Throttle problem or CC switch?

[Chris Terry]

I have just had new spots installed at the dealer and while it was there a software update installed (something to do with the improving the throttle response I think). On the way home I noticed that the Cruise Control will only work if I don't move the throttle twist grip. The speed will hold and follow the CC as it should but if I release the twist grip (it returns to rest position) the CC light goes out and CC disconnects. The dealer insists the CC switch needs replacing (which he doesn’t have in stock).
I believe that the throttle (or the software that controls it) is the problem, and just needs setting after the new software upgrade.
I assume if you’ve read this far you must be an engineering/tech type (like me) and may have an opinion, or may have a circuit diagram.
Any ideas?

 

[mcinlb]

It does sound like the throttle stop "switch", normally it would require you to make a positive movement of the throttle past the stop to take off the CC.
Letting it return to normal stop obviously should not operate the CC off control...

 

[Hammam]

The throttle grip is not supposed to go back to its closed position, when you turn on CC. It stays right where it is if you let go of it, which is the whole idea behind CC, right? My CC switch started behaving erratically a few weeks ago. It wouldn't stay on. As soon as I let go of the throttle, it went off, and the throttle closed. Turned out several switchgear units were defective on a batch of WCs, and needed to be replaced with - in dealer lingo - a new reference number. Mine was, under warranty, and eveything went fine for a couple of weeks, until I rode under a severe shower the other day. And sure enough, the CC stopped working again the next day. So now my dealer is going to check if the new unit they put was indeed the new reference number or the same as the original.

Now, a few people have suggested the problem could be a too sensitive throttle. And it's true, that when you'r on CC, the lightest touch of the grip can sometimes turn CC off.

Keep us posted. I will.

 

[Appman]

The throttle grip is not supposed to go back to its closed position, when you turn on CC. It stays right where it is if you let go of it, which is the whole idea behind CC, right?

When the CC is set only the speed stays constant, let go of the throttle grip and it returns to the stop. Slight forward turn and CC is dropped of and the bike will reduce speed. Grip position Certainly does not stay at the position it was when CC was set. How can it, it is no longer a mechanical connection nor is there any solenoid on the grip to hold position.

 

[Chris Terry]

When the CC is set only the speed stays constant, let go of the throttle grip and it returns to the stop. Slight forward turn and CC is dropped of and the bike will reduce speed. Grip position Certainly does not stay at the position it was when CC was set. How can it, it is no longer a mechanical connection nor is there any solenoid on the grip to hold position.

I agree the only thing to stop the throttle returning to the "closed Position" is your right hand.
I find it difficult to believe the left hand bar switch cluster is at fault because the CC behaves as it should as long as the throttle is not allowed to closed. That coupled with the "software upgrade" that appears to have started the problem.
I wonder if part of the software upgrade process involves calibrating the throttle to it's extremes (fully open & fully closed), and mine was not done?. I don't know for sure but I think the CC control is just momentary contacts to signal the ECU, and has no effect on the throttle control or indeed any other "direct" electrical connection.

 

[Hammam]

When the CC is set only the speed stays constant, let go of the throttle grip and it returns to the stop. Slight forward turn and CC is dropped of and the bike will reduce speed. Grip position Certainly does not stay at the position it was when CC was set. How can it, it is no longer a mechanical connection nor is there any solenoid on the grip to hold position.

Then, we don't ride the same WC. My grip stays right where it is. I suggest you check yours ASAP.

And how, pray, can you give it a «Slight forward turn» if it has returned to the stop?

 

[Roymondo]

And how, pray, can you give it a «Slight forward turn» if it has returned to the stop?

According to the owner's manual, you do indeed de-activate the Cruise Control by giving the throttle grip a "slight forward turn":

"Deactivate Cruise Control

Brake, pull the clutch lever
or turn the throttle twistgrip
(close the throttle by turning
the twistgrip back past the
idle position) to deactivate the
cruise-control system."

Maybe Canadian bikes are different in this area?

 

[Hammam]

According to the owner's manual, you do indeed de-activate the Cruise Control by giving the throttle grip a "slight forward turn":

"Deactivate Cruise Control

Brake, pull the clutch lever
or turn the throttle twistgrip
(close the throttle by turning
the twistgrip back past the
idle position) to deactivate the
cruise-control system."

Maybe Canadian bikes are different in this area?

No, they're not. Come on! I have the exact same manuel, and we deactivate CC exactly the same way. What I am challenging here is that the grip goes to the stop position when you activate CC and let go of it. This is clearly not my experience. The grip stays right where is it (it has to.) It was exactly the same on my 1200 RT. And, for instance, if you accelerate using the grip while on CC, then let go of it, the grip will go back to the previous memorized speed position, not the the stop.

And I am asking how can one «turn the throttle past the idle position» if it's already there. Does not make sense.

 

[Roymondo]

No, they're not. Come on! I have the exact same manuel, and we deactivate CC exactly the same way. What I am challenging here is that the grip goes to the stop position when you activate CC and let go of it. This is clearly not my experience. The grip stays right where is it (it has to.) It was exactly the same on my 1200 RT. And, for instance, if you accelerate using the grip while on CC, then let go of it, the grip will go back to the previous memorized speed position, not the the stop.

And I am asking how can one «turn the throttle past the idle position» if it's already there. Does not make sense.

What happens to this "Previous memorized speed position" when you ride from level ground onto a reasonable uphill gradient? Or when you start going downhill? My own GSA doesn't have CC, but when I played with an RT recently that did have it (I think the system is the same as on the WC GS) the twistgrip would always return to the "idle" position when released (i.e. "hands off") even though the CC maintained the desired road speed. Just as the manual states, CC could be deactivated by rolling the twistgrip *past* the "idle" position (or by applying the brakes or operating the clutch). Far from making "no sense" it seems to be quite sensible.

 

[Hammam]

What happens to this "Previous memorized speed position" when you ride from level ground onto a reasonable uphill gradient? Or when you start going downhill? My own GSA doesn't have CC, but when I played with an RT recently that did have it (I think the system is the same as on the WC GS) the twistgrip would always return to the "idle" position when released (i.e. "hands off") even though the CC maintained the desired road speed. Just as the manual states, CC could be deactivated by rolling the twistgrip *past* the "idle" position (or by applying the brakes or operating the clutch). Far from making "no sense" it seems to be quite sensible.

The problem I have with «past the idle position» is that it's a wrong statement from BMW. Idle position is all the way forward top the stop, so there can't be any «past the idle position.» I fact, the tiniest movement of the throttle grip forward will deactivae CC. You do no have to go to the stop for that.

But I'm afraid all discussions from this point on will probably be pointless, so I suggest you go ride your WC, switch on CC, let go very carefully of the throttle, and pay good attention to it. I'd be darned if it moves the slightest. Also try and find a road with some hills to ride up, turn on CC and just very slightly feel the grip, You will feel it turning a bit to maintain the same speed.

One last question, though: how on earth would the throttle grip be suddenly dissociated from speed and gas control so that it could return back to the stop, or closed position, with the bike maintaining the same speed?

 

[alp]

Hamman, the throttle is just a position sensor. If your bike doesn't have a 'past the idle position' then there's something wrong with your bike. You just turn the throttle grip back beyond its natural stop or 'idle position' and the sensor in the throttle senses that you want to turn off the CC.

There is no mechanical cable connection or motorised system within the throttle to make the throttle grip move, only your hand. How could it control the bike's speed if you're holding the grip otherwise?

Regarding how the grip can be 'disassociated from speed and gas control', it can because, it's just a position sensor. When the CC is on the engine is being controlled by the ECU via the CC system, not the throttle grip, until you either turn the grip further beyond the CC setting to go faster or close the throttle 'back past the idle position'.

 

[iandavid]

Firstly, unlike my previous RT, on my WC there is NO mechanical link to the throttle bodies from the grip hence when CC is activated the throttle actual returns to the idle position even if you are still holding it open, IYKWIM.

You can disconnect by applying a little extra closing force to the throttle grip in the idle position. It is a miniscule amount.

I don't know if mine is working properly because it can be a bit disconcerting when bombing along at say 80 on CC and just touching the front brake and suddenly the throttle goes to idle, where the grip is positioned and the bike suddenly slows rapidly. Enough for SWIMBO. To bang into me.

When I disconnect CC I have to reset the grip in the approx position representing 80 and then touch the brake to disconnect.

Anyone wiser on this issue?

 

[mcinlb]

Yes, if you take the CC off by any means while sitting at 80ish, it slows like running into a sandpit. You get used to readjusting the throttle as you taking it off to reduce this effect.

Gives further credence to the throttle NOT being maintained at the CC set position when taken off...........

 

[Chris Terry]

Hi, Sounds like most of you confirm my understanding of the CC operation/control. That still leaves the question of what is causing my problem "Throttle twist grip OR left hand bar CC activation switch". From what's been said I still believe I have a Throttle position issue, I also believe that a setup/calibration (software-twist grip) should resolve.
Anybody agree?

 

[Hammam]

Yes, if you take the CC off by any means while sitting at 80ish, it slows like running into a sandpit. You get used to readjusting the throttle as you taking it off to reduce this effect.

Gives further credence to the throttle NOT being maintained at the CC set position when taken off...........

If you do not HOLD the throttle grip, it does slow down «like running into a sandpit» when you turn CC off by any other mean than turning the throttle forward a tiny amount (which is what I do most of the time, and that is several times a a day every day), and that's because the grip WILL suddenly TURN all the way down to idle position. Only possible if it had been left open when CC was turned on. Which is what I say: the throttle stays right where it is when you turn on CC.

 

[Hammam]

Hi, Sounds like most of you confirm my understanding of the CC operation/control. That still leaves the question of what is causing my problem "Throttle twist grip OR left hand bar CC activation switch". From what's been said I still believe I have a Throttle position issue, I also believe that a setup/calibration (software-twist grip) should resolve.
Anybody agree?

I guess you have what I had, which is a problem with the CC switch. Try spraying some electric contact cleaner into the switch and see what happens. If you still have the problem, you need to have the whole switchgear changed. But make sure they replace it with the new model (reference number.)

 

[Hammam]

Hamman, the throttle is just a position sensor. If your bike doesn't have a 'past the idle position' then there's something wrong with your bike. You just turn the throttle grip back beyond its natural stop or 'idle position' and the sensor in the throttle senses that you want to turn off the CC.

There is no mechanical cable connection or motorised system within the throttle to make the throttle grip move, only your hand. How could it control the bike's speed if you're holding the grip otherwise?

Regarding how the grip can be 'disassociated from speed and gas control', it can because, it's just a position sensor. When the CC is on the engine is being controlled by the ECU via the CC system, not the throttle grip, until you either turn the grip further beyond the CC setting to go faster or close the throttle 'back past the idle position'.

My bike is perfectly fine. I believe BMW made a mistake when calling that point the «idle position.» This is obviously a bad translation from German. It wouldn't be the first time they did that. I think they mean from it's «set position» (where it was set when turning CC on). In fact, my French manual (I have both English and French manuals) does not refer to the «position de ralenti» («ralenti» being French for idle) but «position de base, or «base position», which, while still a bit vague, makes more sense.

And, better than a millions words, this is eaxactly how I use CC every day.

 

[alp]

I think they mean from it's «set position» (where it was set when turning CC on).

No, actually. They really do mean the position the throttle grip is in when the engine is at idle/tick over/closed not the position the throttle was in when you set the CC. From that position i.e. the position the throttle is in when the bike is stationary and ticking over, you can turn the throttle back past that point to deactivate the CC or operate the brake/clutch if you wish. That idle/tick over/closed throttle position is nothing to do with where it was when the CC button is activated/set. The ECU electronically knows what the throttle position/speed was when the CC was activated/set and as far as the ECU is concerned it ignores all throttle grip movement except a) closing the throttle past the idle/tick over/closed position to switch CC off or b) additional turning of the throttle grip further than the CC setting to go faster.
I'm trying to think where you're coming from with your comments about having to hold the throttle, It's not a translation issue. I know you don't have to because I can ride along on CC with both my arms folded (he says quietly). Maybe, just maybe, the return spring action on your throttle is so strong that when you take your hand off the throttle with CC activated it springs the throttle back with such force it activates the 'past idle position' switch to deactivate the CC, causing the bike to use its engine braking to lurch the speed down, like running into a sandpit as mcinlb says. When I want to turn off the CC I dip the clutch and match the throttle to road speed for a smooth transition.

 

[iandavid]

As an addition, i always leave the master CC switch on and just touch the flapper when i want to activate.

Despite all the niggles it's great for relieving a tired right wrist.

 

[Chris Terry]

I guess you have what I had, which is a problem with the CC switch. Try spraying some electric contact cleaner into the switch and see what happens. If you still have the problem, you need to have the whole switchgear changed. But make sure they replace it with the new model (reference number.)

That's the thing, the CC switch does everything its supposed to do (hold speed, increase speed, decrease speed) IF I maintain holding the twist grip from returning to the "rest" position. So how can it be the CC switch?.