Speedo Failure

Having Problems with your BMW R1200RT/R1250RT? or have some Maintenance and Service questions?
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David.
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Re: Speedo Failure

Post by David. »

Do the Speedometer & Odometer work off the front or rear ABS speed sensor.
STeinar
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Re: Speedo Failure

Post by STeinar »

David. wrote: Do the Speedometer & Odometer work off the front or rear ABS speed sensor.

From all ones I have worked on - its taken from the rear
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David.
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Re: Speedo Failure

Post by David. »

STeinar wrote:From all ones I have worked on - its taken from the rear.
As per the Haynes Manual too.
rangemaster728
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Speedo Failure

Post by rangemaster728 »

OK...

My nephew just brought over his ‘05 RT to roost for the winter.
He’d previously left it in storage for a few years in Arizona and shipped it up to the Pacific NW last year so I did a lot of service work on it to get it roadworthy.

This included oil/filter change, spline lube, flushing the tank and replacing the fuel pump, completely flushing the brakes including the servo ABS system, etc.

The reason I mention this is I now have 2 RTs in the garage...my ‘09 and his ‘05. I’ll use his ‘05 to investigate this as it is has the same braking system computer as the OP.

I’ll fire his up later today and try this test:

1. While on the center stand I’ll jack the front end up, turn on the ignition and spin the front wheel to see if the speedo starts to indicate.
2. I’ll then lower the front wheel (the rear is now off the ground), put the bike in gear and (carefully) advance the throttle to spin the rear wheel and see if the speedo indicates anything.

This will show if the speedo needs just one sensor input to function - and if so, which one is needed.

There is also the possibility (knowing German engineers) that the speedo requires BOTH sensors and averages them to get an output.

It could also be that in removing the ABS functionality from the OP’s bike they did not correctly reconnect the electronics module from the ABS computer; an intermittent connection will kill the speedo/odometer as the data is fed on CANBUS to the instrument cluster.

I also seem to recall there was a TSB (Technical Service Bulletin) regarding the 2005 RT and routing of the front and/or rear speed sensor cables to eliminate the possibility of sensor wire chafing. 

I’ll post the results.


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Last edited by rangemaster728 on Sun Jan 19, 2020 4:24 pm, edited 1 time in total.
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David.
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Re: Speedo Failure

Post by David. »

rangemaster728 wrote:I’ll post the results.
Thank you, if in doubt, do some "field testing". Hopefully, this will clear up the anomaly.
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Speedo Failure

Post by rangemaster728 »

rangemaster728 wrote: OK...

My nephew just brought over his ‘05 RT to roost for the winter.
He’d previously left it in storage for a few years in Arizona and shipped it up to the Pacific NW last year so I did a lot of service work on it to get it roadworthy.

This included oil/filter change, spline lube, flushing the tank and replacing the fuel pump, completely flushing the brakes including the servo ABS system, etc.

The reason I mention this is I now have 2 RTs in the garage...my ‘09 and his ‘05. I’ll use his ‘05 to investigate this as it is has the same braking system computer as the OP.

I’ll fire his up later today and try this test:

1. While on the center stand I’ll jack the front end up, turn on the ignition and spin the front wheel to see if the speedo starts to indicate.
2. I’ll then lower the front wheel (the rear is now off the ground), put the bike in gear and (carefully) advance the throttle to spin the rear wheel and see if the speedo indicates anything.

This will show if the speedo needs just one sensor input to function - and if so, which one is needed.

There is also the possibility (knowing German engineers) that the speedo requires BOTH sensors and averages them to get an output.

It could also be that in removing the ABS functionality from the OP’s bike they did not correctly reconnect the electronics module from the ABS computer; an intermittent connection will kill the speedo/odometer as the data is fed on CANBUS to the instrument cluster.

I also seem to recall there was a TSB (Technical Service Bulletin) regarding the 2005 RT and routing of the front and/or rear speed sensor cables to eliminate the possibility of sensor wire chafing. 

I’ll post the results.


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Just tested this on an ‘05 RT Using the procedure outlined in my previous post.

I stand corrected, speedometer input is apparently from only the rear wheel speed sensor circuit.

No matter how fast I spun the front wheel by itself, there was no deflection in the speedometer. While on the center stand I put the bike in first gear and slowly let out the clutch to rotate the rear wheel. The speedometer functions.

So if the OP has replaced the rear speed sensor, we’re down to one of four things:

1. Problem in the wiring between the speed sensor and the ABS computer.

2. Intermittent connection in the ABS computer.

3. A problem with connection on CANBUS between the ABS computer and the KOMBI module (instrument cluster).

4. Bad instrument cluster.

Since the last thing really done to this bike was disable the ABS, I’d start looking at the electrical connections between the speed sensor and ABS computer, and then the connection from the ABS computer to the KOMBI module.

If it were my bike, I’d remove the bodywork, drain the gas tank and pull the tank, then inspect how the ABS bypass was done. Much easier to sort through that wiring with the gas tank out of the way.

If the person doing the work did not properly reconnect the ABS computer, or somehow left power off of it or it became intermittent, that would cause the symptoms the OP is experiencing.

But that’s just me....


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Last edited by rangemaster728 on Sun Jan 19, 2020 9:38 pm, edited 1 time in total.
Gerbil007
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Re: Speedo Failure

Post by Gerbil007 »

Many thanks all. Bike is heading back to the outfit that de-servo'd the bike for me.
rangemaster728
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Re: Speedo Failure

Post by rangemaster728 »

Excellent!
Please let us know what they find.

Ride safe!


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David.
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Re: Speedo Failure

Post by David. »

Just a thought, I believe that early Hexheads (05-07) had the final drive oil changed at 600 miles, after that, it was there for life, "permanent" not changed.
This was certainly the case with my 2007 model, I remember commenting on how expensive the "permanent" oil was at the time.

This photo shows the rear speed sensor on an 05 GS after only 20K miles.
Image
BMW now recommends a FD oil change every 12K miles.

Although the rear speed sensor has been changed, could dirty/contaminated FD oil cause the sensor not to pick up a signal from inside the FD unit.
The model in question is 2005, has the FD oil been changed since new, what mileage has the bike done now (~40K).

JVB, Final Drive Fluid Service, http://www.jimvonbaden.com/R1200_Final_Drive.html
Last edited by David. on Tue Jan 28, 2020 6:02 pm, edited 1 time in total.
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Re: Speedo Failure

Post by jackronner »

Interesting reading, but when I put on the correct front speed ring on the wheel of my 2009, the dead speedo worked fine and all the ABS warning lights went off. 
Gerbil007
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Re: Speedo Failure

Post by Gerbil007 »

Little update. The bike has gone back to the independent who removed the ABS servo. To cut a long story short, they are baffled. The diagnostics is coming back with all kinds of errors which they believe could indicate either:


1. Moisture ingress to connectors
2. CANBUS / ECU failure.


Really crossing my fingers that its 1. Bike is kept outdoors, which may account for moisture ingress.
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