ABS III on R1150RT - pump running constantly

[bmwk75c]

Apologies is this is covered in the forum.

I recently bought a 2003 BMW R1150RT with ABS III as a project bike with 71k on the clock

I also own a 2006 R1150R with ABS which is my "fun" bike.

The project bike had been sitting since 2016. Owner disclosed brake issues, he could not be bothered and parked it. I found that the ABS to front wheel circuit was completely dry. I refilled, bled (have the vacuum tools) and brakes are working manually when applied without engine. (PH appears ok, will change the other fluids eventually)

When I power up (ignition to "start"),  what I presume to be the the front ABS motor (there are two inside the ABS unit, with separate motors and  pumps) continues to operate continually and does not stop, kept it going for 30 sec before switching off.(BTW, new battery) I presume that the pump cannot reach correct pressure?

This appears to have been an ongoing issue judging by the amount of "crap" I had to clean of the front wheel, therefore presume excessive pressure which blew out brake fluid to wherever possible.

 

Owning another similar unit I am aware of the standard starting procedure, e.g. ABS pump engages to built pressure, light then  flashes at a lower frequency,  lights do not go off until you move forward....

 

I have checked ABS wheel sensors ( and cleaned them) clearances, they appear to be within range.

Early indications are that the relays in the main fuse box are ok. I have checked the cables and, while the standard german efficiency when it comes to cable tie tension applies (I can say that since I was born there ....)  continuity appears to be in range.

Therefore: 

a) I have never stuffed around with the "factory preset"  pressure sensors on top of the ABS unit,  could theses be the issue? 

Does anybody have any experience in servicing these?

b) while I know the internal components of the ABS III unit I have never pulled one apart, could it be that one of the internal seals has let go? Could the pump part of the servo have failed which means that pressure is not building in the ABS unit? How do I check this?

c) are there any hidden relay locations other than the main unit behind the air filter enclosure as there was in earlier ABS units?

 

What else should i be looking at?

 

Thanks in advance

Richard

[dirtrider]

4 hours ago, bmwk75c said:

Apologies is this is covered in the forum.

I recently bought a 2003 BMW R1150RT with ABS III as a project bike with 71k on the clock

I also own a 2006 R1150R with ABS which is my "fun" bike.

The project bike had been sitting since 2016. Owner disclosed brake issues, he could not be bothered and parked it. I found that the ABS to front wheel circuit was completely dry. I refilled, bled (have the vacuum tools) and brakes are working manually when applied without engine. (PH appears ok, will change the other fluids eventually)

When I power up (ignition to "start"),  what I presume to be the the front ABS motor (there are two inside the ABS unit, with separate motors and  pumps) continues to operate continually and does not stop, kept it going for 30 sec before switching off.(BTW, new battery) I presume that the pump cannot reach correct pressure?

This appears to have been an ongoing issue judging by the amount of "crap" I had to clean of the front wheel, therefore presume excessive pressure which blew out brake fluid to wherever possible.

 

Owning another similar unit I am aware of the standard starting procedure, e.g. ABS pump engages to built pressure, light then  flashes at a lower frequency,  lights do not go off until you move forward....

 

I have checked ABS wheel sensors ( and cleaned them) clearances, they appear to be within range.

Early indications are that the relays in the main fuse box are ok. I have checked the cables and, while the standard german efficiency when it comes to cable tie tension applies (I can say that since I was born there ....)  continuity appears to be in range.

Therefore: 

a) I have never stuffed around with the "factory preset"  pressure sensors on top of the ABS unit,  could theses be the issue? 

Does anybody have any experience in servicing these?

b) while I know the internal components of the ABS III unit I have never pulled one apart, could it be that one of the internal seals has let go? Could the pump part of the servo have failed which means that pressure is not building in the ABS unit? How do I check this?

c) are there any hidden relay locations other than the main unit behind the air filter enclosure as there was in earlier ABS units?

 

What else should i be looking at?

 

Thanks in advance

Richard

 

 

Morning Richard

 

Your BMW I-ABS (wizzy) system doesn't operate as you think it does. The pump(s) don't run until they make a certain pressure then turn off. The pumps  stay off until you  use the brakes, at  that time the pumps start to run open circuit (build no pressure).

 

During actual braking the pumps start running as you squeeze the  front lever or push on the rear pedal, then the lever/or/pedal pressure input  moves internal  control pistons that closes internal control valves in relation to your input pressure.  Those closed control valves then force the open circuit fluid flow to pressurize & that  then pressurizes the wheel circuits & applies the brakes.  (the running pumps are what applies fluid flow to the brake circuits, pedal or lever pressure on internal pistons/valves then causes that pressure to build & operate the brakes)

 

The usual problem with the BMW I-ABS system (assuming the reservoir floats & pedal/lever switches are working)  is a failed internal pressure transducer. Those are not available to buy & a real pain  to install & calibrate even if you could buy one so that isn't a home type job.

 

Tell us EXACTLY what the flashing dash lights are doing as that can help us tell what is going on with the ABS controller (sometimes anyhow).

 

A GS-911 can tell you even more.   

 

The relay in the fuse box has nothing to do with the ABS or brake operation, it is ONLY used to allow the ABS controller to flash the dash light.

 

Those are not pressure sensors on top of the ABS controller, those are fluid level sensors for the reservoirs.

 

Same with wheel sensors,  the brakes (power assist) will work OK without them, you just won't have ABS available.  

 

The place to start your troubleshooting is to verify that both lever & pedal manual switch's are working correctly (you should hear a light click as you move the lever or pedal). Those switches work reverse logic  (are N/C then go open as the lever or pedal is moved). 

 

Your other option (if legal in your county) is to simply remove the ABS system then re-plumb to manual brakes. That part is easy but you also have to add a relay (you can use the existing ABS relay)   to allow the brake lights to work properly then also jumper the tail light circuit (not a big deal to do as you can do it right at the ABS controller connector)