MV Agusta Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
Hello all,

I was riding my Brutale yesterday first time at night and I found a strange and concerning behavior of the headlight.

Every time I accelerated a little faster the headlight would switch off or dim (I can't exactly tell).
I have searched the forum for similar issues but I haven't found anything related.

Did anyone have similar issues and could help me?

Thanks!
 

·
Registered
Joined
·
96 Posts
Maybe an alternator or rectifier/regulator issue? Alternator's really the only component in the electrical system that has variable output based on rpm. Voltage regulators go very frequently on motorcycles, often due to heat and just normal use. The tell-tale sign of a bad reg/rect is dim or intermittent lights, so prob first thing you should check. Check both though, but I'm not certain how on our bikes. Regulators are typically deck of bridge cards-sized ally things bolted to the frame somewhere, but I have no idea where ours is, or if it might even be built-in to the alternator or FI system. The manual references it, but doesn't picture it. Sometimes I miss old-ass bikes!
 

·
Super Moderator
Joined
·
22,071 Posts
I doubt it's the alternator and or regulator, your bike wouldn't be running for long if that was faulty.
If the rest of your lighting stays on while the headlight goes out then it's either a bad connection on the bulb, or you have a SPU problem.
I'd check connections both ways.
PS. Rectifier is on the alternator, and when that doesn't work a light on your dash comes on signalling battery problem.
 

·
Administrator
Joined
·
19,833 Posts
I discovered my index finger was resting on the "flash-to-pass" button and I would inadvertently depress the switch when I really twisted the throttle hard.......

I will bet your finger touching that button is the cause...and you will never figure it out until you pay close attention to where your hand/finger are when you whack that throttle on hard.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #5 (Edited)
Thank you all for your advice!
Since I don't get the low battery warning I doubt that it could be my alternator. I also always plug the battery in after riding and it always is completely charged.
I will check the SPU version and I will also try to pay attention to what my left hand is doing :brutale:
I hope that it's just my nervous left finger ;-)
 

·
Registered
Joined
·
48 Posts
It took months for me to find the headlight issue on mine so I hope this may be the "light" you need. As many have found out, virtually everything on the bike through the ecu. The result it that issues in normally unrelated systems can affect others unexpectedly and certainly not in what most would consider the normal diagnostic path.

When mine reached certain rpm/speeds the headlight would go out. Happened at night accelerating accelerating past 85mph entering into a 100degree left on the edge of town (unlit road, almost killed me).:lightning

THE PROBLEM
In my case found there was a short in the wiring harness as is goes into the switch housing to the signal switch. The wires are smashed together pretty tight and I happened to find ONE bare strand on ONE wire that goes into the blinker switch. Normally an unrelated system in regards to a headlight issue.

I stress, ONLY one strand on one wire could barely be seen though it was evident that that particular wire and another couple were being smashed flat. As I manipulated the wires, more strands revealed themselves. I did not chase down the half dozen possible shorts that could have been created. ...Several months of frustration spurred me to simply eliminate any chance that what I found could create an issue of any type.

THE FIX
I unsoldered the wire from the switch, put on a piece of heat shrink, resoldered the conductor to the switch, cleaned with flux remover (cools it down and cleans it, ...91% rubbing alcohol works) and after closely inspecting each and every wire at that location (where it enters the switch housing). I carefully realigned all the wires to reduce the compressive force exerted when buttoned up. ...Avoid any potential problems, do not reassemble the housing if there is any heat left in the wire(s)!

The issue was totally resolved.:highclap:

I must stress that it took opening the switch a number of times and actually removing the turn signal switch from the housing to spot the single strand that was BARELY visible once I started separating the wires. Had I not separated the wires I would not have spotted it. :ahhh:

I had looked at least six times over 3 months or so and was almost ready to strip the bike and make a track bike, ...or see how far it would fly :conveyer:

I've been chasing electrons for over 50 years and have rarely run into such a challenging cross system issue in such a simple electrical system. It's scary.

Normally very reliable, these bike are truly amazing bikes and worth every effort if you have the time to go through thing methodically.
Every once in a while I get the notion to redesign the wiring and electronics :bash:, I twist the throttle a bit more. Cures that.:f4:

Let me know what you find.

Happy trails
 

·
Registered
Joined
·
48 Posts
BTW ...esq'z me is on point as well. I had the headlight dim a number of times as well and it ended up being my finger inadvertently hitting the button.
Kinda like wondering why your bike won't start and then noticing it's not in neutral or the kickstand is down. I know that never happens to me :banghead:
 

·
Super Moderator
Joined
·
22,332 Posts
Damn, and here I was thinking that maybe you simply surpassed the speed of light momentarily.....
 

·
Registered
Joined
·
666 Posts
glad you got it right . by any chance did you take pictures? is this a build related problem or someone else was in there before you? thx
 

·
Registered
Joined
·
48 Posts
It was a build issue on a bike occurring around 1500 miles. A little more care during assembly would have prevented them being smashed. Late night when I found it so no px. All you'd see now is a piece of heat shrink a wire...

And yes, momentarily attaining warp speed has been an issue. I was in orbit long enough that they promoted me from space cadet to Admiral :later:
 

·
Registered
Joined
·
4 Posts
Discussion Starter #12
Hello all,

please excuse for me not replying such a long time but I was very busy with remodelling a whole house.

The only thing I could test and already exclude is my finger from unintendedly hitting the high beam button. I will use the winter time to perform a deeper analysis though.

I noticed that my battery wouldn't hold its charge for any longer than a few days, could that be the issue? From my understanding that wouldn't make sense since the generator provides even more power at high rpm or am I wrong?
 

·
Registered
Joined
·
68 Posts
I had a VERY similar headlight issue... It turned out to be a loose connection at the batteries negative post. Tightened things up and that's all it took (at least THAT time).

Check the basics first, a lot of electrical troubles stem for bad grounding.
 
1 - 13 of 13 Posts
Top