Modern Vespa

I seriously need some help here. I have a MP3 400ie, it has run like a charm for 5+ years that I've owned it. But then the battery died. I replaced the battery and now all hell.
To be specific, the tilt lock won't unlock, the seat sensor won't turn off and an alarm buzzes nonstop.
I just don't get this. All I did was replace the battery.
Please HELP!!!!
closest dealer said no appointment until September.

SOLVED!!!!!!!!!!!!
I checked the fuses by the footrest and all were good. I forgot about the fuses next to the battery.
well what do ya know. a blown 20 amp fuse.
I'm back on the road!!!!!!!!

update. never mind, problem was solved while typing out this reply. Was a blown fuse near battery.


When you changed the battery the wiring harnesses would have been jostled and probably stressed a bit.

One of the experts may eventually comment but you might get started with these steps.

* Check for shorts, frayed wires, blown fuses
* Is there any corrosion on the contacts
* Check both fuse panels. One near foot, one near battery, and maybe 3rd "hidden fuse" on some Mp3 variants.
* What is the voltage between the terminals of the battery and how does it change with the ignition on or off.
* Does the new battery have steady voltage and no damage (internal or external)
* What type or model of battery, make sure its correct for your bike.

Sometimes uploading a video of the problem to YouTube then sharing the link here can help the experts narrow down the issue.

Is there a thread on battery replacement somewhere here?

My original battery is now 2.5 years, so I assume it'll need replacement soon - correct? What are the best replacement options? It still shows well over 12V when turned on and over 14V when riding around, if I can trust the display.

Thanks as always!

I got a NOCO Lithium NLP14 battery recently. Shaved a few pounds of the bike, not enough to make a real difference but every little bit above the center of gravity helps.

https://www.amazon.com/gp/product/B091P9QXX7/

Installing the battery is one of the easier tasks on the MP3. The battery (and main wiring harness / fuses) are located under the seat towards the front of the luggage compartment. There are a few torx screws that need to be un-done then the plastic cover lifts off. Under the cover will be the battery held in by a simple rubber strap, fuses, the pigtail for the aux power, and some other goodies.

I forget if the Lithium battery came fully charged or not so I got a NOCO GENIUS10 to go along with it and let it charge overnight. The NOCO GENIUS10 is over-kill but I use it on other vehicles and it was on deep discount at the time so why not.

https://www.amazon.com/gp/product/B07W3QT226/

After changing the battery your presets on the MP3s console will reset to factory including the clock. Consult the MP3 manual to change things back to your preference of imperial vs metric and set the clock properly.

Thank you as always!

Yep lithium ion is great BUT if you plan to ride on cold days (sub 5C/40F) you better give it 1 minute of headlight action before hitting the starter button.

Otherwise, the membrane inside the battery can be pierced and cause a instant short circuit.

Another point, lithium is still a developing technology in the same way as LED headlight tech. Getting there, but not quite.

uugghh. stupid me left the trunk open and drained the brand new battery.
I charged it and I got the same problem. Tilt won't unlock and seat sensor won't sense.
I checked all the fuses but this time they were all good.
That's when I was introduced to the "hidden fuse". Yep that rat bastard was blown.
I'm running again but honestly I'm afraid to go anywhere. I keep thinking it will happen again and I will be miles from home.
Not a good feeling at all. and the MP3 has run so perfect for the years I've owned it.

you should be good, I would ride for an hour and back to the house and check your readings, if all good take it on a trip.

if your overly concerned carry one of those small jump packs.

This does nothing for a Lithium battery, their internal resistance is so low (milliohms) that you could draw 300A and it wouldn't warm up in one minute.

A heater pad underneath is the answer.