[Nitsuj]

Hi all, I'm new here. This site was reccomended to me by a gentleman helping me diagnose this issue on another forum, he suggested that I run it by you gents.

Here's the story. A friend brought me his 2006 R1200RT with 76k miles because it the dealer told him it needed a final drive, among other things. From time to time, his brake failure light would blink, the red triangle would blink and the speedo would stop working. He took it to a dealer and they told him they found several faults. Low fluid level, low voltage, and low rear pads. The tech also wrote in the comments section that the ABS pump may need replaced if the above doesn't fix the codes. When removing the rear wheel, the tech also noticed a large amount of play in the final drive.

So, for reasons I won't go into to, my friend doesn't trust this dealer so he brought the bike to me. Final drive had tons of play, so I confirmed what the dealer told him. I replaced the final drive with a known good unit from a 2005 1200GS, George from Beemer Über Alles advised me that the final drive would work other than the gearing being lower. A visual inspection seems to confirm this, as both final drives appear to have the same indicator ring when viewed and measured through the sensor hole.

So new final drive installed, new brake pads, still have the failure light and triangle blinking. Except now it does it all the time and not just sometimes. (battery is 100% charged) So, I stripped the bike, and did a complete brake fluid flush and bleed according to the instructions found in this article http://advwisdom.hogranch.com/Wisdom/service_abs3.pdf

Now, I don't have a red triangle anymore, but the failure light is still blinking, and the speedo doesn't work.

I'm trying to eliminate as many possibilities as I can before telling this guy to order a new ABS pump.

Any ideas? Thanks in advance!

 

[hopz]

First... is the brake warning light and message occurring when you turn the key on? If so it is supposed to do that.

Then I have to ask if you are aware that the bike must move at least 10 meters or so before the Brake Failure notice turns it self off? This is the calibration step to be sure the system is actually functioning.

If you are aware of all this then I suggest you start by a very close and detailed check of the ABS sensor position down on the clutch side of the front wheel.

That ABS sensor itself can get out of alignment fairly easily if someone removes the wheel without being aware of the possibility of dislodging the sensor from its intended location... especially when re-installing the wheel. By the way, I find it curious that the rear pads were worn... but no comment about the front pads. Maybe someone replaced the fronts- since that is where most of the braking force comes from. To do this they would have to remove the front wheel or at least the calipers. Therefore the opportunity to not get the ABS sensor back correctly is a possible cause. A bike with 70k miles or so would likely have signs of wear on the rear pads... again normal and just about the expected life of the rear pads.

Next, carefully inspect the sensor wire itself all the way up the fork tube. Some bikes had a problem in this area and the ABS wire's insulation was wearing off due to the path the wire takes. There was a tech bulletin about this, and while not a "recall" it was alerted as a point of inspection. You just need to be certain there is no damage and that the routing position of the wire is out of harm's way.

After these fairly simple inspections you might want the fault codes to be read/reset... if you have a code reader (GS-911) it will be possible. Otherwise it looks like a trip to the dealer.

By the way... the Low Fluid level is normal if the pads are worn. This is fundamental. As the pads get thin the fluid goes down. Often times people fill the reservoir up then later replace the pads and then they wonder why the fluid is leaking out. Duh.

Welcome on board. If you are a friend with a lot of experience with BMW's... that is a good thing but be careful if you have only a little experience with them. This bike has a lot of interrelated and integrated electronics that may or may not be obvious to a person not familiar with the bike.

Also... just throwing a new or rebuilt ABS pump in, is an expensive shot in the dark. You might ask of the owner if the brake fluid has ever been flushed and renewed. If not, it is likely that that moisture has entered the system and corrosion has resulted. This flush and refresh ought to happen every 12k miles. If proper maintenance has not been followed he may actually need the pump. It is a pay me now, or pay me later thing.

Please let us hear how it goes.

 

[beech]

The advice above is really helpful and covers good points. The front wire wearing through, just ran across a bike two weeks ago with that. Devil in the details. Here is a place that repairs modules if it comes to it.

http://modulemaster.com/store/categories/Motorcycle-Modules/BMW-ABS-Modules/

Much cheaper than a new one. In addition to what is offered here I also suggest you do a search on http://www.i-bmw.com/ and the sports touring RT site, http://bmwsporttouring.com/ubbthreads/ubbthreads.php . A ton of information that will take hours to read.

 

[Nitsuj]

I should have been more clear. Yes, I'm aware that the light is supposed to be on until the bike starts moving. The problem is, even after riding a mile, the light is still blinking. I looked at the wire to the front sensor, and saw no signs of damage. I didnt reme or change anything on the front. I'll check out the front sensor again, up until now, I've been concentrating on the rear end and I'll tell you why:

Bike was showing brake fault intermittently until the put a GS rear end and new brake pads on it. Then it was constant. Brake failure blinking, red triangle, and no speedo. Did a full front and rear brake flush, now red triangle is gone, but brake failure is still blinking, only at a slower rate now.

So I've been working under the assumption that something I've done on the back of the bike has changed something.

And since you asked, my BMW experience is limited. I've spent most of my adult life in the motorcycle industry and spent several years as a tech. I know my way around a bike and I'm well equipped as far as tools go. But I've not done much to Beemers. I own an 1150GS, so I'm not adverse to working on them and learning as I go.

To be clear, the final drive I'm using on this 2006 RT came from a 2005 servo ABS equipped GS. If you can think of any reason those 2 drives are not interchangeable, let me know.

 

[hopz]

The GS final drive is compatible as far as I know. In fact, I have heard of several guys who have gone with the GS final drive because of the lower gear ratio.

If I had one available I'd probably change my RT to GS in hearbeat.

If you changed the final drive you also had to remove and then re-install the rear ABS sensor. It is fairly easy to do this but if it did not get back home... it might be hollering at you.

 

[kellenbenz]

Question guys.....does the combination of speedometer not working with ABS warning lead to the rear abs sensor on the RT? I know it does on the LT.

What about the wire leading to it?

I would wonder if a different gear ratio would make a problem through the computer for the speedometer also.

 

[hopz]

This question (post) has let me to search around a bit.

A simple Google search suggests that if you have the ABS light and a speedo problem then look to the rear wheel. The ABS sensor and wire is the starting point.

I was also thinking about my earlier post... about putting the GS final drive on. Two things... this might not be as simple as we thought, and two, did you actually remove the rear wheel, then the ABS sensor and other hardware that mounts to or around the final drive?

If you did remove the ABS sensor (which you obviously must have done), did you put it back? Is the sensor mounting position the same on a GS final drive as on an RT? Is the O-ring clean and in good shape? Is the wire in good shape all the way from the final drive forward? Is the Sensor ring the same on both bikes? Same number of "holes" on the ring etc?

I think the two things are related and am beginning to think the drive swap is not as straightforward as we thought.

 

[Nitsuj]

This question (post) has let me to search around a bit.

A simple Google search suggests that if you have the ABS light and a speedo problem then look to the rear wheel. The ABS sensor and wire is the starting point.

I was also thinking about my earlier post... about putting the GS final drive on. Two things... this might not be as simple as we thought, and two, did you actually remove the rear wheel, then the ABS sensor and other hardware that mounts to or around the final drive?

If you did remove the ABS sensor (which you obviously must have done), did you put it back? Is the sensor mounting position the same on a GS final drive as on an RT? Is the O-ring clean and in good shape? Is the wire in good shape all the way from the final drive forward? Is the Sensor ring the same on both bikes? Same number of "holes" on the ring etc?

I think the two things are related and am beginning to think the drive swap is not as straightforward as we thought.

Near as I can tell, the sensor ring is the same. It's hard to count holes because the mounting point for the wheel and rotor obscure the sensor hole part of the time, so you can only count in 2-3 inch spaces. The holes "look" the same, and by using a set of calipers set center to center on the holes, they seem to be spaced the same. I've checked and rechecked my mounting of the ABS sensor, cleaned the o-ring, etc. I'm fairly certain I have it in correctly. I can see no visible damage to the wire anywhere along it's run.

What I can't get past is the subtle changes my actions have made to the fault. I feel like it's trying to tell me something. Right after installing the new final drive, ABS would initialize and function for a few hundred yards. Then it would flash the "brake failure" and red triangle. So, after seeing the print out from the dealer that listed the faults, I did the ABS flush and bleed. And kept the battery on trickle charge for a few days. After the brake flush, the "brake failure" light starts blinking right away, but at a slower rate, and the red triangle doesn't come on. And this starts right from go, it doesn't run a few hundred yards now before throwing the fault. It seems to me, if the final drive I installed isnt compatible, I'd get a fault right from the get go, and nothing I do would change it. Plus, I was referred to George at Beemer Über Alles, he has a pretty good reputation and he seemed certain the final drive swap would work.

The bike did have the intermittent ABS fault and speedo failure before the final drive swap, so it's not right out of the the blue. But it was after the swap that the fault seemed constant. I feel like I close, but not quite there.

 

[hopz]

I agree with you. This mysteriouser and mysteriouser...

Sounds like you have done everything logical.

I really would like to hear how it goes. Please keep us in the loop.

For some reason I think the ultimate solution will be found to be one of two general possibilities ... One is something really trivial and simple. Two, something fundamental and large such as the final drives are not compatible and the computer is throwing a hissy-fit.

 

[beech]

How about tracing the rear ABS sensor to its first connector, should not be too far. Clip on a device you can measure AC voltage with. Now with the bike on the center stand start up and moderately spin the rear wheel. You should get a couple of volts AC generated by the sensor. This will show one way or another if the sensor is doing its job.

 

[Nitsuj]

Thanks Beech, I'll try that. I was actually considering setting the meter measure resistance and see if it changed as I spun the wheel. I didn't realize it would create voltage.

Guys, keep the suggestions coming. I need to get this thing fixed!

 

[Nitsuj]

Related question... Does BMW offer any of the parts inside the final drive separately? I'm looking at the fiche trying to see if the 2 sensor rings are the same part number, but they only show the whole final drive as an assembly, not the internal parts. Am I missing something?

 

[Nitsuj]

This question (post) has let me to search around a bit.

A simple Google search suggests that if you have the ABS light and a speedo problem then look to the rear wheel. The ABS sensor and wire is the starting point.

I was also thinking about my earlier post... about putting the GS final drive on. Two things... this might not be as simple as we thought, and two, did you actually remove the rear wheel, then the ABS sensor and other hardware that mounts to or around the final drive?

If you did remove the ABS sensor (which you obviously must have done), did you put it back? Is the sensor mounting position the same on a GS final drive as on an RT? Is the O-ring clean and in good shape? Is the wire in good shape all the way from the final drive forward? Is the Sensor ring the same on both bikes? Same number of "holes" on the ring etc?

I think the two things are related and am beginning to think the drive swap is not as straightforward as we thought.

One more thing I forgot, according to Beemer Über Alles, no, the lack of speedo doesn't point to the rear. Apparently, on bike with both the front and rear sensor, like the RT, the computer is taking both wheels speeds and averaging them. So either sensor not working could a speedo failure.

 

[beech]

Related question... Does BMW offer any of the parts inside the final drive separately? I'm looking at the fiche trying to see if the 2 sensor rings are the same part number, but they only show the whole final drive as an assembly, not the internal parts. Am I missing something?

Doesn't the sensor feed off the large gear in there? Can't imagine installing a separate ring in there.
Also, on the abs pick up sensors, continuity is a nice measurement to take along with conductor to ground, but I also like to see the ac output, most of the ones I have worked with in the past had actual ac output specs but bmw probably is not forthcoming on that. If by some chance you found the part from the original manufacturer then specs would be available. Might check for metallic fuzz on the sensor tip. This cuts down on the signal output. I hope it is something simple.

 

[Nitsuj]

I may have had a eureka moment. I got to thinking that being as the rear wheel had so much play, maybe the sensor ring contacted the sensor, but it wouldn't have done obvious damage. I didn't see any signs of damage when I looked it it, but I was looking for obvious signs of being hammered. But it stands to reason, the ring would have just ground it off, like a sanding disc. So off comes the wheel, again, and out comes the sensor. This time, I looked hard under bright light, and compared it to another sensor. It's slight, and I couldn't see it until I really lit it up, but it has been ground a bit. To the point that the integrity has been compromised and oil got it, it weeps oil out of a small hole in the end. So, the sensor has to be bad. It's more obvious in the picture than it is in real life due to the bright flash I used for a close up picture. Crossing my fingers that I can get a sensor quickly enough so I can see if it's fixed and get the bike back to its owner for the weekend.

 

[hopz]

I'm going to Vote... "Bingo" on this one.

The locating and then changing the part ought to be fun, but I'm not sure I'd count on it happening before this weekend unless you get lucky.

Thanks for the photos.

 

[Nitsuj]

I'm going to Vote... "Bingo" on this one.

The locating and then changing the part ought to be fun, but I'm not sure I'd count on it happening before this weekend unless you get lucky.

Thanks for the photos.

Part is due to be here tomorrow AM thanks to the excellent service at Max BMW. I'll put it on in the afternoon and hopefully get in a test ride before evening.

Will installing the new sensor fix it, assuming the sensor is the problem, or will the computer need reset somehow?

 

[kellenbenz]

Not 100 % sure but those that have had wire problems to the sensor have just repaired the wire and once the sensor was working correctly nothing else was needed.

Please let us know how the test ride comes out.

Ron

 

[Nitsuj]

Part got here at 9:30am. Got home from work at 3 put the sensor on, put all the plastic back on and just took a short test ride. All seems well.

 

[kellenbenz]

Congrats on completing a hard fix.

I hope you get to enjoy along test ride.

Ron