750 Breva Mysterious electrical failure

[rossw]

On Friday on my way home from work, my 750 Breva suddenly stopped as I was approaching a roundabout. By "stopped" I mean completely, as if someone suddenly disconnected the battery.

I immediately turned off the ignition and turned it on again. the dashboard lights were back up, so I was able to restart the engine and all was well. the I noticed that the clock and trip meter had reset themselves, and for the next couple of days there was more vibration than usual. That has smoothed out since, and the problem hasn't reoccurred. I suspect the vibration was caused by the ECU starting from default settings and some ignition and fueling "relearning" took place over that time.

I checked both battery cables and they are tight and clean.

What else could cause a sudden and total temporary loss of power like that - to the extent that everything resets?

 

[john zibell]

If everything hadn't reset, I'd suspect the side stand switch, but since you had the reset other components are suspect. I'd carefully check the fuse holder for the two 30 amp main fuses to start. Since it was an intermittent problem, you may need to wiggle some wires, even go into the fuse holder itself to see if there are any weak points there. Next suspects would be the main injection relay, or even the ignition switch. Carl's schematic may help you to track where you might have caused the power loss https://www.guzzitech.com/guzzi007/schem ... _Breva.gif

 

[Holt]

I'd also check the multipel connectors in the system, (for corroded pins) fx backside of the dash cluster, and - to my mind - the backside of the ECU.
If it's an intermittent failure, it's pure hell to find...

There may be a notice found in the ECU, but I don't think it can be read in a VDST, but maybe the glorius Navigator can?

 

[NOLAGuzzi]

I've had that happen from time to time too. It usually occurs when my battery is low. A dead bike in traffic is not fun.

 

[rossw]

Did it to me again three times this morning. Once it warmed up the problem went away. The first time was still in the garage, so I whipped out the multimeter and started probing around. When I tried to test the earth on one of the relays under the seat, it sprang back to life. I don't know whether it was because of what I did or just spontaneous. Then it died again at the traffic lights a few minutes later, and came to life again without me doing anything. Once it warmed up it was fine.

I have gone over the circuit diagram, and the only place I can see an open circuit causing complete loss of power apart from the battery itself is the holder for the two 30A main fuses. I will be continuing my search there this evening.

By the way it's raining, so water may be playing a role here too.

 

[Holt]

I've had that happen from time to time too. It usually occurs when my battery is low. A dead bike in traffic is not fun.

May very well be the cause!
Ross, how is the battery? As old as the bike?

I have never noticed the failure, tho I still got the original 2003 Yuasa battery - but I've noticed that it will drain quite fast by now, so I'm going to change before the summer joys. Electronic gizmos are quite senistive to voltage fluctuations.

 

[rossw]

I've had that happen from time to time too. It usually occurs when my battery is low. A dead bike in traffic is not fun.

May very well be the cause!
Ross, how is the battery? As old as the bike?

I have never noticed the failure, tho I still got the original 2003 Yuasa battery - but I've noticed that it will drain quite fast by now, so I'm going to change before the summer joys. Electronic gizmos are quite senistive to voltage fluctuations.

You're right and I checked the battery, although the battery was a new one when I bought the bike in May, there might have been a charging problem (there wasn't).

I've found the culprit.



The main fuse had a high resistance joint. The heat melted the surrounding rubber and plastic causing the intermittent contact.

Many thanks to all who responded especially John Zibell for pointing me in the right direction.

The eagle-eyed among you will notice that the fuse holders are not the originals. They are aftermarket automotive high current fuse holders, held in place (sort of) with a zip tie. Can't blame Italian electrics for this one.

Looks like I will be replacing them both on the weekend and finding a better way to mount them. Then I should have no more problems. :roll:

Another piece of non-standardness is nearby.The previous owner or their mechanic has replaced the starter relay with an aftermarket one, and done the starter wiring mod for smallblocks mentioned in Guzziology that increases the current to the starter solenoid. So I've had no starting problems at least.

 

[Mi_ka]

Most probably the original fuse holders melted down too!
It seems the Italians will never come to their minds!
I posted this related post just a few hours ago: https://www.guzzitech.com/forum/188/4842.html#p35563
This was 13 years ago! Nothing has changed!

You go and buy a wonderful bike costing big $ and it all goes down to a CHEAPO FUSE HOLDER! :evil: melting in the middle of nowhere
Guys like me consider this fun and an easy fix (when not messing up an entire trip) but guys not like me just bite the dust.

And then the italian bosses go around scratching their heads why the bikes are considered unreliable!
Just spend half a euro on better fuse holders!
Aaaargh! :evil:

Edit: Am I too harsh and is it just my illusion that such problems persist even on new Italian bikes?

 

[NOLAGuzzi]

:shock:

Hopefully the other "improvements" won't cause you any trouble.

 

[rossw]

:shock:

Hopefully the other "improvements" won't cause you any trouble.

They shouldn't. It's pretty easy to get at and the only really vulnerable part is the connection to the starter solenoid, which is an unprotected crimp type spade connector. I'm going to put some heat shrink on it to protect it from the weather and to hide the bright orange wire. Other than that, it seems these connections were done properly. The change fixes a known issue with 750 Brevas being difficult to start due to typically thin and underspecced Italian wires. (Is copper expensive in Italy?)

Now seeking a good quality high current fuse holder in Australia.

 

[rossw]

Most probably the original fuse holders melted down too!
It seems the Italians will never come to their minds!
I posted this related post just a few hours ago: https://www.guzzitech.com/forum/188/4842.html#p35563
This was 13 years ago! Nothing has changed!

You go and buy a wonderful bike costing big $ and it all goes down to a CHEAPO FUSE HOLDER! :evil: melting in the middle of nowhere
Guys like me consider this fun and an easy fix (when not messing up an entire trip) but guys not like me just bite the dust.

And then the italian bosses go around scratching their heads why the bikes are considered unreliable!
Just spend half a euro on better fuse holders!
Aaaargh! :evil:

Edit: Am I too harsh and is it just my illusion that such problems persist even on new Italian bikes?

One of the items I've added to my toolkit (which is heaps better than you get these days on Japaense bikes. Is that because you need them?) is a small testing light with an alligator clip and a probe.

I've had that same testing light for years, having bought it when I had a Mini (think Joe Lucas, Prince of Darkness :twisted: ). It's not only Italian electrics that die mysteriously in the middle of nowhere in the dark because of cheap components.

 

[Chriso]

My better half had a similar problem. The bike would simply stop. It had instruments, the starter would turn over but it would not start. After some investigation relay number 12 (on the wiring diagram) was intermittant. This relay controls ignition and fuel pump. It can be swapped with logic relay next door. Keep this in your memory bank for other posible electrical failure. :huh: