Modern Vespa

I've got a 2005 LX 150 that I've owned since new. She turns over but won't start. I replaced the coil wire and plug and still nothing. Tried jiggling the ignition switch and she started up. After replacing the ignition switch with a new one I'm back to square one. Not sure where to go from here but it seems like it's in the ignition somewhere. Can anyone with experience with this issue give me some pointers? Thanks!

do the brakes lights work ? front? rear?

Yeah brakes in the rear work, lights come on like they should etc.

When was the last time it was running?

If the "Engine stop relay" is dodgy, it will turn over but won't start. Try replacing that - swapping with the headlight relay perhaps.

I haven't ventured past the coil, plug and ignition switch. It turns over fine but maybe its the relay?

2 days ago when I jiggled the ignition switch wires around.

As I said...

I swapped the relays like you said and she started up! When I switched them back it also fired up but my guess is just replace both relays. Thanks again.

Once again, our resident Vespa guru, jimc, comes through with the correct diagnosis and repair without visual or touchy-feely of the machinery. We are extremely lucky to have him on our volunteer payroll.

Indeed. I'm quite impressed myself!

It was merely a matter of looking at the circuit diagram for components that if faulty could cause the symptoms, and in this case there was just the one. QED...

JimC, it appears as if I was looking at the wrong relays. I removed the battery panel and found the actual starter relay. Its corroded so bad it almost fell apart while pulling it out. Do you happen to know what the name of the part is that the relay plugs into? Attaching some pics. Thanks.

Yuck! That needs replacing! Battery acid attack.

You can buy 80/90A relays complete with socket on Amazon quite cheaply. You'll have to solder and heatshrink the new wires onto the old ones.

However, that won't have been the original culprit, as you say the engine turned over - i.e. the starter relay was still working - amazingly!

Yeah I'm shocked it was working at all. The closest thing I'm finding on Amazon is a 5 pin but it is 80amp. Guessing I can just use 4 of those pins to make it work?

Yes - just ignore the centre pin. I've used these ones for high current stuff in cars etc:
https://www.amazon.com/dp/B0CNLBW59N

Yes, I know the advert incorrectly states it's SPST, when it's actually SPDT....

Thanks for the link Jim. I ended up finding a 4 pin relay/socket combo very similar to the one you sent. Scooterwest got back to me yesterday and said Piaggio stopped making the socket side which used to be part of the harness.

When I swap over to the wires it looks obvious where the 2 larger red wires go. Do you think it matters on the smaller ones? Hoping I don't do any damage.

It's not polarity sensitive - so no worries there.

I ended up buying the Piaggio starter relay and the Amazon combo. To my surprise the Piaggio relay pins fit perfectly inside the Amazon socket. I wired everything up and voila!