Non functioning tail light, MultiStrada 950

[Derek]

It sees to me that since both the taillight and the number plate light aren't working and the only thing common to both is the supply then that is where the fault lies.. they won't both fail simultaneously. I think the earth can be discounted because the brake light wouldn't work either. It seems simple enough to check the input voltage with a meter and if it isn't there then the BBS must be at fault. With the tail light and number plate disconnected 12V could be applied to them to check their function.

 

[West Cork Paul]

Just an aside Paul, the wiring diagrams we get are usually very good, so your post made me think.... I've checked this morning and mine is correct. Looks the same, but the legend as to what is what is correct on the one I have. Where are you getting the diagrams from? Poor info on them will cause you even more problems..

Absolutely. First I got a wiring diagram from the owners manual but couldn’t find a legend for it, then I got a wiring diagram from rmi.ducati and it’s legend but the diagram was so small when printed off on A4 (can’t do bigger on my printer) I made a fateful mistake and used the legend from rmi with the diagram from the OM which was more legible. However, the diagram in the OM has different numbering to that from rmi hence me having to make changes. Once I’d worked out what was going on and the mistake I’d made all was clear . Stupid user error .

 

[West Cork Paul]

It sees to me that since both the taillight and the number plate light aren't working and the only thing common to both is the supply then that is where the fault lies.. they won't both fail simultaneously. I think the earth can be discounted because the brake light wouldn't work either. It seems simple enough to check the input voltage with a meter and if it isn't there then the BBS must be at fault. With the tail light and number plate disconnected 12V could be applied to them to check their function.

Yep, if I feed the supply cable to the tail light with 12v directly the light comes on so at least I know that unit isn’t faulty.

However, the problem is now fixed and I will explain how later, once I’ve got over my embarrassment .

 

[Noobie]

 

[Ger]

..............

 

[West Cork Paul]

I needed that after I discovered my faux pas

 

[Noobie]

Come on then, what was it

 

[The skitz]

 

[West Cork Paul]

Come on then, what was it

 

[West Cork Paul]

In a pathetic attempt to come up with some sort of excuse the fuse in question was marked ‘Lamps’ and as the headlights were working I didn’t pull it and check it but did pull and check the one for the BBS and a few others. Duhhhh, just because the fuse says Lamps doesn’t mean it’s for the headlamps . I guess he blew it when attempting to fit the ST2 brake module.

 

[West Cork Paul]

Anyway, moving swiftly along, all fixed, now, plus a non-functioning clutch switch issue cured ie he couldn’t start the bike in gear with the clutch lever pulled back to the bars. Mainly because the bike had Oxford heated grips, not OEM, and the owner had fitted different brake & clutch levers which, thanks to the positioning of the heated grips could not be fully retracted to the bar.

This is the brake lever, the clutch was the same until I realigned the heated grip. I couldn’t realign the RH heated grip as it appears to have been glued to the throttle tube. Fortunately full braking efficacy comes into play before the lever touches the heated grip but I have pointed out to him that may not always be the case.

 

[West Cork Paul]

Reverting to my earlier thoughts, perhaps those with a better understanding of electronics than me can offer up their thoughts.

As mentioned above the ST2 brake module works by being spliced into a 12v feed (usually the supply to the rear light cluster), an earth cable and it has a signal output wire that’s spliced into the feed to the stop light be they regular 12v bulbs or LEDs. It’s constantly powered when the key is on and detects deceleration under engine braking and then sends a pulse of 12v down its signal wire to light up the stop light. This can be a continuous pulse, ie turning on the stop light, or can be a series of pulses, ie causing the stop light to flash.

Clearly that pulse of 12v will go both ways along the cable it’s spliced into. With a traditional wiring configuration the 12v will go to the light, whic is earthed and illuminates and to the original brake switch which is a mechanical device. Nothing too technical there.

However, when the lights are actually controlled by a computer, the BBS, which normally receives a signal from the brake switch on one pin and as a consequence then fires 12v down another pin to the tail light, each time the ST2 pulses its going to be sending 12v back into the BBS from a direction and source it’s not expecting it.

Is there not a risk that might damage the BBS?

 

[Ger]

Well .....I'd be nervous about splicing anything into a "lamp" circuit coming out of expensive black boxes. Not a fan of those insulation displacement splice connectors either Paul .......

I'm guessing it's against MOT to provide this well meaning ST2 device with it's own small red led light on the tail of the bike .... I do quite like the idea of the deceleration flashing light.

 

[Derek]

Reverting to my earlier thoughts, perhaps those with a better understanding of electronics than me can offer up their thoughts.

As mentioned above the ST2 brake module works by being spliced into a 12v feed (usually the supply to the rear light cluster), an earth cable and it has a signal output wire that’s spliced into the feed to the stop light be they regular 12v bulbs or LEDs. It’s constantly powered when the key is on and detects deceleration under engine braking and then sends a pulse of 12v down its signal wire to light up the stop light. This can be a continuous pulse, ie turning on the stop light, or can be a series of pulses, ie causing the stop light to flash.

Clearly that pulse of 12v will go both ways along the cable it’s spliced into. With a traditional wiring configuration the 12v will go to the light, whic is earthed and illuminates and to the original brake switch which is a mechanical device. Nothing too technical there.

However, when the lights are actually controlled by a computer, the BBS, which normally receives a signal from the brake switch on one pin and as a consequence then fires 12v down another pin to the tail light, each time the ST2 pulses its going to be sending 12v back into the BBS from a direction and source it’s not expecting it.

Is there not a risk that might damage the BBS?

Probably not. But a diode in line with the supply to the ST2 would prevent any voltage going back to the BBS. There would be a slight drop of 0.7V across the diode but probably wouldn't affect the operation of the ST2 unit.

 

[Ger]

One thing I would do if you're going to try to get it working......set it up off the bike on the bench with a DC supply and see if it works ok ......shove a suitable fuse in the supply just in case it has a problem .....

You need a bench supply again Paul ....

 

[Ger]

Probably not. But a diode in line with the supply to the ST2 would prevent any voltage going back to the BBS. There would be a slight drop of 0.7V across the diode but probably wouldn't affect the operation of the ST2 unit.

I wonder if ST2 tech support would know if there's any steering diodes in the output of the module Derek....?...

 

[Alan Williams]

Could the pulse function be what takes the fuse out ?
Perhaps it creates a surge that the fuse can’t cope with.

 

[West Cork Paul]

Could the pulse function be what takes the fuse out ?
Perhaps it creates a surge that the fuse can’t cope with.

That thought went through my mind but they’re different circuits. The module sends its pulse of 12v down the stop light wire which, on this bike, is a different circuit to that from which it draws its power and on which the 5A fuse blew.

I suspect the owner short circuited something when he was installing the snap on splices but who knows . He just told me he installed it, tried to test it and found it didn’t work but then neither did his tail light anymore.

Anyway I fitted a new fuse, gave him a spare and advised that if it was my bike I wouldn’t fit it but it’s up to him to try again if he wants.

He’d also bought the ST2 indicator module and was going to fit it but yet again the rear indicators are fired by the BBS so I advised not to for now.

 

[Ger]

That thought went through my mind but they’re different circuits. The module sends its pulse of 12v down the stop light wire which, on this bike, is a different circuit to that from which it draws its power and on which the 5A fuse blew.

I suspect the owner short circuited something when he was installing the snap on splices but who knows . He just told me he installed it, tried to test it and found it didn’t work but then neither did his tail light anymore.

Anyway I fitted a new fuse, gave him a spare and advised that if it was my bike I wouldn’t fit it but it’s up to him to try again if he wants.

He’d also bought the ST2 indicator module and was going to fit it but yet again the rear indicators are fired by the BBS so I advised not to for now.

Right thing to do Paul ........

 

[WAYNE]

 

[West Cork Paul]

I'm guessing it's against MOT to provide this well meaning ST2 device with it's own small red led light on the tail of the bike ..

No MOTs for bikes here in ROI so that’s not an issue but they don’t supply it anyway, mind you, could always rig up something else.

 

[West Cork Paul]

Probably not. But a diode in line with the supply to the ST2 would prevent any voltage going back to the BBS. There would be a slight drop of 0.7V across the diode but probably wouldn't affect the operation of the ST2 unit.

Wouldn’t the diode have to be in line with the signal wire in the direction of the BBS rather than in the supply wire? The supply wire just takes 12v in to power the module.

I wonder if ST2 tech support would know if there's any steering diodes in the output of the module Derek....?...

. I emailed ST2 on Wed to ask if it was compatible with the 2017 Multi 950. They’re based in some Eastern European country. I got a reply within the hour telling me of course it is compatible, there was a link in the email to ‘buy now’.

Wed eve I got another email extolling me to purchase.

Thurs am I got another and again Thurs eve I got another but offering me 10% discount this time.

Fri am I got an email offering me 15% off if I buy now. Fri eve’s email offered 25%.

This morning, Saturday, I saw another email confirming it’s compatible, sent at 02.04hrs. Again there’s a Buy Now link, this time is 33% off.

I suspect there’s more focus on sales than customer support and a question such as that about the diode most likely would never get answered. However, I may be doing them a disservice so I shall ask the question.