Modern Vespa

Saw a post a week ago about the GTS fan runninng all the time. Now I can't find it. Who knows where the fan relay lives on the GTS? I seem to remember it is relay #34 from the original post.

Here's that original post:
GTS 250 Cooling Fan Stays on

The relay isn't labeled - it's at the top rim of the engine compartment beside the storage bucket, on the left side as I remember.

The shop pointed it out to me. Behind the horn cover, two yellow relys. I think that they're wrong though. Idiots-complete idiots. Trust what the Cincinnati kid is telling you. ( No offense John, it's a reference to a character from THe Kids In The Hall.)

Hey, no offense taken at all!!

Paddy, you're right! I just went in for another look. There's two relays under the horn cover, above the horn: the headlight relay (#21) is on the bike's right, and the fan relay (#34) is on the bike's left. (I tested it by unplugging the relay and shorting out the relay contact terminals in the socket - with the key off! - sure enough, the fan came on; wadaya know...) In the engine compartment, the "injection load" relay (#10) is on the bike's left, and the starter relay (#15) is on the bike's right. I feel better now...

I finally broke out the schematic. On my fan issue, the fan doesn't come on until the key is turned on, and then it stays on. Then as soon as I start the bike, the injection error light comes on on the speedo display.
On the schematics, it looks like relay #10 feeds relay #34. Would relay #10 be at fault for that since it feeds the fan relay (#34)? The shop checked and replaced relay #34.

I think your relay #10 relay is ok - it's the "permissive" that pretty much allows the engine to run - it switches power to the fuel pump, injector, ignition, and lambda probe - and is turned on by the ECU. It's going to be pulled in any time you've got the key turned on. What's the VIN of your bike? The fan relay coil is fed by relay #10 only on VINs below 001579; on higher VINs, the fan relay coil is fed directly by fuse #2 which is switched by the key.

In either case, the coil to relay #34 is switched by the ECU, and the contacts to #34 get power all the time regardless of the key switch. You don't have the same problem as Paddylamb did (short in the relay contact wiring) because your fan only comes on with the key switch - Paddy's ran all the time. The fact that the coil to relay #34 can only get power with the key on, that the ECU switches the coil to #34, and that you're getting an injection error light points to a fault with the ECU. Since you have the error light coming on, there will certainly be a fault registered in the ECU's buffer. Ask your dealer's shop to read the fault on their diagnostics tester. The shop should have done that if they knew the injection error light was coming on, and the fact that your fan was coming on only with the key should have told them that #34 was ok.

So the worst relay #10 could do would be to prevent the fan from running (on a low VIN bike), bit then it would prevent the engine from running too. Relay #34 has to be working, because the fan is turning on and off. It's just that the ECU has no control. The ECU itself could be faulty, but more likely the ECU side of the coil to #34 is shorted to ground. That could very well cause the ECU to register a fault, and a quick read around the forum will tell you that wiring shorts are happening all over the place all the time in these brand-spanking-new bikes. You could check for a short by unplugging relay #34 and dropping an ohmmeter between ground, and each in turn of the two coil terminals on the relay socket, with the key off. If you get continuity on either terminal, you have a short, either in the wiring or in the ECU itself.

Hope all this wordiness helps...

the vin is 001623. The shop has given up on finding the short. They have ordered a new wiring harness. I'm looking for the quick fix. They changed out the ECU and my fault screwed up the new ECU.

Man; I can't think of a quick fix offhand. You could just unplug the relay, but the ECU would still be looking at the short - and that would disable the fan. Finding shorts in harnesses isn't easy work - you have to trace the suspect wire from one end to the other, bundled up with other wires, inspecting as you go, through all kinds of tight spaces... Drives you cross-eyed.

Are you looking at the schematic in the Shop Manual? There should be 2 versions of the diagram in the manual - the first for higher-VIN bikes, the second for lower. The diagrams in the shop manual aren't very legible, so I re-drew my own diagram for the higher-VINs. Would be happy to e-mail it to you if you PM me your address. Now that I'm thinking about it Paddy, I'll e-mail it to you too buddy...

I've got the PDF files of the shop manual. They are legible enough for my purposes. I was seeing the difference between the serial numbers, some of them ran the fan off the headlight relay, and some off the ECU relay. Without looking at my VIN, I had figured mine ran off the ECU relay due to the Injection fault light coming on.
We have Gecko lizards in Texas, and they hang out in the engine compartment quite a bit. I'm wondering if the Gecko crap rots the insulation.
The big frustration for me now, is the dealer has given up on trying to troubleshoot it, and they have ordered a new wiring harness, and with the delay of parts coming out of Italy, it might be months before I have my scooter back. I'm so frustrated because I've missed 6 weeks of great weather here.
Thanks for your help on this.

Man, that's rough - watching 6 weeks of good riding weather get by.

There's an easy test you can do to see which schematic applies to your bike - With the key OFF, pull out the fan relay and short out the two relay contact terminals (heavier wires going to these terminals). If the fan comes on, your bike is wired according to the "high VIN" diagram; if not, it's the "low VIN" diagram.

I think "Injection fault light" is some screwy translation for whatever the Italians call it - "Status light" is probably closer to the truth.

Geckos in the engine compartment - that's a new one! I couldn't say if they're are doing anything to your insulation, but I do know that wiring problems are very very common in these bikes. The materials and mounting methods just aren't quite robust enough.

Anyway, pulling the relay might be your temporary "quick fix". It won't isolate the short from the ECU, though, and it will completely disable the fan. Provided the fault doesn't make the ECU go south, and if you avoid riding in hot weather, spend as little time as possible stopped and idling, and keep a close watch on your water temp, I think you'd be ok. Would have a way of draining a bit of enjoyment out of the ride, though.

Ask the shop to return the old harness to you - it's almost certainly repairable (provided they don't destroy it getting it out), and it would be a WHOLE lot easier to fix removed from the bike. Then you'd have a spare.