Servo / ABS Problem R1150RT 2003

[AndyS]

Hello one and all.

I have a brake problem which shows itself in different ways. I am hoping for some help with.

So here are the assorted symptoms:

 

1/. Sometimes all OK. ie switch ign on. Idiot light illuminate. General warning light on, Failure light flashes fast. Servo motor chirps, General light extinguishes, Failure light flashes slow. Ride away and Failure light goes out.

 

2/. Sometimes as above 1/. but then after an unpredetemined time the Failure light starts flashing fast. I check front lever - Brakes work good, push the rear lever - Brakes work good.

 

3/. Sometimes as above 1/ then again at a random time BOTH the Geneal warning light illuminates steady AND the Fault light flashing fast. I check front lever - Brakes work good, push the rear lever - Brakes work good.

 

4/. Sometimes I switch ignition on and Servo does not chirp, Fault light flashes fast and Servo does not work at all. I check front lever - Brakes BAD (residual), push the rear lever - Brakes BAD (residual).

 

 

5/. Sometimes I turn ignition on, Servo chirps, fault light flashes fast, when I rede away fault light keeps flashing fast BUT I check front lever - Brakes work good, push the rear lever - Brakes work good.

 

Diagnosis:

Checked resevoirs at handlebar - level good

Checked resevoir at pedal - level good

Checked levels on Servo unit - levels good

Checked level switches on Servo unit - continuity across switches - good.

Check rear bulb is OK - good...replace it anyway!

Check brake pedal microswitch - good

Check battery with load test - good

Check front and rear ABS sensors with them disconnected (measuring at the tails) - Multimeter reads 10Mohm(???!!) I don't know what to expect, but I did expect less than this.

 

Now later on when everything was nicely back together something stange happened...I had igniton on looking for stuff. and while I was not touching anything the Servo motor started up on it's own and would not stop. At the same time the Brake light illuminated. While it was running I pull on both levers and the servo seems to load up according to lever pressure.

While it is still running I check the brake pedal switch - no change.

 

So I am a little stumped. Any thoughts???

 

 

Andy

 

[Dave Faria]

I think Britian salts the roads in the winter. I would 1st check the micro switch in the foot brake and then the hand brake to see if they could be intermitten.

[Boffin]

The only thing you seemed to have left off the list is the front brake switch - in the lever as per the clutch.

It is known for fluid to leak past the front master cylinder, building up crud inside the rubber boot. Eventually this crud inhibits the return of the lever preventing operation of the switch. In your case, it sounds like there could be other crud-related issues on the switch.

 

Andy

[AndyS]

Yep, it sure is worth a look.

I'll keep y'all posted.

Ta.

[Boffin]

It is also worth checking the fuses and relays are properly seated - I have had some very strane elecrical problems caused by loose relays in the past.

 

Andy

[AndyS]

Yes, have done the fuses. Removed them all and checked continuity with meter. Removed all relays and checked for corrosion to spades. All good.

Problem not solved.

Thanks though.

 

Andy

[Ken H.]

This sure sounds like a switch or a shorting connection to a switch issue. Intermittent are always a bear, but I’d take a closer look at the front and back brake switches and wiring to them. Especially given the brake light comes on symptom.

[AndyS]

Well, the long and short of it was that after trying all sorts, (checking for intermittent shorts etc and getting the wiring right back to the Servo unit, I finally took it to my dealer. They had it on their rog and the servo was doing all sorts of wrong stuff. The servo would cut in on its own with no brakes touched, sometimes it would turn off with either and both brakes applied (scary). The pressures were also well wrong.

The upshot of all this is that I have bit the bullet and sadly extracted the servo unit from my bike. I have done all the mechanical work which was a piece of cake! and the elevtrical work - also easy.

I managed to get good secondhand parts and all the bits only came to £35. We shall see what the brakes are like soon. I am having problems bleeding the front brake, but you'll see that in another post.

 

So the parts I needed were:

6 new copper crush washers (I could have annealed and re-used the old ones. 071 199 630 72

A non ABS Rear brake micro switch

A non ABS front brake micro switch

A front brake distribution piece - 343 276 509 65

and a small piece of solid brake pipe off an older GS I think.

 

Andy

[whyme]

how are the brakes with no servo?

[AndyS]

how are the brakes with no servo?

 

Well, my honest opinion is:

Front brake feel is exactly the same as with the servo.

 

The rear brake lacked any punch, so I got hold of an R1100RT master cylinder from ebay (this has a smaller bore and therefore more power), and the back brake now feels good.

 

Some folk have said how much lighter the bike feels without the servo.....Well, I think that's rubbish. The Servo does weigh quite a bit, but no where near in the scale of a tankful of fuel.

 

The discipline I am having to re-learn is rear brake usage. I got a little lazy with linked brakes.

 

I am practicing heavy braking to reduce the chances of getting caught out with no ABS.

 

My rear wheel spins beutifully now. When I had the Servo fitted, my back brake ALWAYS dragged the tiniest bit. That's gone now. I think my rear pad life will improve dramatically.

 

If you have any more queries please ask.

 

Andy

[tiny]

im having the same problem with my R1150RT 03 take it back to bmw dealer next week will let you know how i get on.

[AndyS]

im having the same problem with my R1150RT 03 take it back to bmw dealer next week will let you know how i get on.

 

Hi Tiny, welcome to the forum.

Are you having exactly the same symptoms?

If not tabulate them and lets see if we can identify something else.

 

Andy

[tiny]

do you have a datatool alram fitted?

[AndyS]

do you have a datatool alram fitted?

 

 

??????????????

 

Andy