Safety Alert for 8V Motors. Possible Alternator Wiring Issue

[canuck1969]

All,

This could easily be an issue on any other 8V motor so not specific to the Stelvio.

One of the members on the forum (I will leave it to him if he wants to be identified) contacted me via PM on another forum as he had a charging issue with his bike. SInce I had laid out the electrics in a previous thread he thought I could help him with fixing his bike.

Symptoms

• Had no headlights, high beam or low beam with the bike running, however from time to time they would come on.
• No charging with headlights on or off
• This continued sporadically for some time but the bike never died or left him stranded.
• Replace the battery with a MotoBatt but the problems still continued
• Had the obligatory no head lights, no charging and blue HB light when the momentary HB switch was pulled.
• 30 amp fuse was good.

At that time we suspected a faulty relay and he replace both the HB and LB relays with Bosch relays. The problems still continued. Over email, I requested the voltages to be measured at the relays as per my previous thread concerning the voltage sequencing of the HB and Lighting relays.

Voltages on terminal 30 and 87 on the lighting relay were sporadic. Voltage one minute, no voltage the next. Even when 30 (main relay power from 30 amp fuse) and 87 (exciter power and lighting power) had power there was no charging or lights which at that time seemed impossible for the lights as 87 is pretty much a direct line to the lights as long as the HB relay is working (and it was confirmed as working)

At this point I was intrigued and packed up my tools and electrical diagnostics and repair items. Luckily he was only an hour ride from my place.

I spent a hour or so testing and retesting the paths and nothing made sense at that time. The most curious thing was that when the bike was running, the power to the 30amp fuse (and therefore the lighting relay) was gone. When it was just the key on, the power was there.

• Tested resistance of the 30 amp fuse power supply wire (red green) to the +ve on the battery and it had continuity (0.1 ohm resistance)
• Tested continuity of the 40 amp fuse power supply (green/red) that is for the charging power to the +ve on the battery and it had a resistance of 280 ohm. This should be zero to the battery.
• Tested continuity between the above two wires which are spliced together as some point (brings battery power and charging power to the bike) and had continuity.
• Jumped power to the 30 amp fuse directly from the battery which powered the 87 terminal on the lighting relay (ie. power to headlights and alternator exciter) and the headlights came on when the bike was running, but no charging. 

At this point we removed the tank. I tested continuity from the main power lead on the alternator to the battery and it had continuity. After scratching my head as it made no sense, I pull the boot back on the terminal and tested it again. Now it didn't have continuity. Wiggling the wire produced an on/off on continuity. I gave a small tug on the wire from the boot and out it came with a crunch and burnt copper wire everywhere. The member has photos of the wire and terminal.

Turns out the splice between the 40 amp and 30 amp fuses is at the actual alternator. Both wires are crimped into a ring terminal that is screwed to the alternator. The ring terminal insulation was completely burnt along with about 2 inches of wire. Turned it to dust.

Had just enough connection to give readings when the key was on, but once the bike was started and the vibrations set in, the connection was broke. This resulted in increased resistance and a crap load of heat. If this had continued and not broken completely when the bike was running it would have resulted in a meltdown under the gas tank. He did say that he swore he saw some puffs of smoke on the last ride by though he was imagining things, as we all have. The crimp on the ring terminal was marginal at best. I am not even sure it was there to begin with. This was not a corrosion issue as the wires themselves and the insulation were completely burnt. There is also nothing to ground to where these wires are and they are protected by a long boot so it was not a small short to ground

Installed a new ring terminal and made sure the crimp was secure. Fired up and had full charging and lights.

This is something to be aware of it you start to have charging and light issues and the 30amp fuse and relays are still good. Easiest check is to check the resistance between the 30 amp red/green wire (one behind the right hand panel under the seat) and the 40 amp red green wire (40 amp next to the air box). It should be pretty much 0 to 0.1 ohm. Then check the resistance of each of those wires to the +ve on the battery. Should again be 0 to 0.1 ohms. Any resistance much higher than those numbers (subtracting the resistance of the actual meter wires) indicate a problem developing and you should be checking that connection at the alternator.

Thanks

Joe

[pete roper]

Good find, noted.

Pete

[lti_57]

I don't have an 8 Valve.
But still good to know thanks

[azguzzirep]

You deserve an "ATTA BOY"! 😆

[normzone]

A well written report, thank you.

[pete roper]

Thinking about this further it almost certainly applies to all CARC bikes with the hi-mount alternator so all of 'em apart from the Bellagio.

Pete

[canuck1969]

Thinking about this further it almost certainly applies to all CARC bikes with the hi-mount alternator so all of 'em apart from the Bellagio.

Pete

Could very well be Pete.  You know the other bikes better than I do.  I really think the issue here was a bad crimp on the two wires on a standard ring terminal.  Easy to mess up if not paying attention when someone made up the wiring harness.  If those other bikes also have the two wire setup it can happen again.  I would have rather had the 30 amp circuit have a dedicated feed directly to the battery as it is so important in the operation of the bike.  It would still work if that was done as the current would just balance at a different point between charging and battery power.

I wish I had investigated the terminal and wires a little closer for a root cause.   Was shocked to see it and was just determined to get the bike working again for the owner.  He still has the terminal and wires and some pics.  Will try to get them or he may post them on the site.

Either way, something to keep an eye out for.  May never happen again on a bike, but one never knows.  Mistakes are rarely a one time occurrence in manufacturing.

[Johncolleary]

Shortly after I bought my 2013 Stelvio the headlight became intermittent had it back to the dealer several times.  they finally took it to the Piaggio tech center and they had the dealer replace the entire wiring harness.  solved the issue.  I would liked to have had a chance to examine the harness to see where the failure occurred.

[canuck1969]

Shortly after I bought my 2013 Stelvio the headlight became intermittent had it back to the dealer several times.  they finally took it to the Piaggio tech center and they had the dealer replace the entire wiring harness.  solved the issue.  I would liked to have had a chance to examine the harness to see where the failure occurred.

This too was a 2013 Stelvio. Your right would be really good to see that harness. Only so many wires that affect the lights.   

[rodekyll]

The description leaves me wondering if an internal alternator/regulator fault gave a dead short down that wire.  The part about how badly it burned and the puff of smoke (maybe) suggests battery voltage straight to ground -- that instantaneous "flame on" down the length of the wire.  It's difficult to crispy fry an alternator wire from intermittent high resistence.  The heat would explain the marginal crimp better than a marginal crimp explains the damage for the entire length of the wire.  I would expect a bad crimp to burn in a more localized way.

Just an alternative scenario from someone who wasn't there.

[canuck1969]

The description leaves me wondering if an internal alternator/regulator fault gave a dead short down that wire.  The part about how badly it burned and the puff of smoke (maybe) suggests battery voltage straight to ground -- that instantaneous "flame on" down the length of the wire.  It's difficult to crispy fry an alternator wire from intermittent high resistence.  The heat would explain the marginal crimp better than a marginal crimp explains the damage for the entire length of the wire.  I would expect a bad crimp to burn in a more localized way.

Just an alternative scenario from someone who wasn't there.

Don't suspect it was a dead short as the fuses on both the 30 amp and 40 amp wire never blew. The wire only burned in the boot which was a couple of inches at most. Was able to trim it back and add a new terminal. When everything was back up and running the voltage was stable at 14.1 volts with no variance at idle.

Wasn't exactly intermittent. There were times on long runs where it was out unknown to the rider.  The issue had been present for a while.  Hard to say what the cause was. It I didn't see signs of a short to ground.

[nobleswood]

For the feeble minded who have difficultly placing this ring terminal, any chance of a picture ?

 

[twowings]

I'm no expert, but is it possible this was caused by someone crimping the wire(s) with less than the full amount of copper filaments, i.e. the wire(s) were the correct size conductor but in stripping off the insulation in preparation for the crimp some of the conductor diameter and current-carrying capability was lost so repeated applications of current slowly wreaked havoc until failure?

Or, should I put the mushrooms down?   

[pauldaytona]

Canuck, no pictures?

[canuck1969]

Canuck, no pictures?

Sorry Paul. The owner took some pictures but I never got a copy.  Hoping he would post them but let me see if I can get a copy.

[canuck1969]

I'm no expert, but is it possible this was caused by someone crimping the wire(s) with less than the full amount of copper filaments, i.e. the wire(s) were the correct size conductor but in stripping off the insulation in preparation for the crimp some of the conductor diameter and current-carrying capability was lost so repeated applications of current slowly wreaked havoc until failure?

Or, should I put the mushrooms down?   

Possible scenario. Since there were two wires in the terminal may be that only one got a full crimp and only partial on another.  Hard to really know as the wires pulled straight out at the same time. If memory serves one of the wires was more burnt than the other as I had to trim out more food wire from the other  one to make them even.

[canuck1969]

OK, finally got some pictures. Now that I can spend some time looking at these, corrosion may still be a suspect. The green powder is a good indication but have no idea why this particular terminal would experience this much corrosion. The rest of the bikes connectors are pristine. May be galvanic corrosion induced by the poor crimp in combination with heat from the increased resistance but pretty sure the terminal is copper also. Hard to say. If you look at the wires, one of them pulled clean out, while the other one tore out from corrosion and or heat so the original crimp is still suspect. The insulation burned clean off the wires in the actual terminal boot (not in picture).Looks like the original heat source was inside the terminal crimp. Draw your own conclusions on this one. Either way, could happen again so keep an eye on things.

When I crimped on the new terminal I shrink tubed it and wrapped it and the wire with rubber splicing tape so moisture will no longer be an issue if that was the original cause but not convinced that was it. Bit or a chicken an egg thing going on. Only time will tell.

[Wayne Orwig]

So there was no 'SHORT'.
It was a bad crimp that got hot?

[canuck1969]

So there was no 'SHORT'.
It was a bad crimp that got hot?

No evidence of a short on the alternator post, rectifier or the actual alternator that I could see.  It looked perfectly fine until we pulled on the wires and pulled them out of the boot that covers the terminal and the first couple of inches of the wire.  All the damage was in the protective boot and terminal.

[Wayne Orwig]

No evidence of a short on the alternator post, rectifier or the actual alternator that I could see.  It looked perfectly fine until we pulled on the wires and pulled them out of the boot that covers the terminal and the first couple of inches of the wire.  All the damage was in the protective boot and terminal.

People calling a loose connection a short, is a pet peeve of mine. 

[canuck1969]

People calling a loose connection a short, is a pet peeve of mine. 

Mine too....did I say short...........cra p your right in the title.  My bad.

Although I did say "Possible"....

[lti_57]

People calling a loose connection a short, is a pet peeve of mine. 

Yep same here in my Business.  This audio cable has a short. generally its an open.
all good info thanks

[lucian]

I don't think this is from a bad crimp but from corrosion .  We see this commonly on marine engines, especially strand  battery cables.  Moisture is to blame and a little salt doesn't help.   .  Once the corrosion starts the current is drawn through ever fewer strands of the cable and so the compromised section heats up. The fuses rarely blow as there is no  short. Instead you just get localized heating at the reduced section and the rest of the cable and whatever it's connected to becomes a heat sink.     The key is to keep the electrolyte out of the cable by using marine connectors and sealing the cable ends with liquid electrical tape or similar, after crimping .   rust never sleeps

[Kiwi_Roy]

Great troubleshooting, Im not sure it was just corrosion possible a combination of loose connection and electrolysis.
Whatever it was you made a great save and an excellent report

I like to dip the ends of my wires in Vaseline when I'm making a crimp in a wet area, it seems to stave off corrosion.

[canuck1969]

Great troubleshooting, Im not sure it was just corrosion possible a combination of loose connection and electrolysis.
Whatever it was you made a great save and an excellent report

I like to dip the ends of my wires in Vaseline when I'm making a crimp in a wet area, it seems to stave off corrosion.

Fully agreed. when I crimped the terminal back on I used shrink tube and double wrapped the wire and terminal with electrical rubber splice tape and then forced the rubber boot over that. Hopefully that will stop and moisture from getting in but seems like the last place moisture would get it. It is pretty protected under the tank but it is possible. All the other connectors including the exiciter plug directly below it where pristine. No sign of any corrosion from water. Strange one indeed.

Someone on the other forum just posted that his buddy had the exact same problem on his 09 Stelvio so not a one off but nowhere near an epidemic. Either way. Something to keep an eye on. I checked my 2012 by just measuring the resistances I posted and seems to be ok.

[leafman60]

Living with a Moto Guzzi ....

Thanks for the notice.  This doesn't seem to be as epidemic a problem as other Guzzi problems but it's certainly worth checking. I'll soon take a look at mine.  The same is true of other big ring terminal, e.g. the starter and solenoid area.

 

[canuck1969]

Had to tidy up some wiring from my cruise control install so took my tank off today to take a look.

Everything looked good from the outside. Went to pull the boot back and the terminal spun on the post. A few choice words came out of my mouth as I though it had ripped out but turns out the nut holding the terminal on the post was loose. Finger tight at best. That's not good.....

Pulled everything off the terminal (had shrink tube on the terminal and wire) and the crimp looks good. Wires didn't seem loose in the crimp but re crimped it just in case.

Wrapped the exposed parts in rubber splicing tape and made sure the nut was on tight. It is a Nylock nut but still worked its way loose over time.

Started the bike up and for once in a long time I had 14.1 V at the dash and 14.3 at the battery. I had been running 13.9 at best for the last year or so. I assumed it was all the extra electrics I had put on, but nope, it was the loose nut.

The one thing I did notice is that there was no sign of corrosion what so ever. This is a 2012 with 55,000 km on it. The one at the beginning of this thread was a 2013 with 15,000 km that was bought later as a demo that had only 700km (not sure of the year it was bought).

I still don't think the 2013 was caused by just corrosion. I would have expected to see something on mine.