2009 R1200GSA odd ABS behaviour

[CandyMan_ZA]

Calling all the gurus out there.

I have a most peculiar behavior on my 2009 R1200GS Adventure. My ABS deactivates randomly. When this happens initially it was only the front ABS, the rear wheel still had ABS. But since last weekend it is now deactivating on both front and rear wheels. The ABS warning light comes on. Other symptoms are the indicators no longer self cancel as well as the moment the ABS cancels and the light comes on the engine does a split second misfire, this is not always noticeable but it happens.

I have pulled and prodded all the wires and cables under the handlebars while riding in the hopes it was something loose or shorting out.

I have managed to replicate it. In the video below you can see (albeit a bit shaky) that the ABS light comes on. I pulled away in first gear, all normal, then with a quick twist of the throttle, not enough to wheelie or even unlikely to cause the Traction Control to kick in, the warning light comes on. I did the same thing again in second gear. This can be repeated in succession with 100% reliability.

I have checked the battery terminals, nothing is loose.

I have been to my BMW dealer where they extracted the error codes, there are ABS voltage and speed sensor warnings present. It is booked in for Thursday but I fear the worst, the dreaded ABS booster pump

https://youtu.be/pV1OcZFVcPg

Any suggestions?

Kevin

 

[duckspeed]

I wonder if you might have a lose/poor earth somewhere

 

[CandyMan_ZA]

I can also add,

if I manually deactivate the ABS the symptoms still display as described above but only when I completely deactivate the Traction Control does the symptoms no longer display ie. on a fast acceleration the ABS light does not come on and the ABS deactivated.

 

[Bendy toy]

The speedo sender uint in the final drive also works with the ABS and traction systems. Check the sender and its wiring are ok.

The front ABS has a separate pickup/sender but the wire is often clipped too tight to the frame so can fail. And the ABS sensor itself can fail.

If they are all ok you are probably looking at worn brushes in the ABS motor under the fuel tank.

 

[CandyMan_ZA]

I inspected the ABS senders, I cannot see anything obviously faulty, the rear sender had metal filings stuck to it so thought ahaa but alas after cleaning it the symptoms are the same.
https://www.dropbox.com/s/620a5rb3dw8n8p9/20160503_180528.jpg?dl=0

 

[CandyMan_ZA]

Here is a single shoot video clip where you can see the behaviour with ABS on/off and ASC on/off.

 

[Bendy toy]

I inspected the ABS senders, I cannot see anything obviously faulty, the rear sender had metal filings stuck to it so thought ahaa but alas after cleaning it the symptoms are the same.

Change the final drive oil and check the lateral play at the wheel rim. It wont fix the ABS, but least you'll clean out the debris.

The sensors are solid state so just looking wont show much. If the connector are clean, the only sure test is with a GS-911

The ABS motor can be removed from the block and have it's brushes changed. There are "How To" vids on You Tube and cost is minimal.

 

[CandyMan_ZA]

Bike still with BMW Dealership, they want to first replace the rear wheel bearings and diff oil and see if the ABS is then still an issue. I will update when I know more.

 

[Bendy toy]

New wheel bearing is fine but what about the internal bearings. They are unlikely to be in a better state.

If you are paying the bills you will get the whole FD overhauled by Mikeyboy for less than BMW will want for the wheel bearing alone.

There is also a simple test. Change the FD oil. Replace the speedo sensor and see if it works (BMW will have used spares they can try). Any wear issues inside the case will take time to clog the sensor so it either works or it does not work. If it's the latter (likely) they need to look elsewhere.

 

[CandyMan_ZA]

The ABS issue has been resolved. It turned out to be a wire that the after market battery had chaffed through, no cost to repair

 

[Bendy toy]

Don't blame the battery. Wires getting chafed in that support channel alongside the battery case are very common with or without an aftermarket battery. I've seen one rubbed right though to the copper.