2012 stelvio headlamp wiring melt down

I was riding home last week on my Stelvio and noticed a burning smell - initially i thought it from the clutch (bugger not the clutch) but then when i got home the smell was quite strong around the headstock, further inspection showed that the connector plugs to the headlamps had started to melt as had parts of the wiring.
The following day I got to take a look. ( By the way my bike is very clean and low mileage so was not expecting this problem)
I found that both the blue (earth) wires from the 3 pin plugs had melted quite a bit as had the connector around the area where the earth goes into the headlamp plug connector.
Further inspection revealed that the bulb holder (white plastic disc) and a little bit of the internal reflective lens had also started to bubble and would have melted had my journey been longer.
I was running Osram night breaker 60/55 watt bulbs and initially thought the bulbs to be at fault but a bit of checking around revealed another Stelvio weakness and compromise.
(My bike had a warranty work for a rewire before i bought it this is documented by Moto Guzzi so i thought any such foibles would have been ironed out. It appears not.
The blue earth wires appear to be 2mm square so should be good for 25 amp - as they share the load between both lamps that draw 5 amps per lamp thats 10 amps going through a cable, obviously there is some drop off due to cable length etc but it appears on paper everything should be fine.

The resistance is centred around the actual connectors but the slightest bit of oxidisation / corrosion etc will cause enough resistance in the circuit to cause overheating, this suggests poor quality connectors that rapidly become oxidised.
I think a protective coating would have been best and I have yet to remove the tank and find where the circuit is earthed onto the chassis - again another point that could well be corroded and thus backing up the flow of electrons. I will be checking as many connectors as i can find while i have it all apart
The other headlamp wiring is also very thin wire (1mm) and even worse has part of the circuit going through the left handlebar switches which again if overheated due to resistance can cause damage therein and become quite costly.

The resistance build up means the headlamps simply cannot work correctly and then start to overload and overheat. (I also noticed the headlamps seemed a bit dim the last few weeks but though that down to road dirt on the lenses).
I am currently in the process of replacing all the contacts in the headlamp circuit and running in another higher grade earth circuit bolstering the wiring by an upgrade in the earth wiring size.
I think maybe some electrical grease on the contacts is well worth adding - but more importantly check the contacts if they have gone dull grey it may be worth replacing them before resistance can build up and you have the same issue.

This was a common problem on Nissan Micra cars and is also a known problem on Triumph speed triples so not just Guzzi - but is mainly down to a compromise on quality materials. The bean counters at play again.

Further inspection under the tank - I find two multi block connectors on the left side behind the coil, and two next to the abs unit these connectors are not sealed waterproof connectors (coming from the switchgear on the handlebars) and in the flow of air /rain and road muck - both have a fair amount of corrosion on the pins inside not directly releated to the headlamps but a problem developing for the future no doubt.

I have taken the pins out and cleaned them - then lubricated them with acf 50 and sealed the ends of the connectors with electrical waterproof grease . Luckily the whole headlamp assembly and wiring come off in one neat set up so repairing and doing the wiring here is really quite easy to do, I worked my way along the various connectors cleaned and used protector on them.

I note both the coil pack earth connectors are similar to the headlamp and of very poor quality and very oxidised. I am about to replace these with brass fittings. I have some way to go to get to all the various connectors etc but once the tank and fairing are removed everything was very easy to get to.

Still love the bike its brilliant, but like every guzzi I am sure they build in these foibles to keep owners busy.





Just seen this, not sure why you have deleted those posts? There was a problem with the starter motor relay in the front fairing, there were two. The nice man at Newcombe Bros took one out as apparently a failure caused the starter motor to turn when the engine was running and burning out the starter motor. My bike is 2010 model. Leaving a multi pin connector open to the elements I eased on a piece of bicycle inner tube over the socket folded it over then added a tie wrap to keep the weather out. I wonder if your bike still has two starter motor relays?

Hi Chris thanks for the reply, I still have two relays - i will have to look at which one can be taken out, but thanks for the pointer.

I deleted the other bits above because I had gone a bit off topic and was going on about remodelling the Stelvio into something lighter and more like the 850 tt.
I had added pics of a Dakar bike I had built in the past. (BMW airhead based on an HPN racer) It was a big job with reworked chassis, engine suspension and almost every other component remodelled, improved and strengthened, bit of a one off, it took me almost a year to complete.

Anyway i will look at the various options for the relays. Unless you are aware even by the colour code of the wiring which one was removed and has it had any other effect. Cheers Jake.


Mine is a 2010 model with the plastic fake tank containing a glove box (Italians eh?) The one removed was the front one of the pair of relays to the right of the headstock down tucked within the fairing, it has two purple wires, one yellow wire and one yellow/red wire,

I have looked at Carl Allison’s wiring diagram for 2008 Stelvio and it is not like mine. I think the nice man at Newcombe Bros in Chelmsford may have said start up relay not starter relay, but even these show no purple wires, but they do have yellow and yellow/red wires on the diagram.

Apparently it was a fault that was sorted under warranty during a service between mid 2011 and early 2012. I have had no issues with it apart from click no start that is either resolved by rocking the bike in gear or cleaning the batter terminals if the former does not resolve it.

Peter Newcombe is the bloke who did it, if you would like their number let me know.

Best wishes Chris

Chris thanks very much for you information, mine is a 2012 model and it has both a start up relay and a start up maintenance relay but none of the wire colour combinations match those you give. I am assuming they may well have sorted the issue on later models.

It is a very complex wiring set up its a shame they couldn’t simply keep it more basic. This is what happens though once they start adding in to many automatic features and sensors. I can never figure out why they just didn’t fit a on off switch for the light. much easier.

once again thanks very much. I have rewired the front lights added in some extra heavy earth direct to the frame as well as cleaned and then used conductive silicone grease on all the connections.

Im hoping this will solve the issue i have had.

Very best regards Jake.

Can’t recommend ACF-50 enough to help prevent corrosion issues.
Safe for all Electrical components and connection/plugs etc.
Not cheap, but it works wonders, and a little goes a long way.

Tell me more about the Relay removal, are you saying there’s one fitted that’s not needed?
Had an issue on my '09 a few months back with the two main Relays, sockets were corroded.
I replaced them, spliced new ones in.

I also re-wired the Headlights soon after I bought it (Sep '15), so both High-Beams work.
Fitted an extra (4-way) Fuse Box, for the Headlights, LED Spots (ditched the horrible Hella Fogs), Horns, and Charging Socket.