ABS fault - pretty usre it's not the battery

[TracyPrier]

Hi guys

 

Need a little help

 

My 2000 r1100rt-p is showing an ABS fault. Here are the specifics so far.

 

When I check the code it is a 7, controller unit.

Haven't cleared and rechecked yet so there may be other fault codes. I'll do that tonight (just read today that only one code is stored at a time).

 

Battery is 12.96 volts at rest. It is a BMW gel battery.

 

The fault appears when I move off and not before. Usually you get the double "dok-dok" noise when you take off. I am only hearing a single "dok" now, and then the fault lights start flashing.

 

That's it to this point.

 

Can someone tell me exactly what the "dok-dok" noise is? I know it is something to do with the ABS system but what exactly is making that noise? I ask because, as I am only hearing a single "dok" now it makes me think something isn't calibrating/setting itself... if that's what the noise indicates and hopefully it may be indicating the cause of the fault.

 

Thanks in advance for any help.

 

Tracy

 

P.S. Been doing a bit more work on the bike and have updated the web site with what I have done. Check it out at www.myr1100rtp.netfirms.com

[ShovelStrokeEd]

The noise you here is the pump/accumulators briefly cycling. There is one for the rear and one for the front. If you are only hearing one and getting a defective control unit error code, you have the problem. I think I would spend a little time under the hood to be sure no electrical connections are at fault before springing for a new unit. Couple of hours taking things apart, spraying with contact cleaner and assembling with a good lubricant can do wonders.

 

As an aside, have the units been bled?

 

BMW specifies a 1 year brake system flush on those units and it can be critically important. You may also wish to perform a thorough brake flush with fluid from a new, sealed can. It just might clear things up.

[sdemeyer]

This is exactly what my bike is doing....

Please let me know if you fugure it out...

 

Thanks,

Scott

[sdemeyer]

Is there any way to force the pump to cycle while the bike is on the center stand ?

[TracyPrier]

Thanks Ed.

 

Hmmm... I had thought that the bleed would have been done at the dealer before I bought it but maybe not...time for a clean up and brake bleed then.

 

I have downloaded instructions for making a resevoir filler funnel (rather than buying the expensive BMW tool. In the instructions they mention a part number for the filler cap (which you drill a hole in and glue a funnel into) but this part number is not valid either at my local BMW dealer or on the A&S Cycles online parts search.

 

Does anyone know the actual part number for this cap or is there something else I can use to do the job?

 

Thanks

Tracy

[bmwmick]

Tracy,

You don't need any fancy funnel, I believe you have ABS-II like all the other R1100RT's.

The noise you are hearing is the ABS clutch mechanism cycling. There is only about 2 tablespoons of brake fluid in each ABS pump reservoir so I doubt that a missed flush is your problem. If you take it to a dealer, I'm betting they call it a "piston fault".

There are two electro-magnetic clutches in the ABS unit. They look a lot like an AC compressor clutch on cars but much smaller. There is a high torque DC motor that drives a main shaft via a worm gear. When the Control unit decides to cycle the ABS, it runs the motor and energizes one of the clutches. This connects the clutch to the main shaft and a link chain is wrapped around the clutch housing. This chain pulls against two VERY strong springs and allows the piston to move slightly(this increases the volume of the . There is a steel shaft on the piston assembly that is moved through a coil when the piston is cycled. The Control unit sees a generated voltage created by that shaft moving through the coil. If the voltage created is not exactly the level it 'thinks' it should be, the Control unit signals a "piston fault".

There are only 8 connections between the Control unit and the mechanical clutch assembbly. You might want to remove the control unit from the side of the ABS unit and check that connector. My guess is that the clutch for either the front or rear ABS circuit has failed, a wire is broken OR the transistors that pick the clutch have failed.

 

Mick

[russell_bynum]

You don't need any fancy funnel, I believe you have ABS-II like all the other R1100RT's.

 

Correct.

[TracyPrier]

Woo hoo !

 

Thanks Mick... that is great info. I'm an ex-car mechanic so am quite happy doing stuff like that... and NOT buying a new controller

[Brian Chandler]

My 2000 RT is doing the same thing. Twice I have reset the fault code )using instruction found elsewhere on this site) and pulled the #5 fuse for at least 10 seconds to get it working again. Resetting the ABS fault alone did not fix it. Of course , you could argue it is not fixed since it has done it twice.

[bigboy]

hi tracy

i aint no real expert but could it be you are hearing the relay cutting in and out is the noise in time with the red lights on the dash board ifso a reset should do it , when this happened on mine i full charged the battery reset the abs and hey presto the battery was to blame although on my meter it was showing a good vaultage.

let us all know how it goes for you.

[Stephen_Chase]

The ABS on my R1100RT occasionally won't come on when starting the bike after it has sat for a week. When I get rolling I don't get the beep-beep and the ABS lite flash alternately. If I re-start it's good for the rest of the day. Any suggestions??

Stephen

[Brian Chandler]

The ABS on my R1100RT occasionally won't come on when starting the bike after it has sat for a week. When I get rolling I don't get the beep-beep and the ABS lite flash alternately. If I re-start it's good for the rest of the day. Any suggestions??

Stephen

 

Sounds like a weak battery.

[ShovelStrokeEd]

Check the clearance at your wheel speed sensors.