Faulty Throttle 1250GS

[Engineer]

Anyone else had a faulty throttle on a GS?

Mine starting playing up sometime ago - essentially when the throttle was allowed to close naturally the revs would not die back down to the correct idle of 1050rpm. The idle would fluctuate between 1050-1300 rpm.
The only way to get the revs to stay down at the correct value was to force the throttle shut in the same way as one does to disengage the cruise control.
My local dealer investigated and confirmed the issue and that a re-calibration did not fix the problem - so the throttle assembly was replaced, calibrated and everything is now good again.

I was curious as to the how the throttle worked - so I prised open the old one

To be continued .......................... with photos

 

[Santa-2512]

Common failure

I had one go on my fly by wire 2016

That was the start of the problem chain

 

[Engineer]

Photo of the guts - hall effect sensor is the shiny bit and the rotor section has an embedded magnet.
Very slight signs of wear on the rotor and the hall effect sensor surfaces, but nothing dramatic.
I am assuming that the hall effect sensor has failed in some way, but not dramatically enough to stop the throttle working completely, the bike was perfectly rideable.
There are 6 connections on this sensor, so maybe it is a dual sensor to provide redundancy and one of them has deterioted in some way? Water ingress?

 

[jetjock]

Photo of the guts - hall effect sensor is the shiny bit and the rotor section has an embedded magnet.
Very slight signs of wear on the rotor and the hall effect sensor surfaces, but nothing dramatic.
I am assuming that the hall effect sensor has failed in some way, but not dramatically enough to stop the throttle working completely, the bike was perfectly rideable.
There are 6 connections on this sensor, so maybe it is a dual sensor to provide redundancy and one of them has deterioted in some way? Water ingress?



View attachment 541425

I’d say water Ingress . Probably from a jet washer ?

 

[leadfarmer]

Is that spring the open throttle stop or the closed one that you push against to cut the cruise control?

 

[Engineer]

Is that spring the open throttle stop or the closed one that you push against to cut the cruise control?

It is the one you push against to disengage the cruise. There is another spring surrounding the rotor (hard to see) that is the normal return spring.

 

[Engineer]

I’d say water Ingress . Probably from a jet washer ?

I normally only use a hose pipe - when I have used a jet washer, I stand well back if get anywhere near the controls - but I guess there is a small chance. The hall effect sensor appears completely sealed - I'll prise that apart later.

 

[Engineer]

I tried dismantling the hall-effect sensor just for fun, but once the metal cover shown in post #3 is removed the unit underneath is sealed into the outer plastic moulding with some sort of hard silicone type potting compund - so short of attacking it with a hacksaw it is completely inaccessible.
Removing the potting compound cleanly would require a chemical attack so I decided to end the investigation.