Modern Vespa

Hi Group,

Situation is that even when the key is turned off the cooling fan continues to run. Dealer has told me they replaced the "relay", rode it for 25 miles and the fan continues to stay on. Back to the dealer and they have told me, we're tracing the short. According the wire diagram it's a pretty simple circuit. #34 electric fan remote control switch would seem to be the culprit. I know very little about electronics. If #34 goes wrong, would it stay open? thus causing the fan to continue to run? I believe that this is what they replaced when they told me a 'relay' was replaced. If it was something else wouldn't you think that it would turn off when the power was cut using the key? Any thoughts?.....

The "remote controls" (Italian translation for "relays") are spring-loaded to be normally open - that is, switched off when no coil current is applied. Normally-open relays generally don't fail closed (unless the contacts fuse together from overcurrent - but the fuse would have blown first). Your relay is probably good since it's been replaced. My guess is that the original was good too, because changing it out didn't fix the problem.

The coil curent to that relay is switched by the ECU. +12V is continuously available to the coil (while running), and the ECU completes the circuit to ground when it wants the fan to come on. The fuse that feeds the relay coil gets power only with the key on; but the fuse that feeds the relay contacts (and the fan itself), gets power no matter the key position, so +12V is always present at one of the relay contacts even with the key off. I suspect that the terminals or wires to the two relay contacts are shorted.

Try removing the relay; see if the fan runs like that. When you pull the relay, see if you can feel or hear it click as it comes out of the socket. Look for shorted terminals on the relay socket or pinched wires going to the socket.

I'm assuming the VIN on your GTS is above 001579 - the wiring scheme to the fan relay is different on VINs below that.

HEy Cin,

Thanks for your help. SHort discovered in the engine compartment! It's been at the dealer, my warranty is up in 10 days, they'll replace the suspect wire today. I read your post to them yesterday and it was like a light came on....thank you so much.

Hi Paddylamb,

You're very welcome indeed - glad I could help out. That had me scratching my head for a little while. I got a little lost thinking the relay coil might be getting pulled in by a short, but finally realized that couldn't be since the coil is cold with the key off. My post was a work in progress for about half a dozen edits until I finally had it worked out. Hope you didn't get to it until that was all over.

Wow, 10 days left on the warranty. Cutting it pretty close. Too often it seems this kind of thing happens just after the waranty expires.

Happy to hear you'll be back in the saddle soon.

Excellent! Just had this very same problemo and I have copied and pasted this to my dealer. Thank you to all involved!

Picked it up and it seems to be working fine. Thanks again!

OH MY GOD!!!!! I have this EXACT same problem. My scooter has been in the shop now going on 6 WEEKS! They are waiting on a new wiring harness. Why fix the short when you can replace every wire on the bike?

Tracing wires is too much like work...

Super! Did they say where the short was? Looks like you're not the only "lucky" one...

apparently it is a wire to the sensor that was actually the problem. It is a bit wonky on this model they said.

Funny enough, when I tried to start it about 12 blocks away from Vespa SoHo, it wouldn't start...so I pushed it back and they replaced the spark plug cap too.


Hopefully this is the end of my 'growing pains' and now I get to have some serious scoot-time on my new baby...with my honey perched on the back where she loves to be as well! ;o


At least with the fan stuck on, the sucker didn't overheat in the NYC traffic...so as problems go on a new beastie, could have been much much worse.



ciao,
R