2011 - R1200r K27 - Code 23971 -Rear Wheel Speed Sensor

[Newportcycle]

I've posted this on the BMWMOA website as well, but knowing there are some here who are not members, I was hoping this maybe an issue others have come across.

So on my way to MOA Rally in Hamburg NY this last July I experienced intermittent ABS lights blinking in the display but after a couple of re-starts these went away and bike performed as expected. Since the rally I've purchased a GS-911 unit and performed a scan of the various computers, the Code 23971 Rear Wheel Speed Sensor : Signal implausible was registered two times, I assumed from the ride to Hamburg. I've since performed a 40km services changing all fluids and the like and on a ride today the ABS lights were again flashing, and the speedometer had stopped working; when I scanned this code popped up again. I removed the rear wheel sensor, cleaned it as I did not remove it during the 40km service, there was a little debris on it but nothing that appeared major. Ive also unplugged the sensor at the computer interface cleaned the contacts with CRC electric cleaner and took it for another ride. The lights would not reset, speedometer in operative, however this time no codes registered with the GS-911. I checked the resistance of the speed sensor at the plug and got 12.35 megohms, I believe this to indicate a faulty sensor. Do folks with more knowledge concur with this or have I possibly missed a vital step in diagnosis?

[deilenberger]

12Mohms seems awfully high for that sensor. I would have to guess you've identified the problem. Is the cable chafed or pinched? It's routed rather oddly so as to avoid hitting the brake rotor, and if it isn't in just the right spot - it can wear through and all the good smoke comes out.

[GBag]

Its poo! Toss it and put a new one in. Mine went around 27,000 mi. R1200R 2011. ABS & Caution Light flashing. Also I lost both my speedo & tach. They dropped like stones. Luckily I had my GPS so speed wasn't an issue. New sensor and all was right. Now at 56,000 mi and still fine.

[Newportcycle]

Thank you for the replies. Don I checked the routing carefully, all the correct cable anchors are in place and no chaffing that I can see, that was the baffling part, also not knowing just what the ohm reading should have been has caused quite a bit of anxiety as I hate to -spend money on replacement parts only to have the issue remaining. It will be here in a couple of days, we will see how it goes.

[deilenberger]

12.35m-Ohms sounds like the default reading of the VOM on an open circuit.. with perhaps a bit of cross-talk between connectors. As a WAG - I'd expect to see less than 15k-Ohms, probably considerably less. A high impedance device for that use would end up working like an antenna - so it would be effected by ambient RF noise...

[sweatmark]

Assuming the K27-spec wheel speed sensor is advancement on the R28 R1150** bikes, the sensor is likely based on dual-differential Hall effect sensor IC, two-wire, current output with self-diagnostic startup. Measuring resistance on the IC has no meaning in terms of sensor function.

[Newportcycle]

Thanks for the additional reply's. Don I was getting open circuit reading on my ohm meter when in automatic mode, I had to switch to manual to get the 12.35m-Ohms reading.

Sweatmark, I've read that there are sensors utilizing an IC and you cannot measure them, and there's part of the rub with me, there is no indication in my Clymer manual as to just WHAT type of sensor is being utilized. I checked voltage and continuity at the plug to the computer and wire was good and 12.99 volts at the pin, which was exactly the same voltage I measured across battery terminals.

The new sensor should be in the mailbox today, I'll get it mounted to night and see what happens.

Thanks all for the reply's.

[Newportcycle]

I've replaced the sensor. ABS and speedometer are now functioning normally.

[deilenberger]

I've replaced the sensor. ABS and speedometer are now functioning normally.

Gave you a thumbs up on the MOA website. It's good when things work.

[Newportcycle]

I've replaced the sensor. ABS and speedometer are now functioning normally.

Gave you a thumbs up on the MOA website. It's good when things work.

Yes it it, thanks for the input, diagnosis and advise is one of the highpoints of the internet.

I was skeptical of the GS-911 and whether or not I really needed one. With the money saved on my 40km service and again to diagnose and repair the rear wheel sensor, near as I can figure I've saved over $350 dollars, this includes the cost of the new tool, which I've got to use again.