Modern Vespa

This is one of those situations where you need to seriously think about undoing the mods and going back to stock.

That is the strangest part, neither the computer nor the reverse were touched in any way, none of those circuits and/or mechanical parts were touched.

Not familiar with this specific system
What are the possible reasons the calibration can't complete?
Are there limit switches, could one be broken, disconnected...
If there is position sensor the span could be out of range

What battery have you got in the scoot, I know that 13V is best to have otherwise can cause complications sometimes, have you tried with a different battery

The reverse system have a solenoid with a potentiometer that says the ECU the solenoid position. Both come as a unit. I purchase it but continue the same problem

I do a test changing the battery for another (in the very first iteration with this problem), same result.
I have a Noco Lithium and voltage is consistently above 13.2v and when the engine is on what the alternator send (always in correct levels)

I see 2 possible outcomes to this dilemma.

1). Transport the bike to a neighbouring country at moderate expense that has a official dealer and the PADS diagnostic system

OR

2). Cut your losses financially and send the bike to the scrapyard and consider it lesson learned aka "if it ain't broke don't fix it"

Or if the scoot is rideable forwards, take it out for a ride and see if something settles down, I have seen stranger things with bikes and ECU,s

The MP3 is 100% rideable forwards, all except the reverse works flawless

In that case, live with it. Reverse is an unnecessary complication for a scoot

Could the reverse switch be faulty ?

True I bought mine for the reverse gear, and still have not used it except to test for this thread

Check with two and connecting direct, same situation

Before this happens I use it 4-5 times, it is quite comfortable/useful in certain situations, especially if you need to move that weight in a confined space and with some inclination.

I like things to work as they should, if it has it, it should work. Maybe if I can't make it work the way it is designed, I will have to go to plan B, after exhausting the resources in Plan A (make it work as designed).

Plan B is to make the D/R switch a safety circuit (the only thing I haven't been able to figure out is how to disable the accelerator) and that by turning R the reverse can be activated with a separate button, probably placed on the central dashboard, where is the button to open the seat, that there is space for that and it is not something that is non-reversible

LOL. On a Italian vehicle? Not a chance in hell.

The Italians may have invented electricity, but they mastered the art of electrical malfunction.

Try finding a Maserati owner who can say with confidence "everything works".

Well funny today I spoke to a friend in Paris, who had a problem with reverse, and he told me that Piaggio replaced this faulty relay, that seems to test ok, but is not, relay replaced with part below, and reverse was fixed.

https://www.sip-scootershop.com/de/product/relais-piaggio-12v-30-10a_PI016360



https://ibb.co/GMkPy6x

Also check out this video in That shows a piece that does not work correctly and is stopping reverse from working.

This is excellent information, thank you very much. A relay is a lower cost to do a test. We tested all the relays (the 2 brown ones near the seat and the black one on the dashboard, the black is the one your friend speak about) and they all seemed to work fine, but your friend says that the relay test was ok but was it still bad? I'm understand correctly?

Could you ask him, if it's not too much trouble, what were the symptoms that the motorcycle had when it had problems? For example, if putting the D/R switch in R didn't do anything (the beep didn't sound, etc.)

Appreciate a lot your help in solve my dilemma

Seeing the manual reference, in mine workshop manual says is the other one (so maybe I change both je je je).

He simply told me everything seemed to be normal but scoot would not reverse so took it to Piaggio and they gave him the faulty part to see, and replaced it, now his scoot reverses fine, most of my friends in Paris have Mp3,s

See picture below also

This are the brown ones I say in previous post

Yes it was only for others to see also what they look like, and if it ends up it is not the relays, it can only be the part in the video that I posted that is not engaging correctly.

I speak with the person that do the video you posted. He has another one (I think the correct sequence is this and after the one you posted) that shows better the symptoms (again for others). Is more a mechanical problem where the solenoid activate but the reverse don't engage.

Here the video: https://youtube.com/shorts/gnRdHnLjbeQ?si=t57miLH0IUs41WGJ

Well hoping the solutions are either in the video or the relays, otherwise I have no other ideas, really hope something works.

I try to check the relay mater tonight, all finger crossed

Sad Update

Today I was finally able to do the pending tests:
1. Replace the relays on the front (although all of them had already been checked, but following the comment of flybynight about his friend from France). Result: problem remains the same
2. Check if by putting a supplement (a small piece of cardboard to force the potentiometer and solenoid to be fully closed) on the solenoid vs the part that pushes the reverse engage motor, the potentiometer does give the values ​​that the ECU likes. Result: problem remains the same

After each test I scanned the bike and the errors remain the same. In both cases, if I run the procedure to calibrate the solenoid, it does everything (activates solenoid, activates the reverse motor, etc.), but when finished it says that the calibration was failed.

I can't figure out which cable to try, or what to do. I can only think of going to Plan B, with all the pain in my soul, since it is partly changing the way things act naturally.

It seems that the only thing left in the equation to change/test is the ECU. But how can I do it? What guarantee do I have that it is the problem? Furthermore, from what I have been able to see when changing the ECU it is not just putting it in and programming the keys, but in the case of MP3s I have heard (I am not 100% sure, but I saw a comment in a Robot video) that the new ECU has to be synchronized with the tilt lock computer, which I don't have the slightest idea of ​​how it could be done.

Plan B: use one of the empty button spaces in the central part of the bike (to make it look original), and put a reverse button there, but use the D/R switch to enable the circuit for more security. The two things I don't like about doing it like this are:
1. If by mistake the moment the reverse is activated the throttle is moved, I don't know what damage could happen (and I don't know how to disable the throttle).
2. Placing the button in the central part instead of using the same starter button means that you cannot keep both hands on the steering wheel, which in a reverse maneuver could even be dangerous.

As always, comments are welcome.

I highly doubt this is a ECU problem

Why? If it wasn't broken or at least suspect before this debacle, then it isn't now.

Ditch your Plan B for all the reasons you listed.

It's time for plan C, which is nothing than to just live with the bike as is. The reverse function adds nothing or very little at best to a scoot, bordering on useless feature.

IF this was a 400+ kg Honda Gold Wing or BMW K1600 then yes I'd definitely want reverse too. Not the case here.

The bike in its current condition performs the main 3 functions it needs to do which are move (forward), stop and turn. The only thing left to do is put your mind at rest and close the case. It is what it is.

Some images of relays from French Mp3 forum, showing position and wrapped to protect from weather because they are sensitive to water.

I check all of them, and change the 3 (yes 3 not 2 as expected) at right side (seeing from front to back) and no result. Some interesting is that mine, as I say in other posts before is a Frankenstein (US version ) that merge the 2021 from EU and the 2019, so it have 3 relays in that position. But all checked, tested and changed for new ones in case.

And last thing I found out was some relays needed to be calibrated with Piaggio software, others where just plug and play, very strange, also another guy said a change of weights made his reverse to stop, my head is aching so many possibilities.

WOW that's more crazy that I expect. First time in my life I hear about "relay calibration". About weight, imagine, if you ride alone all is fine but with passenger don't work ha ha ha... don't know what to think right now.

Where are you finding this information? Maybe an extra set of eyes will see something that escaped at first glance?

See below needs to translate as all is in French, but France has most Mp3,s in the world specially Paris, to see pictures you need to signup.

http://www.mp3lt.fr/mp3-500-hpe/107295-probleme-marche-arriere?start=0

My last throw of the dice would be, something is not tightened up or not fitted properly shaft etc in reverse assembly

That was my initial idea, but the fact that the calibration process occurs (even if it ends with an error), turns on the reverse motor, activates the solenoid and moves the wheel backward is what makes me think that there is something else that I am not seeing or understanding 😟

What about if the reverse is going into security mode, it does that when you reverse uphill to far, shuts you out for 30 minutes or so, also you say wheel goes backwards, is that on centerstand, if so when you put weight on wheel it stops, if I understand correctly, which can only mean something is not grabbing correctly a spline or something

Good comments, I'm going in parts.

To carry out the calibration process, the motorcycle must be on the center stand (according to the instructions) and there must be nothing that prevents it from moving (it tells you that you must remove the handbrake, engine off, etc.)

Regarding being in a kind of security mode, that has also been one of my initial bets, but I can't think of an idea of ​​how to get the computer out of that mode, although you have to take into account the errors indicated by the diagnostic tool... if it is in a "safe mode" it would not be logical to think that it should not indicate an error but should indicate that it is in that mode?

Could it be the reverse switch itself, as you say it does not beep, but was working ok before, part number 19 in diagram below, this I have heard also somewhere, that reverse gear switch was replaced because of intermittent reverse gear problems

https://oem-bike-parts.com/en/parts/piaggio/mp3-500/2020/mp3-500-maxi-sport-abs-e-4-2019-2021-nafta/electrical-system-selectors-switches-buttons

For sure one of the first suspects as all start... I have 2 of them, since I bought one at the first stages of the project because the one that came with the motorcycle had the D and R erased after two uses.

We did the tests with both, same result. I think both are fine, since when I put R the ASR light comes on and stays on steadily, until I turn it to D and it returns to its normal state. Make sense?

I can only imagine now that there is a faulty connection somewhere, it was working but then stopped after dropping engine, so maybe a wire has been snapped or pulled out of its socket but seems ok to look at, this is all I can think of or possibly here

Yes, that is a test that I have in plan do this weekend. I test the continuity from the connector to the ecu, and I can think that the connector in the solenoid side is good (as is new, and is statistically difficult for two connectors to be bad on the same part).

My plan is to test the continuity between the cables between the two sides with the connector in place, I am seeing how I can make (I bought them but they will arrive next week) some pieces that allow the cable to be "pierced" and thus be able to test. I was thinking of using some pins with some alligators to see if I can do it doing as little damage as possible to the cables.

The reasoning behind this is that, I know that everything works when energized (engine and solenoid) so it must be a logical signal to the ECU that prevents it from allowing the system to be activated and/or calibrated. Make sense?