Stepper motor

[Hp006]

I got my bike about a month ago with full bmw service history to 32k. The bike had done a 1k more by the current owner when I purchased it but it hadn't been serviced in 3 years. Therefore it now sits at 33k.
I thought I'd take it to my garage to get serviced. He stated that he thinks the stepper motors are out and need replacing.
The bike is sluggish when pulling away and trying to accelerate. I don't know if this was just down to the gearing as I've read you have to keep these above 3000rpm. I know my k1200lt was smoother.
Mechanic who service bikes used to work for BMW and said take it to them to plug in at Witham. Took it there and came back with no faults however they did say my pivot arm had slight movement and they suspect the idling to be down to the secondary coils.
I have replaced these same issue, even my mechanic said issue is still there and certainly no play in pivot arm.


I have managed to get 2 stepper motors but he reckons it'll take 2 hours to change these. Bmw did do something useful and calibrated the actuators.


My questions is if I replace the stepper motors is it a straight forward swap or is there calibration that's required? Can see there just behind the side fairings. Just trying to work out why 2 hours is needed. The garage is fair that I go to as well

[Qball-16]

Stepper motors can lose their 'count' and cause rough idle and stalling, but each key-on cycle re-sets them at their zero.  Plugging into a GS-911 can re-zero them (and lock them out at zero for throttle body balancing as well). From what I understand, diagnosing a bad stepper motor is almost impossible.  You essentially have to replace one side with a known good stepper motor, and if the symptoms go away you're done.  If not, you swap the known good motor to the other side and try again.  I got lucky when I replaced one of mine and got it on the first try!  My RT would occasionally not idle and stall, but only after long stretches at speed on the highway.  A couple times I pulled off the highway into a fuel station and it would stumble and stall - until I turned the key off/on, for it to go through the start-up cycle and re-zero the steppers.


Two hours seems a bit excessive, to me.  Both the upper and lower side panels need to be removed, but that should only take a competent mechanic 15-20 minutes - if that.  I've done it enough times on my own RT, that it's barely a 10 minute job.  Maybe.  Once the panels are off, replacing the stepper motors is a 5 minute job at most (both sides).  Two screws and a wiring harness, and it's all easily accessible (once the panels are removed).  Another 15-20 minutes to reinstall the body panels, and that's it.  OK, maybe another 5 minutes with a GS-911 to calibrate/zero the motors, but it should be well under an hour of work - and that's being generous.


If you are in any way mechanically inclined, it's a SUPER easy job to do yourself.  If you've never done it before, there are a ton of youtube videos out there on how to take the panels off, showing the sequence and location of all the screws.  The stepper motors are dead simple too.  Basic hand tools are all you need, and you'll learn a LOT about your bike while doing it!

[David.]

My question is if I replace the stepper motors is it a straight forward swap or is there calibration that's required?

Does this help to answer the question, http://www.hexcode.co.za/techinfo/iac

[Hp006]

Thank you for the responses.


So I need a gs911?


Changing the parts seems easy enough. The fact bmw just calibrated them this needs doing again?


What happens if I just swap them over? The mechanic at my garage does not have any diagnostic equipment so not sure how he was going to do this and calibrate them?

[David.]

So I need a gs911?

Could always give this a go, https://www.r1200gs.info/forum/14-maint ... 911-a.html

[Qball-16]

Thank you for the responses.


So I need a gs911?


Changing the parts seems easy enough. The fact bmw just calibrated them this needs doing again?


What happens if I just swap them over? The mechanic at my garage does not have any diagnostic equipment so not sure how he was going to do this and calibrate them?

The key ON start-up sequence automatically re-zero's the stepper motors, so a GS-911 isn't absolutely required.  I suspect it puts the steppers through a slightly more thorough calibration than it goes through on the start-up procedure, but the BMW tech I spoke to when I did mine said it wasn't necessary.  Just make sure to give the computer enough time to complete the start-up procedure BEFORE actually starting the engine - no more than 5-10 seconds (or when all the buzzing, clicking and whirring stops...)


I have a GS-911, so I used it to calibrate anyway.  It's good for sooooo many other things, that I felt it was a worthwhile purchase.  It could save me $$ in the long run as I won't have to take it in to a shop to deal with a lot of maintenance & repair issues.