ABS/Speedo Warning Light Fault – How I fixed the problem.

[mikeey]

I have a R1200 GSA 2010 model with ABS.
Recently I started the bike and the Brake Failure red warning light check flashed on the instrument panel as usual and went out shortly after moving off. A short time later the warning light came back on for no apparent reason. I checked the brakes and they appeared to be working normally. The following day I took the bike out and the warning light came back on, but this time, the speedo stopped working. I then carried out the following checks.

Made sure that the front and rear brake levers were working properly.
Checked that the rear brake light was working.
Checked that the brake fluid reservoirs were topped up.
Checked the battery voltage with a mutimeter.
Checked that the front ABS sensor and rear ABS\Speedo sensor cables were not damaged.
All appeared to be OK.

I then got hold of a GS 911 diagnostic tool and found two fault codes

Integral ABS 2-Can
23969 and 23971: Rear wheel speedo sensor: signal implausible. The fault is not present now.
I reset the code faults but the fault occurred again after a short ride on the bike.

I then removed the rear wheel and took out the rear ABS\Speedo sensor on the Final Drive housing. The sensor head was covered in emulsified Final Drive oil. The rubber O-Ring seal on the sensor appeared to be damaged and may have been the cause for the water ingress. To be honest, it could have been caused by the power washer I used to clean the bike (not any more).I replaced the sensor O-Ring seal and drained the water contaminated axle oil (grey in colour).I replaced the axle oil (180ml) via the sensor plug hole and turned the rear wheel several times before draining the oil once again. It was still slightly contaminated. I then filled the Final Drive with fresh oil (Castrol Syntrax 75W-90) and replaced the O-Ring seal on the drain plug. After that I plugged in the GS 911 to reset the fault codes.The problem is now resolved. The brake failure warning light no longer comes on and the speedo is working. The GS 911 indicates that the ABS is functioning properly. I will change the Final Drive oil again after 100 miles to make sure I have flushed out all traces of water\moisture.

 

[andy79]

Well done good job. I need to get myself a gs911 tool.

 

[Pukmeister]

Glad you fixed it and thanks for the solution.

I recently changed my emulsified oil in my final drive, probably caused during riding through flood water a month or so ago. At no point have I had ABS warning lights because of it. The oil was more of a creamy caramel or milky coffee colour than grey. I presume yours was very emulsified??

Did you inspect the ABS sensor itself for cracks or damage?

 

[Deleted account 190920001]

The speed sensor usually throws errors because it gets furred up with fine metal particles, worn FD bearings usually. I am surprised that emulsified oil no matter how bad stopped it working since it works via magnetism. Result for you either way.

 

[mikeey]

Reply to Pukmeister

Hi, The oil was seriously contaminated with water and had been like that for some time.I was lucky it did not cause some serious damage.I checked the sensor to make sure it was properly sealed.There was no signs of damage.I think the thin metal washer cut into the O-Ring seal positioned in front of it when the sensor was secured in place.It was overtightened.Definitely not the recommended 4Nm.

 

[mikeey]

The speed sensor usually throws errors because it gets furred up with fine metal particles, worn FD bearings usually. I am surprised that emulsified oil no matter how bad stopped it working since it works via magnetism. Result for you either way.

I take your point.I can only confirm the problem persisted over a period of a few days.Initially I took the sensor out and inspected it.It was clear of metal deposits and showed no signs of damage.At this time, I did not replace the seriously contaminated oil and the problem persisted even when I reset the fault codes.However, as soon as I replaced the emulsified oil the problem was resolved.I could see that there is a sensor ring which is an integral part of the gear assembly,inside the Final Drive housing.The rear sensor is positioned a few millimetres from the rotating ring and I presume reads the pulses between it and the ring through an AC magnetic induced current when the wheel turns.Maybe the fact it was submerged in a pool of water with a splash of oil interfered with the sensors ability to read this information.As you say, it seems odd bearing in mind the sensor is a sealed unit, but it worked for me.