ABS Brakes (again I am assuming)

Steptoe thanks for the information. The red warning triangle stays permanently on and the "brake failure" light (the lamp actually says "brake failure" although I have seen other bikes that say "ABS") flashes 4 times a second. So from what you say it sounds unlikely to be something relatively inexpensive to fix so I could be looking at worse case senario.

If I end up removing the ABS module is there a way to stop the red warning triangle coming on - I'm guessing I can remove the brake failure warning bulb but the red triangle is used for other things?
 
Hunda67 said:
Steptoe thanks for the information. The red warning triangle stays permanently on and the "brake failure" light (the lamp actually says "brake failure" although I have seen other bikes that say "ABS") flashes 4 times a second. So from what you say it sounds unlikely to be something relatively inexpensive to fix so I could be looking at worse case senario.

If I end up removing the ABS module is there a way to stop the red warning triangle coming on - I'm guessing I can remove the brake failure warning bulb but the red triangle is used for other things?
Click to expand...

Before removing anything you need to see if any codes show if you were nearer I would read the codes for you.

This might be worth a read and give you some ideas

http://www.ukgser.com/forums/showth...e-too-high-RED-WARNING-flashing-BRAKE-FAILURE
 
Pukmeister said:
I have no idea why BMW designed the system this way.
Click to expand...

It's to stop excessive battery drain and stops the servos running continuously while still having the brake on. i.e. on a hill etc with the engine at idle while stationary.
 
So it seems the system is partly doing what it is supposed to i.e. pushing rear brake hard and the servo cuts off. But pushing it lightly it just stays on. That would suggest something like low pressure to me but then I'm no expert and it doesn't fit with the other symptoms :nenau I'll try and get the diagnostics read and then see what happens.
 
Steptoe said:
It's to stop excessive battery drain and stops the servos running continuously while still having the brake on. i.e. on a hill etc with the engine at idle while stationary.
Click to expand...

I know that part Neil, I meant I have no idea why the front brake stays on when in use whereas the rear brake cuts out/pulses. You'd think they would both cut out to save battery drain.
 
Hunda67 said:
So it seems the system is partly doing what it is supposed to i.e. pushing rear brake hard and the servo cuts off. But pushing it lightly it just stays on. That would suggest something like low pressure to me but then I'm no expert and it doesn't fit with the other symptoms :nenau I'll try and get the diagnostics read and then see what happens.
Click to expand...

The Servo has pressure sensors, it may actually be working normally if a light touch of the pedal only produces moderate pressure and the servo stays running. I haven't owned a Servo braked GS since about 2008 so I can't remember exactly wether a light touch of the pedal keeps the pump running, perhaps somebody owning an early 1200 can check this ?
 
If I give the rear brake pedal a light touch and release it the servo stays running until I either press the pedal down fully or I switch off the ignition - I've only left it running for about 30 seconds before either switching off the ignition or pressing the pedal fully as I'm sure it is doing no good with it running constantly. I could leave it longer to see if it stops after releasing the pedal but what would be a safe limit for the motor?
 
Is your rear brake light staying on when you release the rear pedal and the Servo pump continues?

If so, it sounds like your rear brake switch is sticking and triggering the Servo unit.

I also recall on the early bikes that the rear light bulb holder is prone to corrosion and this caused issues with the ABS unit. I seem to recall on my 2004 bike I had to remove the rear light cluster via the under tray to gain access to the brake/tail lamp holder, which was quite badly corroded. It might be worth checking yours.

My later 2008 bike has LED lights with better weather sealing.
 
Brake light working properly - release lever and pedal and brake light goes off instantly. In fact all wiring I have checked so far (everything apart from under the tank (which I intend to inspect over the weekend) looks like new in the connectors with no breaks in the wiring - the bike is very clean for a 10 year old bike.

But maybe that brings me on to another point - maybe it is lack of use the last few years? Brake fluid was changed 3 years ago and since then it has done very few miles for various reasons. Maybe it didn't like coming out of this hibernation - although I was using it regularly for a few weeks before the fault showed up without any problems. Bike is also always garaged.
 
Right I've had the tank off today. Wiring all tests out good - the wires to the front fluid level sensor were stretched tight (from factory it looks like) but the definitely test out ok. I've adjusted them slightly so not stretched now. So no chaffed wires anywhere. Fluid levels are good. So it's looking like expense time :(

Today (after 48 hours of not touching it) the self test passed every time I turned ignition on for about a couple of hours or so. So I left the ignition on for a while and didn't touch the bike and eventually after 10 minutes or so warning traingle light turns from amber to red and brake fail light changes from 1 flash a second to 4 flashes a second. I don't know if that is normal if ride away test is not completed (bike in bits) but from then on so far it just goes straight to fault mode (solid red warning triangle and 4 times a second brake failure flashing) :nenau.

However, I have found someone who can read the codes for me next week so I think I'll put it back together and see what happens after codes read.
 
Is the rear stop/tail lamp okay and lamp holder wiring and holder clean and intact?

Some folk had success by simply replacing the rear lamp.
 
Yep couldn't be cleaner in there - bulb is also fine. I'm an electrician so am convinced the wiring has been checked and is all good. It's the hydraulics part I don't like to get involved with.

I've just put it all back together to take it to the guy with the code reader during the next week. I took it for a spin up the road. Started with just residual braking (no servos and no abs) and after half a mile the servos started working but no abs and still fast flashing of brake fail light. Switched it off and on again and then it went back to touch the back brake and the servo sticks on, use the front brake and no servo. So it's never consistent - and I'm confident if I go back to it tomorrow after sitting overnight it will work initially before going wrong again. It's alsmost as if something works after a rest and then stops working if you see what I mean. :nenau
 
I'm all out of ideas now, I agree it sounds like the Servo unit itself at fault if it's doing random stuff.

Brace yourself for one or two probable options: Repair, or rip out. Let's hope it's an easy fix instead.
 
Thanks.

I'm actually coming round to the idea of ripping it out (can't justify or afford a new ABS unit). I've seen the posts about removing it - is there anywhere with some pictures etc. on how to do?
 
Right I have the diagnosis now.

According the guy who has the GS-911 front brake pressure is ridicuously high. This sounds like to me it is actually the "mechanical" rather than the electronics board of the ABS pump. So I have 4 choices:

1. Get rid of ABS and servos with a servosectomy.
2. Buy a second hand one from Motorworks (untested with money back guarantee if it doesn't work and may have to use my electronics as they are not sure if it's off a GS or ST) for £300 and hope it works - but am I just creating a problem for a year or two down the line?
3. Found a company in Germany (https://rhelectronics.de/ if any one is interested) that recons them for €900 + shipping etc. if I send it to them.
4. Buy a new one from BMW.

I've ruled out option 4. I would be interested to hear anyones opinions. Does anyone have one of the early bikes without any problems with the ABS or am I just creating problems down the line if I go for option 2 or 3?
 
If it were my bike, I would flush the brake circuits and servo circuits through with some new fresh brake fluid, ensure all reservoirs are correctly refilled then see if the fault goes. Use the GS911 you have available to reset the fault codes.

You might get lucky and flush out anything that could be causing trouble, or unstick any component within the unit that might be problematic e.g. a small hydraulic valve. I've had a warship unable to sail because of a jammed hydraulic spool valve due to microscopic debris particles, it really doesn't take much to stop hydraulics working and I suspect there must be a pressure regulator within the Servo which should be preventing excess pressure and clearly isn't.

Be sure you are following the correct procedures for the Servo ABS systems and not the later non-servo ABS systems which are different.

All you have to lose is a couple of hours and ten to twenty quids worth of brake fluid.
 
Had it flushed through by the guy with the GS-911. It seemed to work for a couple of miles and then the fault came back :(
 
Remove front pressure relief valves on the modulator and clean - or try swopping over front and rear and see if the problem follows the swop i.e. rear brake now has high pressure. I've a few spare valves kicking around if you need one.
 
Thanks for the offer Steptoe - much appreciated to know someone has some. I'll get them out and check them.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
You must log in or register to reply here.

Similar threads

Brakes again
Replies
7
Views
1,754
se7en
BRAKES AGAIN IM AFRAID!!!
Replies
10
Views
2,076
Jimb


Back
Top Bottom