Intermittent HISS/FI issue

Good morning,

I have a very weird, and extremely intermittent issue.

The bike is usually running just fine - no problem whatsoever.

But every now and then, during the ride, a HISS + FI lights comes on. While riding at a higher speed, you can also feel a bit of a slowdown (for a fraction of a second), and with lower RPM, the engine will actually shuts down.

This is very hard to reproduce. My observations so far:
1) It usually happens, when the bike is leaned left, and/or the steering is turned left
2) Bumpy road, or any sort of shaking movement - seems to contribute too. I.e., riding out of curb seems to be a good way to reproduce the issue
3) It doesn't seem to be connected with the weather, fuel level etc
4) When it happens, on top of the FI+HISS, cooling fan is cut (if it happens to run), and so is fuel pump (you can actually hear it starting)

It's almost impossible to reproduce in the workshop. To be fair, the bike can ride just fine for weeks - and then, out of the blue, it can happen 3 times on a course of a mile.

What I did so far:
1) Replaced all the fuses with brand new, while also cleaning the sockets - no change
2) Under the left side cover - cleaned all the relays, and shuffled them around. While at it, also cleaned all the connections I could find
3) Lean angle sensor - replaced with the new one
4) Side stand switch - inspected, all good. Also the symptoms doesn't really match (ie. side stand doesn't kill the cooling fan)
5) Kill switch cleaned and inspected.

You can reproduce the exact symptoms by very briefly flipping the kill-switch, or by disconnecting the lean angle sensor. I haven't been able to reproduce the issue as such - no matter how much I poke around.

Any ideas for what to check next?

SWAG, a bare wire / connector somewhere or one that's broken and reconnects when the wire (s) are moved again. Nothing worse in my book then an intermittent electrical issue. Good luck with it and when resolved please post the answer

As OWG says ^^ it sounds like a wire breaking connection or shorting to ground.

IIRC The majority of the wire harness runs along the left side of the frame. So you might start by removing the left side panel (with the trunk lock) and checking the (2) plug connections at the ECM. You can remove the seat and seat undercover and continue checking connections, looking for signs of abrasion and twisting & wiggling the harness as it goes forward. Then you could remove the tunnel cover (pull up the floor mats and remove the screws there and the lower screws at the fuel fill cap) and continue checking the harness.

Of course you’ll have had the engine running while doing all that twisting & wiggling.

Now comes the more difficult part*. You’ll need to remove the windshield garnish, windshield, Front Cover and the panel over the Combination Meter. Check the wiring in those areas.

Next remove the handlebar covers, the Inner Cover and the floor upper cover. Continue following the wire harness up from the areas you’ve previously inspected. Carefully inspect the wiring near the steering stem for signs of abrasion.

Please let us know how you get on with this issue. We all benefit from shared information.

* https://www.youtube.com/watch?v=5uv2qyxA-AA&app=desktop

Afternoon,
eventually, I decided to bite the bullet, and virtually tear the scooter apart.

The problem was as you both expected - a lose wire connection, but it was a bit weird one. In the part of the wire loom, that run across the scooter, under the seat, I've found a broken connection. What's interesting, is that this is a very odd one - effectively, 7 similar colored wires, merged together.
One of those wires were ever so slightly lose - and it was the root of the issue.

It looked sort of guerrilla, but judging by the look of the area - it came like that from the factory.

Any idea what is it, and why was it made like this?

Without looking at my SW, I can’t say for sure what that piece is but it looks to be some kind of wiring protector. The green-ish wires you’re holding are most probably ground (earth) wires for some circuits. Green is the traditional color for ground wires to frame.

Good job finding it, when we have two wires come together and ground out and blow a fuse we refer to it as a short, have you found a long

Good find. It's a common thing among manufactures to joint many wires to a single ground point. Crimp or solder came loose. The larger wire most likely goes to a ground bolt on the frame.

Power to ground a short blows fuse. Open grounds are the hardest to find. DC electrical has it's problems. You can check it with a volt meter and shows continuity but if it's just hanging on by 1 strand of wire it's not enough to carry the load-voltage to work.

Oh, okay. Now I “see” it. That big wire end is actually a broken piece of the frame-ground terminal. The plastic thing is a protector sleeve for that bunch of Green and Green + color ground circuit wires all connecting to that frame-ground terminal. 

Thanks Mech 1.