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Rear wheel sensor or what?


MichiganBob

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Hi Everyone. My latest ride is a 2012 1200rt. Loving the bike. Took a trip last weekend -- 800 miles. About 50 miles out, brake failure light came on. I tried different ways to reset it, checked fluids, and just kept on going figuring that I would not have any ABS. Brakes worked fine. Since I've been riding since 1968, I figured I can be fine without ABS. At the same time, noticed that my cruise control and self-cancellation feature of my signal lights was not working. Then during the trip, found that my speedometer does not start working until I'm 10-15 minutes down the road. Then it starts up and works fine. Not sure if these four issues are connected or not. I'm thinking that the brake failure light, cruise, and cancellation is the rear wheel sensor and the speedometer is a front wheel sensor. It seems unusual that two sensors would go at the same time. So, any thoughts on this. If a rear wheel sensor, any advise on how it is changed. I'm not sure what it looks like when it enters the rear drive housing so I want to be careful about doing any yanking on it.

 

Your insights, as always, is appreciated.

 

MichiganBob

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Actually, the speedometer signal comes from the rear wheel speed sensor, so that one component could cause all your problems.

 

Jim von Baden has a pictorial on changing FD oil here. Step 4 has several good pictures showing the speed sensor location. I think your bike has the wire routed a little differently than the '07 model shown, but it should be very similar otherwise. I'd start by examining the wire for pinches, scrapes and cuts, then make sure the connection to the wire harness is making good contact.

Edited by lkraus
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Morning Bob

 

It does kind of point towards the rear wheel sensor (chafed pig tail or lots of metallic crud on the sensor itself).

 

The rear sensor is not too bad to access-- Just remove rear muffler attachment, loosen the front attachment, then swing muffler out away from the rear tire, then remove rear wheel. At this time the rear sensor is easily accessible.

 

Your problem might be as easy as the sensor is packed with metallic particles so it can't pick up the speed reading correctly.

 

The good news is that metallic particles are easy to remove, the bad news is that can/or/usually points to a failing final drive.

 

If you remove that sensor for inspection just be VERY careful to not nick the "O" ring at re-installation.

 

2011%20final%20drive_zpscxbjmhgo.jpg

 

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Morning Bob

 

You can give it sort of a quick test by putting the bike on the center stand & in neutral, then turning the key on (do not start engine), then spinning the rear wheel with your foot (or have someone else spin rear wheel), then simply pulling the front brake lever.

 

If the rear wheel locks up quickly when you pull the front brake lever that means that the rear wheel sensor is working (at least at that point in time)

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Afternoon Bob

 

Actually you can still have linking from front lever with no ABS working (but not with a failed rear wheel sensor)

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A crisp Fall Michigan afternoon to you DR. Yup, no effect on rear wheel with key on and front brake lever engaged. I will pull muffler and wheel and check the wiring harness for any visible defects. If none found, pull the sensor and check for metal or other residue, and go from there. I'll get back to folks about this so they can make a mental note if they experience similar issues. That's what makes this board so valuable.

 

Be well.

 

Bob

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Good Afternoon. The wires seem fine (at least from the driveshaft housing back. Pulled sensor. I suppose there should be a little rear end oil on it thus the 0-ring. Nothing remarkable on the sensor. No filings. Will wipe clean and reinstall with a hope and a prayer.

 

Bob

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Afternoon Bob

 

If you can get to the rear wheel speed connector you might measure it's resistance across the 2 pins.

 

I have the (will work) resistance somewhere but for some reason I can't seem to find it at the moment (I might also have it written down in my shop somewhere but I'm no where near that at the moment)

 

In any case I would imagine that the resistance should be somewhere in the 1k-2k area. If it is open or shorted then your sensor definitely has an issue.

 

 

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Afternoon Bob

 

One more thought--

 

Even though technically the speedometer reads off the rear wheel the ABS system might still have to process both ends to allow the thing to work correctly.

 

It's possible that you have a shorted or compromised front sensor problem causing the ABS controller to not allow either end to work.

 

So make darn sure that the front wheel speed sensor is not shorted to the front brake rotor or otherwise compromised.

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I'll give that a try DR. I expect that it is somewhere behind the right Tupperware. At the least, this gives me a chance to become more familiar with this bike. I've only had it a short time so I want to learn more about it. Thanks for your help. And the Lions won. What a day.

 

Bob

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Eyeballed front sensor. Seems appropriately gapped, clean, and intact. I'll try to find it's connector this week and check the resistance.

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Good Afternoon,

 

Any ideas on where the connectors are for the rear and front wheel sensors. It might save me some time in removing everything.

 

Thanks.

 

Bob

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Good Afternoon,

 

Any ideas on where the connectors are for the rear and front wheel sensors. It might save me some time in removing everything.

 

 

Morning Bob

 

I can't remember replacing a wheel sensor on the Camhead bike. If similar to a Hexhead the rear connector should be somewhere around the R/H side near the rear shock area. Front will probably need the R/H Tupperware removed & then glove box or radio box removed.

 

 

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Good Morning DR, Looks like Saturday before I can get to it. Did you say that you had some data on the ohms I should find between the plug pins?

 

Thanks.

 

MichiganBob

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Good Evening,

 

Was talking to the service manager at the Beemer shop. He mentioned that there is a recall (ready for this .. aka "an open campaign") on the multifunction switches. He said bring it in for the upgrade ... perhaps that is why you are having all the issues (brake failure light, no cruise, no turn signal cancellation, erratic speedometer). I'm not seeing it. I will be interested in the outcome of checking the resistance on the wheel sensors this weekend.

 

Bob

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Morning Bob

 

I have seen a large number of those failing or failed handlebar switches & they definitely can cause the cruise control to malfunction or turn signal cancellation issues but I don't see how they could cause a brake system failure or the speedometer to quit.

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  • 2 weeks later...

Good Evening.

 

I finally found some time to check the rear wheel sensor.Take note folks if you are looking for the plugin, remove the battery and it is on the right side cable tied to the frame. I'm not very good on the multimeter but when turned on and set to ohms, it reads 1 and when i touch the two probes, it goes to zero. In all ohm ranges, the number never changed from 1. So i'm thinking that the sensor circuit is open and the sensor is not good.

 

Now the conundrum, do I take my chances and get a new sensor or should i bring the bike to the dealer and have them run a diagnostic? What would you do?

 

Thanks,

 

Bob

 

Bob

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Good Evening.

 

I finally found some time to check the rear wheel sensor.Take note folks if you are looking for the plugin, remove the battery and it is on the right side cable tied to the frame. I'm not very good on the multimeter but when turned on and set to ohms, it reads 1 and when i touch the two probes, it goes to zero. In all ohm ranges, the number never changed from 1. So i'm thinking that the sensor circuit is open and the sensor is not good.

 

Now the conundrum, do I take my chances and get a new sensor or should i bring the bike to the dealer and have them run a diagnostic? What would you do?

 

 

Evening Bob

 

Well it sure looks like your rear wheel sensor has an open in it.

 

A new rear sensor is a little over $200.00 so (personally) I would probably remove the failed sensor then hook my ohmmeter up to the terminals & wiggle/work the wire pig tail to see if I could find the bad area (they are reparable with the proper procedure).

 

Or, not finding the problem, or not wanting to repair, I would probably buy a used sensor from E-Bay for around $40.00-$60.00 (some weeks there will 2 or 3 for sale & other weeks none at all)

 

You can have the dealer look it over but if your sensor is showing open then they will probably charge you good money to tell you what you already know--the rear sensor is bad.

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Good evening DR. Nothing to lose checking the wire. Do you happen to know what else is in a sensor that might fail? A switch? Resistor? Diode?

 

These ebay sensors .. why so cheap? Reputable sources? Curious .. can't recall purchasing an electric component on ebay.

 

Thanks

 

Bob

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Morning Bob

 

On the BMW 1200RT system it uses a basic simple passive wheel speed sensor. (non powered)

 

This is basically a wire coiled around a small permanent magnet with that coil of wire hooked to two pigtail wires long enough to reach the plug-in point. (really not much to them at all)

 

The usual cause of failure is:

 

The permanent magnet plugs up with metallic debris stuck to the magnet.

 

The air gap of the sensor to the toothed reluctor wheel opens up for some reason.

 

The wire coil or wire pigtail goes shorted.

 

The wire coil itself, or the pigtail wire, goes open (ie cut or pulled/stretched apart). With your infinity reading this seems to be your present issue.

 

As for E-Bay sensors being cheaper?-- they are used parts (supposedly came off a functioning motorcycle) so used parts are usually cheaper. You just have to deal with a reputable seller that will replace it or refund your money if they send you a bad one. In most cases E-Bay will refund you directly if the seller won't.

 

Over the years I have actually had very little problems with used E-Bay motorcycle parts as long as the seller has a decent rating & has been selling on E-Bay for a while.

 

The very few issues that I have had over the years were either refunded promptly back to my Pay Pal, or quickly replaced by the seller, on a couple I had to use the E-Bay protection so E-Bay refunded my money back into my Pay Pal account.

 

If buying a wheel sensor on E-Bay just ask the seller IF the sensor wire has any nicks or cuts in it. You might also ask if they will measure the resistance before sending (some sellers might some sellers won't)--In any case if they tell you no nicks or cuts & it comes with a damaged pigtail then have them make it right or issue a refund.

 

 

 

 

 

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Good Morning DR,

 

I appreciate your anatomy of the sensor -- it makes perfect sense. A while ago, you mentioned having the resistance numbers somewhere in the shop. As time allows, please forward. I have a lead on a used one for fifty bucks. I will ask them to check the resistance before I purchase. Stay tuned.

 

One other thing, you mentioned a failure due to the gap widening. Would that only pertain to the sensor on the front wheel? I see where there is a gap on the front wheel but it seems that the rear sensor does not gap as it is mated to the rear housing and affixed with a small screw.

 

Bob

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Good Morning DR,

 

I appreciate your anatomy of the sensor -- it makes perfect sense. A while ago, you mentioned having the resistance numbers somewhere in the shop. As time allows, please forward. I have a lead on a used one for fifty bucks. I will ask them to check the resistance before I purchase. Stay tuned.

 

One other thing, you mentioned a failure due to the gap widening. Would that only pertain to the sensor on the front wheel? I see where there is a gap on the front wheel but it seems that the rear sensor does not gap as it is mated to the rear housing and affixed with a small screw.

 

 

Morning Bob

 

I did take a quick look for that resistance & couldn't easily find it (I'm sure I have it written down somewhere just not sure where)--If/when I find it I will send it to you.

 

 

The gap can widen on both the front & rear, the front is obvious due to worn wheel bearings or bent tone ring. The rear can be from bad bearing or bearings in the final drive as that can cause the spool to move sideways.

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I've had the exact same issue a couple times in the past. The most recent after having my tires changed. I pulled the rear sensor, cleaned it off and double checked the cable was in good condition and routed correctly. I was unable to pull the front sensor, but cleaned it up as best I could. I also cut the cable-tie at the brake line joint above the fender where the cable takes an abrupt 90. The issue resolved itself shortly thereafter.

 

As they say: YMMV

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Good Morning,

 

Here's the update. Since the rear wheel sensor has no ohm resistance, I decided to change it. Found a site that has four used sensors. I asked them to test them for resistance and they said they would and get back to me. Stay tuned. I'm hoping to say that I replaced the sensor and it took care of all four problems: brake failure light, no cruise, turn signals not self-cancelling, and speedometer not working until 5-10 miles down the road. We'll see. If not, I'll simply move on to the next challenge.

 

On another note, I'm reading an adventure biography called "Ghost Rider" by Neil Peart. He was the drummer for Rush who lost his wife and daughter in the same year so took of on his GS and rode thousands of miles from Quebec to Alaska all the way down to Patagonia. Very enjoyable read and you can find a used copy pretty inexpensive on Amazon.

 

Bob

 

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  • 3 weeks later...

Long time Rush fan here. He also rode between shows on all their tours for the last 15 years. If you like his writing style there are several more books about his continued adventures. I know many of us on here are well versed in the writings of the Professor.

Edited by Hammock Mike
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  • 3 weeks later...

Good Evening,

 

Wanted to give everyone an update. Finally able to get the rear wheel sensor changed and just went out for a test ride. It was interesting to see a snowflake and the 32 degree notice blinking. To review, this is a 2012 1200rt. I had a brake failure light that stayed on, no cruise control, signal lights were not self-cancelling, and the speedometer was erratic (taking about ten miles/minutes before it started working).

 

Conferred with the folks here on the board and we agreed that all of these failures occurring at the same time is likely to be the rear wheel sensor. My dealer thought they can get me out the door with a new sensor for about 300 dollars. I thought I would first try a good used one. Found one on a site called Beemer Bits in Tucson and spoke to JD. He agreed to test one to make sure it worked before sending it. Priced about a third less than a new one by the way.

 

Finally got the bike out on the road today and everything is working. Hooray.

 

Changing the sensor is easy. Pull rear wheel and sensor. Take off bottom part of rear flap and the cable/brake line protector on the frame. Snip a few ties, pull the seat and the battery and swap them out.

 

That's the story. Thanks to everyone who helped me out on this.

 

Take good care and happy holidays.

 

Bob

 

 

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Morning Bob

 

Thanks for the follow up-- glad it is now up & working for you. (just in time for the snow storm coming your way!)

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I bought two sensors off Ebay for $50. They said they were same as RT, but when they showed up they were the kind with the valve stem through them, not the independent screw in type. After a couple of days thinking about it, I removed the valve stem and drilled out a hole, mounted them up, replaced tire and synced with GS911 (after coping down the sy #) worked like a charm. $50!!

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Bob,I think you are talking about tire pressure sensors, mounted on the wheel. The problem here was the rear wheel speed sensor, which mounts in the final drive.

Edited by lkraus
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