire is to the brighter brake light and one is to the dimmer tail light. If the tail light wire is directed to the brake light, the brake light will illuminate when the bike is turned on. When you apply the brake, the tail light bulb will illuminate but because it's dimmer than the brake light, it's hard to see.

I would investigate that first before doing anything else.
 
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I said it earlier but I guess I should say it again: there are two wires that go to the tail light assembly. One wire is to the brighter brake light and one is to the dimmer tail light. If the tail light wire is directed to the brake light, the brake light will illuminate when the bike is turned on. When you apply the brake, the tail light bulb will illuminate but because it's dimmer than the brake light, it's hard to see.

I would investigate that first before doing anything else.
Yes this is part of the issue, it also loses grounding contact with the sides of the bulb holder which results in no lights. It twists around inside the socket while the bike is in motion, it will work in the driveway, but the nubs will not maintain their position and eventually either switch or go off. And part of the problem is the really shitty design of the spring loaded contact. The older 1157 bulbs were slightly larger and definitely heavier which is why they work pretty well. Most modern 1157 bulbs do not fit well in the socket made for the original different Euro spec ( P21w/5w BAY15d ,15 mm, axially offset pins as opposed to radially offset pins).

Replacing the bulb socket with a good quality one along with using a modern LED bulb is the long term solution. I did find a specialty LED bulb in red that fit rather well in the OEM socket, but that was because I bought the entire new old stock taillight assembly from Ducati of Omaha. The spring at least was stronger and the contact points scooped along with radially offset pin slots.
 

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Just throwing this out, but would it be possible to add a small drop of solder to the bulb in the location where it is not properly contacting to increase its size?
 
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