Modern Vespa

Most strange electric failure 😊

if I am starting the bike and then power off every think working well.

however, if I am waiting more than 5 second when the motor running, the switch key will not turn off the bike.

since this failure start I notice ENGINE, ABS & ASR light are on

really appreciate any idea since I do not have any direction….

*MP3 - 500 - 2017

Ignition switch replacement?

Looks like the electrical contacts within the ignition switch might not be properly engaging or disengaging when the key is turned. If the contacts are loose then they might not be moving in accordance with key position leading to the bike remaining on.

Easy Parts is a great source; just make sure you select the correct model year and variant as there are slight differences between an MP3 400 within the same model year.

https://www.easyparts.nl/models/Piaggio-MP3-400-m2468

thanks for replay....

I also suspect at ignition switch at begin,
however when I am disconnecting the ignition switch plug the bike continue running as show in the move.

since I do have 2-3 MP3 for parts, I tried also replace the ECU and the result are the same

Electrical problems on a Italian vehicle? This is news. 🤣

Do check the basics first. Clean and tighten the battery connections as well as performing a load test on the battery.

Also check voltage at battery with engine running. You should see around 13,5v at idle and about 14,5V with some revs

If the tester shows the battery has a SOH (state of health) of 60% or less, the battery is toast. If between 60-70%, you should replace ASAP.

I find the Yuasa batteries to be the longest lasting, but unless you daily it any bike and modern cars should always use a smart battery charger like a Optimate4 which is the model ideal for bikes.

I am veteran with MP3 (since 2007), in fact, I think I owned all models of MP3 (125/250/300/400/500/fuoco) except the Hybrid version…

I already had many fights with many kinds of beeps, sensor, bearing and alignment.

this time I am very surprise with open mouth

I double checked the battery by using the bike LCD display and by using voltmeter, the battery locks solid and healthy, actually I am surprise that after so many starters without charging and still in force 😊 .

except this strange electronics behaver the engine failure light is on.

it looks like the ECU found a failure but I can not figure what is the failure since there is not any changes….

Assessing battery condition solely by measuring voltage is pretty much useless. It's all about the Amps and internal resistance.

There is also another issue going on. With the newest MP3s like yours, normally the ASR and ABS lights should be flashing alternatively until the vehicle reaches about 10km/h. Yours appear to be on solid.

Also, it appears your 2017 MP3 has 82K on the clock? If so, wow!

Regarding voltage check - I am using Fluke 77, this voltmeter has Min/Max feature.

also, remind the fact that if I am power off the key in the first 4-5 second everything working well,

the normal behivor is when switching on the ENGINE LIGHT on for up to 4-5 sec after engine start than the ENGINE LIGHT need to turn off.
in My bike the ENGINE LIGHT continue lighting all the way..
so, if I am understanding well, the failure appear only after the ECU complete system check and found engine error, at the first 4-5 the ECU still not aware about ENGINE error

regarding ASR/ABS - when I film the movie the + of ABS system was disconnected, today I notice about and I reconnected it back and just after starting rolling the two light are turn off.

the bike has ~29,800KM, tin the movie you see a replacement display for testing.
I do also have MP3-400-2011 with 165,000Km (unopen motor & original steering bearing)

The check engine light staying on is usually caused by a problem with the lambda a.k.a. oxygen sensor. Check connections.

Also be aware that oxygen sensors are wear and tear items and have a finite life.

I already needed to replace the oxygen plug as result of physical damage, there is a very good reasonability for failure.

I read in service Manuel that error record are store for at least 16 riding, see quote below…
is this mean that after repairing the failure I will need to wait 16 ride till the ENGINE LIGHT turn off or only the log will be clean and the light will go off immediately?!

"The control unit is fitted with a self-diagnosis system connected to a warning light on the instrument panel. Failures are detected and restored by the diagnostic tester. In any case, when the fault is no longer present, data storage is automatically wiped clean after 16 cycles of use (cold starting, running at regular engine temperature, stop). The diagnostic tester is also required for adjusting idle speed carburetion. "

I do have almost new replacement sensor, I will check is soon and let you know....

Unbelievable, problem has been found.

A faulty High/Low Beam switch !!!

(Total of 7 hours of investigation)

Whaaaaat????

Even for a Italian vehicle, that does not make any sense whatsoever.

Is this bike 100% stock electrically? No goofy 3rd party addons and the like???

100% stock !!!
if you will take the faulty switch to your bike, you will have this issue also.

try to follow my explanation than you will understand why

if you need the wiring diagram I can send it to you...

after starting the ECU count 5-7 second and than turn ON the front Headlight by using a relay.
(note - this relay getting power from ECU fuse)

- the low beam getting power from different fuse (not the ECU) (after suspend relay from ECU)

- the High beam getting power from different fuse (not as Low beam and not from relay)

as result of faulty switch the
the line of positive HIGH beam has been shorted to positive LOW bean.

so even when the ECU turn off the relay, the current still coming form high beam, and also all other systems getting also power by this passthrough.

I assume Piaggio toke power directly from fuse for HIGH beam (and not after the relay) in effort to give the ability to flash by using HIGH beam even when the bike is not running.

Last edited by Azencot Nir on Sat May 21, 2022 11:54 am; edited 3 times in total

RED is the power of Low beam (after ECU relay)

Green is the power of High beam (not ECU relay & different fuse)

Blue is switch High/Low beam

Blue - ECU relay
hope this will be more clear.

Italy. They may have invented electricity, but they perfected the art of electrical failure.