STVA Constantly Cycling

[jeremyp]

I’ve searched but can’t find anything.
When I turn the ignition on, the STVA constantly cycles/buzzes - you can see the butterfly opening/closing/flickering.
There is no FI light.

Any ideas as to what the problem is? I’ve searched the internet but can’t find a solution to this particular problem.

(I’ve only just bought the bike and it’s been like this since I’ve had it)

Thanks in advance.

[jeremyp]

I’ve opened up the STVA and all the cogs seem to be undamaged.

[knight2]

I had a quick look on the internet but they all seem to have the F1 light on. There's some stuff on burgman USA and some on mitchs scooter stuff, there's some info in the comments as well. I would put a link but don't know how to on a kindle

[Data]

Try disconnecting the battery for at least 60 mins (can't actually remember how long exactly to disconnect for but this should do it). This should reset the ECU. Then reconnect the battery, DO NOT TOUCH THE THROTTLE, turn on the ignition & wait several seconds to allow the dials to sweep & the stva to position itself. Start the engine. It should be fine if the stva is functioning correctly. Come back to let us know if this works. And...good luck!

PS. It's possible to reset the ECU by going into dealer mode. A paperclip can be used to reset it by bridging two of the connectors but again I can't remember which ones. It's been near 20yrs since I had the 650. You can look it up on YouTube or Burgmanusa.

[knight2]

sorry I thought it was a 400.

[jeremyp]

Thanks Data - your'e a star

It's a 400.

I have a dealer mode switch so I'll try that and let you know

[Data]

Sorry was thinking it was the 650 but it works the same for the 400 too.

[jeremyp]

Tried resetting the ECU by disconnecting the battery for an hour (didn’t know if the dealer switch had done it).
Turned ignition back on and it immediately went back to cycling the STVA.

Here it is in all its glory:



There are no error codes!

What do I do now?!

[jeremyp]

Using the service manual, I’ve checked the voltages of the STP sensor and those are as they should be.
I’ve tested the continuity between ground and the pins of the STVA - all good. I’ve tested the resistance between the pins of the STVA - all good. I’ve tested the continuity between the connector on the STVA and the ECM - all good.

So the diagnosis is a faulty ECM - really???

[jeremyp]

I’ve saw this post on burgmanusa: https://www.burgmanusa.com/threads/bad- ... st-1050593 but can’t completely make sense of it as there’s no way to turn the STP sensor before putting on.
So I mounted the STP and went through the procedure in the service manual to set the position (measuring the voltage at closed and open positions of the butterfly). No improvement to the STVA cycling.

When I had the STVA disconnected so I could set the STP, I noticed another clicking on startup , as heard in this video.



I disconnected the ISC and the clicking stopped, is this expected?

I still don’t have any error codes!