Modern Vespa

MP3 500
Was riding down the road, pulled over to fill up, now it will not go off idle when given throttle, acts like the tilt lock is on.
Instrument panel is not working either
The red security LED is blinking as usual when I turn ignition off, led goes off when I turn ignition on.
No headlights either when it's running.
Sitting at a gas station waiting for my brother to show for the trailer.

I did reach up to the instrument cluster and make sure it's still plugged in, it is.

Sure sounds like a blown fuse or a bad connection to one.

Should have put I checked off uses. Replaced one that looked funky but turned out to be good when I looked at it better.

I sort of assumed you had. However, the fuse-box by your foot is especially prone to having corrosion in the fuseholders and in their crimps. If they weren't given a smear of dielectric grease early in life that could still be the problem even if the fuses themselves are AOK.

Just a thought.

sounds like ignationswitch to me

Well thanks to my fantastic and loving brother I made it home. He drove me three and a half hours home, now he just left to drive the 4 hours back because I was half hour from his house. Plus it's memorial Day weekend so we'll most likely be closer to 6 hours for him. God bless him.

First thing I'm going to do is pull all the fuses again and test them with a meter just to make sure they're all good. The fuse is by the foot panel I'll look good I did dialect grease them thanks to your advice Jim when I bought it.

First thing I think I need to look into is what circuits will prevent the motor from revving up? I have quite a few extra parts for my parts bike. So I can swap parts. All advice from experienced diagnostic people welcome.

I have a spare ignition switch, what's the easiest way to swap it out?

Can the instrument cluster cause all these symptoms?

I think I recall reading that there's a switch in the seat that prevents the engine from revving up when there's no rider seated. Perhaps that switch or its circuit are faulty.

Doesn't explain the instrument cluster though.

Sorry that was wrong. Last post deleted, it is not fixed. My bad I was just being stupid and saw lights that I couldn't see in the bright sunlight. Everything that wasn't working still isn't working.

The wiring diagram suggests that fuse 11 (7.5A) would prevent headlights, instrument panel, seat switch, horn and tilt-lock 'ECU' from working.

Second one from the front by your foot according to the user manual.

Easy way to check the full path is to check the horn works.

Thank you very much my good gentleman.

Horn does work.

Ah, my mistake - the usual horn button will work fine, being fed from fuse 9 - it's the horn relay operated by the ECUs (yes, both) that won't work.

So back to the fuse 11 circuit - check for volts at the seat sensor connector.

Put a meter on the fuse after I pulled it and not getting continuity. Replaced fuse and everything is working.
Looking at the fuse I could not tell it was blown until I put it under my magnifying light. Very fine fracture in the filament.

Will be caring extra fuses with me till I figure out why it happened.


Thank you so much Jim and you have a fantastic memorial day weekend.

Sounds like it just died, rather than blew because of any fault condition. Fuses are only very dim light-bulbs anyway, so they have a limited life.

I have a ton of fuses, maybe I'll just replace them all to be safe and check the hidden fuse too, been a year or two since I've looked at it.

I also ordered these for my fuse kit. Will clean all the fuse sockets in the blocks.
Lisle 55040 Fuse Puller & Terminal Cleaner, 2 pc. https://a.co/d/3zPzWOl