Modern Vespa

Hi all and a happy new year

New year and a new issue with my MP3. Seem that my fan will not shut off. Even when I switch the bike off the fan still runs. I have to pull the fuse or unhook the battery. The temp have been good here mainly in the 60F’s. I checked and added coolant but no joy. It happened about 8 months again also but stopped after not riding it and leaving the fuse out for a few days.

Temp on the screen is at most 3 bars maybe 4. Sensor issues electrical wire touching the frame? Any ideas
Thanks

There are two temp sensors in the same package. One feeds the ecu, which then controls the 'grounding' of the fan relay. The other just feeds the gauge.

The first step is to swap out the relay, which might have welded contacts. I think this is unusual, but at least it's free and easy to do! If that isn't it, check the resistance to ground of the sensor wires at the ecu connector, and at the dashboard. The wiring diagram has the details:
https://manuals.wotmeworry.org.uk/Piaggio/Piaggio%20MP3/MP3%20250/

you might have an air bubble in the system not allowing coolant to properly flow.

I hope that is the issue. I am flushing the coolant now and will see if that will cause the issue to cease!

In case thats not gonna resolve (and I think it wont) Where is the location of the Electric Fan relay? Looked on the wiring diagram and cant located it on the bike!

I also can see where a wire would be touching the frame, checked the usual places.

HELP

I am assuming its the quad relays under the windshield?

In which case the gauge would be spiking as well. So unlikely.

So I pulled the relays and obviously the fan went off.

I have put them back in and now nothing, Fan does not come on but the scoot wont start now, not even a try, i pushed the starting button and get nothing not even a sound

This sounds like an electrical fault. Maybe you blew a fuse now and that's why it won't start anymore?

Maybe I misunderstood, but your first post reads as though the fan is always on. So as soon as you turn on the bike it come on immediately, even though the bike is cold, Is that right?

If so, I'd say that reinforces an electrical problem because an actual coolant problem would still need a few minutes to heat up enough to trigger the fan.

Hey Berto.

Yeah it’s certainly an electrical issue.

The issue is/was that the fan is constantly running without the bike being turned on or started. It’s would only switch of when pulling the fuse or unhooking the battery.

Fast forward to where i am at now. I pulled the relays and as I said the fan went off. Inspection of the relays is that they are corroded. When I put them back in the lights and horn all seem fine and the fan does not come on. The problem now is that when I attempt to start the bike absolutely nothing happens. Does not even try. Seems like it’s dead. The dash all lights up and the brake lights work I have disconnected the kill switch too. Still nothing. I have ordered new relays. As this to me seems to be where the not starting issue began. I am picking one up from autozone shortly but will look to replace them all.

Okay so I managed to pick up 2 new relays. Put them in and still nothing. I’ll wait for the rest to arrive and have them all replaced.

How this has gone from the fan issue to not starting has me stumped. Like I said does not even attempt to start.

At a loss.

Must be something else. I am thinking also.

A quick look at the wiring diagram jimc posted shows the starting circuit passing through a couple of fuses, and the brake lights. Did you confirm (by multimeter test) that your fuses are good? Did you confirm that brake lights come on when holding lever and trying to start bike?

I got my new relays and put them in but no joy on it starting. Multimeter shows all the fuses are fine, but I replaced them anyway. Brake light come on using both breaks.

Checked the relay connections and the all read low on the multimeter. But one of the relay ports is reading a lot higher than the rest.

To be honest this is not something I am understanding but seems not right. It’s the brown connector that the relay plugs into if that’s important

What's the immobilizer light doing through all this? Does it light up when you turn the key, and then go out and stay off?

Could it be something simple and unrelated like a kill switch in wrong position or a sidestand down? Sounds good (well, not the part that the relay didn't solve the start problem). When you say the relay connections "read low", can you elaborate how / what you are testing? And what do you mean about one port reading much higher? Are you measuring resistance to ground? Continuity?

The light is flashing, when I turn the key to on the light continues to flash.

What I don't hear is the fuel pump whurring up.

I had a new fuel pump about a year ago, but this was not the initial issue. The bike was starting no problem but the issue was the fan being on all the time regardless of the bike running.

All I have done is pull the 4 relays loads and since then the bike will turn on but nothing when I try to start, does not even attempt to start. On a positive the fan is no longer running.

That then, is your elementary problem right there! No further diagnosis necessary! Either your ignition switch has failed or the connection to it has been disturbed - and as you've been in there to get to the relays I suspect the latter.

Check that before anything else. That obviously is NOT all that you have done. It may have been all you meant to do of course.

Latest news is it up and running.

I took a chances and bought an new relay harness, this was that the last thing I was prepared to do. Removed one off the relay harness that was giving a irregular read out and plugged new relays in. Turned the key heard the fuel pump whurring and hit the start button. Bless the old girl she fired up first time.

Put all the panels back on (easier to come off that’s for sure) started it up again and runs fine. Will test ride tomorrow for a few miles to make sure everything checks out.

Thanks for everyone’s help. It’s much appreciated.

Congratulations
Amazing

What was the part number or a photo of the relay harness , as I am sure it will happen to me 1 day

HaHaHaHa = 🎲 💨 💥 🎈🏁 ✅

Nothing fancy. I got these just used one of them.

Dollars to donuts the problem lies/lied in the relays vs. the harness.

So now it starts up *and* the constant running fan problem is gone too? The immobilizer light also goes out and stays off as normal?

I'm glad you got it sorted!

But must admit I am confused how the relay would have prevented the immobilizer from recognizing key and turning off the indicator light.