Breva 1100 ECU disconnected

[Kiwi_Roy]

I think before I blew another fuse I would unplug the ECU then if the fuse pops again you have narrowed it down to the wiring.

The way I approach a short is to replace the fuse with a headlight bulb with a couple of wires soldered on, this will supply the circuit without the lamp getting hot but if you have a short it will glow at full brightness. Wiggle stuff around hoping to create or lift a short signified by the lamp flashing, it's very visual and you soon narrow it down to the part of the circuit at fault, no fuses are harmed in the process.

I would leave the ECU unplugged at this stage assuming it still blew the fuse with it unplugged, no sense in putting it at further risk
If the ECU is blowing fuses you have a serious problem

http://www.thisoldtractor.com/guzzi007/schematics/2005_Breva_1100.gif

Sorry I'm off for a week, have it fixed before I get back 

[beetle]

First thing I would do is disconnect the speedo sensor.

[pauldaytona]

I think ecu has no power. So try connecting guzzidiag and see if that can connect to the ecu. That goes outside the can line, so the dash doesn't play a role in this.

[tris]

I sort of tried that yesterday Beetle before I worked out that it had blown the fuse again so couldn't

I'm feeling flush so I'll unplug the speedo sensor and stuff a new fuse in - you never know I might be lucky 


Paul, I did that and GD wouldn't connect


I think the confusing thing is that the ECU has 2 power supplies, one via the 3A Fuse E to ECU body connector pin 4 and one via the 15A Fuse D to body connector pin 17

So even if Fuse E is good, loosing Fuse D makes it look like a power less/disconnected ECU

[pat80flh]

One wire is probably battery/keep alive voltage, and the other ignition power.  I'd assume both need power for the ECU to work.

You don't have a relay full water do you? 

[pauldaytona]

If you pull the little connector at the starter engine back, see if the fuse still blows when you push the starter button. My 08 does not need the startus interuptus mods. Still running on original battery.   There was a mod to the first series that you had to take a relay out, what is you VIN?

[tris]

It's an 06 bike if that helps I don't have the VIN to hand just now

I've had non bike stuff to do over the weekend so will get back on it next week

[pauldaytona]

It's an 06 bike if that helps I don't have the VIN to hand just now

I've had non bike stuff to do over the weekend so will get back on it next week

 Sorry my fault, that was with the 2008 stelvio.

[tris]

I think I've found the cause - wheel sensor





The housing has bleb on the end that I assume it wasn't made with



Plus a crack around the moulded in boot.

Also I can't get any sensible values out of the sensor so I'm guessing is BER

However, can someone (Roy perhaps) please just check my rationale as to why I think I had the failure I had

1) Assume that the Speed Sensor body is full of water and shorting live and earth
2) Pushing the starter button pulls the main Injection Relay In
3) Juice via fuse D flows through this relay and straight to earth blowing the 15A fuse D due to the short in the speed sensor
4) This kills the second live feed to the dash
5) So dash lights up and does its test stuff via the 3A fuse E but goes dark and only shows the red triangle/ECU disconnected because it has no power via Fuse D. red triange being powered by the 3A fuse

Does that sound sensible?

[Chuck in Indiana]

Sounds reasonable to me.. can you just unhook it?

[pat80flh]

Sounds right. Disconnecting the sensor at the other end should remove the short, so fuse does not blow, bike start and run?  ... maybe with a speed sensor code.

[Kiwi_Roy]

I doubt the Wheel speed sensor has anything to do with the ECU but being a Guzzi anything's possible.

Actually you may be right

In fact I'm certain

Who would of thought a wheel speed sensor would take out the motor but there you go fed from the common red/black wire, also bought on by the wet conditions that you rode through.

Those sensors on the Breva have history, where the soft wire comes out of the hard plastic it creates a wick point for moisture, sucks right in to the solder joints sits in there festering away.
When you replace the sensor apply a little silicone to where the wire comes out, this sticks to the plastic and the wire creating a flexible waterproof seal.

I told you to get it fixed before I got back LOL

[beetle]

Did I not say it was the sensor?

[Kiwi_Roy]

Yes you did, I guess you've seen it before as well.
 
Its a common problem with flexible cables going into a molded electrical device.
It's a poor design that can be fixed with a dab of silicone.

Might have lasted for years if it hadn't been ridden in the rain.

[beetle]

It's a known (but uncommon) issue with the early rear sensors on CARC bikes. The newer sensors seem more hardy.

[Moto]

Did I not say it was the sensor?

Yes, but I suggested unplugging it first, on page 1.

But who's counting?

Tris, congratulations on persisting and getting her done.

Moto

[Kiwi_Roy]

Yes, but I suggested unplugging it first, on page 1.

But who's counting?

Tris, congratulations on persisting and getting her done.

Moto

So you did, reply 28
Moto gets the cookie

[tris]

Thanks everyone

The speed sensor was high on my suspect list because of earlier issues I had had that had "gone away" so Motos & Beetles comments helped me to focus, but i struggled to see how a speed sensor  could kill the bike

However, I was keen to see a cause that linked to the result and the crack letting water in obviously does.

The thing that threw me for a bit was that it blew a fuse and then it didn't and the only explanation I could come up with that it had dried out so I went looking for a crack.

It took me half an hour with a bright light to finally spot that crack!

So, a new sensor is going to be sourced and I have a cunning plan that doesn't include my giving Piaggio one hundred and sixteen of my hard earned pounds 

As I have a Mech E background this sparky stuff takes me a while to get my head around, however to para-phase Roys sig

Moto Guzzi - providing learning opportunities for 90 years

I now know about stuff I didn't know a week ago ..... which is nice!

[Bisbonian]

The speedo sensor was a problem on the earlier Grisos but was never a big deal on the Breva/1200S/Norge.

The Griso sensor was mounted in the rear swingarm and evidently caught a bunch of crud and water, the sensor was eventually changed and sealed.

I'm not saying the speedo sensor isn't your problem, it just wasn't the big deal on the bikes that had it on the front fork that it was on the Griso.

[tris]

You could well be right Bis so while the dash is with Carmo to sort the LCD I plan to break and remake every connection I can and give everything else a good coat of looking at 

[Chuck in Indiana]

You could well be right Bis so while the dash is with Carmo to sort the LCD I plan to break and remake every connection I can and give everything else a good coat of looking at 

As far as I'm concerned.. that is a good plan for *every* Guzzi. Most on road "break downs" can be cured by a preemptive strike.
I didn't bother to find out which circuit was ready to fail.. but the guy that "don't fix nothing until it breaks" would have found out shortly. <shrug>
2017-03-15_04-09-48 by Charles Stottlemyer, on Flickr