Protecting ECU

[Admin Jaap]

On the Dutch Guzzi forum I came across this link. http://paaat.guzz.free.fr/diode_transil/english.html

I don't know if this subject was covered already, but what are your opinions on it?

[Guest vkerrigan]

I was under the impression that the older Sports (pre 02) required something like this but the situation was remedied on all 02 and later machines. I'm sure Carl A would know for sure...........vk

[zebulon]

It is vital for Sport ie / corsa - centauro & daytona rs.

it seems also good for V11 2000.

Not seems necessary for the newest ones.

But regarding the low cost of the installation it could be done without trouble.

 

For sure they was big troubles with bike from 1996 to 1999.

when the battery died while you are riding you just burn the ECU and you must replace the complete unit (800 EU the unit !).

 

It has been designed with friend and save a few units.

We tarted to work on this when 3 of us has burned the ecu and decided we must found an issue.

[TX REDNECK (R.I.P.)]

You can do a search ( transil diode)on the COG forum for information overload

[Guest Nogbad]

Is this a recommended mod? What is the likelihood of blowing up the ECU as a secondary effect of a battery or alternator/rectifier/regulator fault?

[callison]

Well, I'll throw in my 2 cents worth - which is exactly what it's worth since it's based on observation and not hard fact/science.

 

First, the less hard data:

The WM16 (Sport 1100i/Daytona RS/Centauro) ECU has a zener voltage regulator on the 12V input to the box (known). This zener shorts to ground when overvoltaged (known) and - apparently - saves the ECU from further damage (probable, with a fair quantity of the boxes repaired by replacing the zener. Dealer diagnosis would simply say it's dead and a full replacement in order (also known - and hideously expensive).

 

The WM15 (V11 Sports et all) apparently "crowbars" when overvoltaged and blows the protective fuse (my observation, but not confirmed - yet). A much better approach.

 

With those two observations out of the way, let's consider the transil diode protective mechanism. In the presence of an overvoltage, it conducts to ground - and blows the fuse, thereby protecting the ECU. I don't know whether the transil diode "recovers" from this action or has to replaced. Never looked into it. Maybe the WM15 uses an transil diode internally or maybe some other semiconductor device that operates in a similar fashion. In either case, the fuse blows and not the electronics downstream.

 

So why is it that the WM16 bikes seem to have a need for this protection? The transil diode has also been installed on older bikes that have the P8. Was it necessary for the P8's? I don't know. I do not recall ever reading about a P8 that had a problem, but if I owned a Guzzi and I heard about a series of ECU failures (WM16's), it might seem a logical choice to protect my P8. Nothing wrong with that. It's a good choice.

 

So... we're back to the WM16 as installed on the early spine frames. I suspect the problem never occurred on a Centauro because the voltage regulator is mounted directly to the frame somewhere (never looked - does this mean I have to buy a Centauro? ). The Daytona RS and Sport 1100i's are different. On THOSE bikes, the voltage regulator is mounted on the fairing sub-frame and the ground return (and reference) is based on the uninhibited continuity of the electrical path to ground THROUGH the mounting bolts for the fairing sub-frame. NOT a good choice. Initially, there is no problem, but as time passes, corrosion builds up on the bolts, or the bolts become loose due to mechanical action - and the desired good ground path - becomes one of resistance and changes the dynamics of the electrical system. When the path becomes resistive enough, the reference the regulator needs to the actual frame is changed with a resultant over-voltage to the system (ECU) with the result that the WM16 "eats" its zener and/or the tach burns out etc. Small wonder Guzzi EFI bike owners scurried towards any plausible solution to the problem - the transil diode. Not a thing wrong with that as a safety mechanism and I applaud the engineering approach applied by the originator of the solution. It really is a good one. But... it doesn't address the fundamental problem, which is the voltage regulator ground path for those specific models of Guzzi's. All it really takes to ensure the proper operation of the regulator is that it be referenced properly to the engine block/chassis with a suitably large gauge independent ground lead between the case of the regulator and the engine block. This will do wonders for making everything behave. Since the ground wiring in the instrument harness on these bikes is also under-gauge and a bit flaky, it does wonders for the instrument panel to add a small gauge ground wire to the back of the tach and speedometer and route that down to the newly added heavy gauge ground on the regulator. NOTE: This really only applies to the Sport 1100's and Daytona RS's. I'm less certain that it would apply to the earlier carb Sport 1100's, but it may. It certainly does not apply to any other Guzzi that I'm aware of. I've been harping this solution since 1999. That give's you an idea of how long it's been persisting and why it pops up at seemingly interminable intervals. As the bikes accrue miles or weathering, the ground path deteriorates and the system goes bad. I had a LOT of miles on my bike in the first 18 months I had it, and so did a few others. We just experienced the failure earlier because of it and that's all. As the other bikes in the fold get up in years/miles, they're experiencing the failures too.

 

And so, on to a specific WM15 on a V11 Sport. Mine. This is covered elsewhere on this forum on a rather extensive thread, but the short story is: my fuse blows when the engine is revved rapidly. Otherwise, it behaves quite normally. The ONLY thing that has changed for the wiring on this bike from before the accident and after, is that the frame has been powder coated. No other changes. And powder coat - doesn't make for a good ground point. And a bad ground reference - means an overvoltage that the protective device on the WM15 (if it is like the transil diode) reacts to by blowing the fuse. I'll know better on this when I get my transmission back - again - and get the bike back together. I guess to be thorough, I'd have to put it back together without "improving" the ground and seeing if the fuse still blows under the proper condition (I am not enthusiastic about an "experiment" that could cost me nearly a thousand dollars though) and if the fuse still blew, then apply the improved ground (ground lead plus removal of some powder coat at the regulator mounting plate) and see if the fuse still blows under the same applied conditions. While this is probably the most correct scientific method, I'd rather avoid it and go for the probable corrective action first as that would be the most cost effective in view of the possible damage to the ECU if all that I have stated were incorrect. In specific relation to my bike, the failure mode is probably as stated, but not necessarily so - insufficient hard evidence. Time will tell - no matter what approach is taken, one would just be more informative than the other.

[TX REDNECK (R.I.P.)]

I'd have to put it back together without "improving" the ground and seeing if the fuse still blows under the proper condition (I am not enthusiastic about an "experiment" that could cost me nearly a thousand dollars though)

 

C'mon Carl take one for the team, it's all in the name of science

[DeBenGuzzi]

WAIT now I'm confused which models are most at risk here? should I be doing this protective measure or is it redundant on my bike. (crossedfingers) cause I am no good with electronics I could take apart a motor and put it back as long as someone else did the electronics for me, Maybe more that no one has showed me how to do it right and I'd had my fun with it and my RC hobby blown out a cervo or two. I'd RATHER not blow out an ECU!

[callison]

WAIT now I'm confused which models are most at risk here? should I be doing this protective measure or is it redundant on my bike. (crossedfingers) cause I am no good with electronics I could take apart a motor and put it back as long as someone else did the electronics for me, Maybe more that no one has showed me how to do it right and I'd had my fun with it and my RC hobby blown out a cervo or two. I'd RATHER not blow out an ECU!

43879[/snapback]

 

At risk:

The WM16 (Sport 1100i/Daytona RS/Centauro) ECU has a zener voltage regulator on the 12V input to the box (known). This zener shorts to ground when overvoltaged (known) and - apparently - saves the ECU from further damage (probable, with a fair quantity of the boxes repaired by replacing the zener. Dealer diagnosis would simply say it's dead and a full replacement in order (also known - and hideously expensive).

 

Not at risk (probably):

The WM15 (V11 Sports et all) apparently "crowbars" when overvoltaged and blows the protective fuse (my observation, but not confirmed - yet). A much better approach.

[Guest Nogbad]

Thanks Callison. Bit more than 2 cents worth, and very informative. I shall simply make sure I keep my ground connections clean and tight. Thanks for the comprehensive opinion.

[luhbo]

...While this is probably the most correct scientific method, I'd rather avoid it and go for the probable corrective action first as that would be the most cost effective in view of the possible damage to the ECU if all that I have stated were incorrect...

 

43833[/snapback]

 

One could also suggest to visit the next car repair shop and to connect the V11 to their diagnostic system. Normaly every half way state of the art shop nowadays owns such an oscilloscope and so should be able to logg these killer-spikes on your harness.

In my non electrix expert eyes it seems to be abit risky to try to protect electronics with the help of fuses, especially car type ones. They are so lazy. I remember to have already ruined the harness of my LM3 cockpit before the fuse finally blew.

 

Hubert

[stormsedge]

If I read this right, then I am (probably) okay to put a trickle charger (with storage mode) on the system without disconnecting the battery from the system? Would make it much easier during the cold months. k

[jrt]

It's the large overvoltages that kill the ECU- 'spikes'. As long as you don't drag the charger leads over the battery and arc it out, then you should be ok. Same with jumping the bike (and that's how the ECU's were ususally blown). Putting one of these on your bike is completely analagous to putting a surge protector on your computer.

Re: The charging system- When just running the bike, it should definitely not be putting out lots of hash, spikes or elsewise.

Re: fuses- yes they are very slow. An electrical spike can last a few thousanth's of a second (or less) and that's plenty to damage sensitive equipment. A fuse takes hundreds of thousanth's of a second to blow. A transil diode takes a few millionths of second to kick in- much faster- thus saving critical stuff downfield.

You can put a protective circuit in you bike- won't hurt it a bit. Or you can leave it out and trust the engineers to have taken care of it.

All that said, I've thought about making one for my bike- just for fun really. Let me look into the costs and maybe we can do a group buy.

As always, my advice is worth what you paid for it.

[dlaing]

If I read this right, then I am (probably) okay to put a trickle charger (with storage mode) on the system without disconnecting the battery from the system?  Would make it much easier during the cold months.  k

44546[/snapback]

I would not turn the igition key on while it is charging from a trickle charger, or any external charger.

"Spikes kill"

--Buffy the vampire slayer

or was that "Spike kills"?