Dangerous ABS

[oddone]

Sometimes after starting my 1150gs the ABS warning light stays on - indicating that ABS is not engaged. According to the manual, this will cause all handbrake effect to be applied to the front brake. Not so! I have had a low-speed incident on a wet road where the rear wheel locked up and nearly sent me flying. To me it looks like the brake servo applies equal amount of brake to front and rear, potentially very dangerous.

Has anyone experienced the same? Is this a fault in my bike only, or is it a design flaw on this particular model (Aug '99)

 

[Steve]

There is no linked braking on a 99 1150GS. The only way you get any braking to the rear wheel is by applying the rear brake lever.

 

[cookie]

There is no linked braking on a 99 1150GS. The only way you get any braking to the rear wheel is by applying the rear brake lever.

there's no servo either.

your battery's shagged.

 

[Kropotkin]

The '99 1150 GS doesn't have servos, and doesn't have linked brakes (as Steve says).

If the ABS warning lights flash out of sync (one after the other) after the bike has been started, then it's likely that your battery isn't as strong as it should be. This starts to become obvious at about this time of year, as it gets colder (especially where you are in Norway). A new gel battery or an AGM battery such as the Hawker Odyssey PC 680 will make a big improvement. Alternatively, start the bike. Ride away (carefully) for 5 minutes, then stop and start the bike, and the ABS warning lights should stay off. But a decent battery is a much better improvement.

The reason your rear wheel locked up is because your ABS wasn't working, meaning that the brakes work, but can lock up if you apply them hard.

From your description of what's in the manual, it sounds like you have the wrong manual, probably from a 2003 or 2004 GS.

 

[Kropotkin]

That's what happens when you take too long to post, someone else gets in with the correct diagnosis ...

 

[oddone]

Thanks for info.
The battery is new, but according to the manual the clue to get the ABS properly engaged is a short pause between flicking on the ignition switch and pressing the start button.
My point is however, that the rear brake does engage with ABS out (malfunction lights flashing), and the brake system is linked (part integral).
The instruction manual is from printed 07.99.

 

[Kropotkin]

If your brakes are linked, then you have the only 1999 R 1150 GS with linked brakes in the world.

And yes, both brakes work fully when ABS is malfunctioning (they would have to, as otherwise, if ABS failed, you would have NO BRAKING AT ALL, which would be frightening, and is what a lot of 1200 owners have complained about). If ABS malfunctions, what happens is the Anti-lock function stops working. Which means, you need to brake more carefully, as the wheels can lock up if you apply too much braking pressure.

Firstly, I would suggest that you take the bike to a BMW dealer, and have them read the error code from the ABS computer. They will be able to tell you what is causing the ABS not to work correctly on startup, and if there is a potential problem with your bike.

Secondly, you are quite right to say you have to wait between switching the ignition on and starting the bike. I usually switch the bike on, wait until I hear the fuel pump finish cycling (that horrible whine you hear when you switch the ignition on), then start the bike.

Thirdly, if you have a wet cell battery (i.e. a battery with acid in), I would switch the lights and heated grips (and anything else) off while you start the bike, and switch them back on once the bike has started. The standard GS battery is slightly underpowered for what is asked of it, and the ABS system is very sensitive to voltage when the bike is started (which is a bit of a design flaw, if you ask me). A couple of Dutch GSers put together a switch which they could use to disconnect the ABS circuit when the start the bike, then switch ABS on when the bike is running, as this saves them a lot of hassle with ABS not working.

 

[gypsy]

I dont know if this will work but my 1100gs has to be upright when you turn on the ignition for the abs to work as opposed to being on the sidestand .

 

[cookie]

i had a brand new DETA battery earlier in the year & that faulted the ABS self check 50% of the time.

if the battery voltage dips below 10v on start up, the ABS will fault. put a voltmeter across the terminals & check.

i have a hawker now & it's fine.

 

[Jimb]

Norway Model

Is the spec for Norway Different ??? Maybe he does have linked servo brakes, the RT's had them at that time.
Any other Norway owners input some info.

 

[Steptoe]

I think oddone's english interpretation is causing the problem - not the "linked servo brakes" .

 

[oddone]

r1150gs production started ca. August '99, with BMW / FAG ABS II as an optional extra
I'm quite capable of "interpreting" what my brakes are doing when I apply the handbrake. You don't have to be Rossi to detect that the rear wheel is locked...
The instruction manual (in Swedish, no misinterpretation there either) states that when the ABS malfunction, the brake system will function a a normal brake system without ABS. What worries me is that it doesn't, as hyraulic pressuse is delivered to the rear brake.
I think I will have to discuss this with the local dealer and get their take. But thanks for the help anyway.

 

[Steptoe]

You changed your battery for a new one, Was the old battery flat, did it cause your ABS to switch off - have you tried re-setting the ABS with the new battery fitted -

If it doesn't re-set, perhaps the modulator is fecked .

Had this on a couple of bikes where the brakes don't work at all - ZILCH . It's not supposed to happen, according to BMW it reverts to "normal" non ABS braking. But both ABS units were filled with water ??? - don't ask me, i only got to fix them.

 

[Kropotkin]

r1150gs production started ca. August '99, with BMW / FAG ABS II as an optional extra.
I'm quite capable of "interpreting" what my brakes are doing when I apply the handbrake. You don't have to be Rossi to detect that the rear wheel is locked...

Yes, but the LINKED brakes weren't introduced until ABS III / EVO, which was (IIRC) 2003, which is why we're all confused. It's not that we don't believe you when you say that the rear is locking up (we're not there to see), it's just that something else must be going on instead. Some options:

- Someone retrofitted the linked brakes, or fitted the linked brakes off another bike. Quite why anyone would do this is a mystery to me (I hate linked brakes), but there's no technical reason it's impossible.

- You are braking with both front and rear brake, in which case it is very likely that the rear will lock up, as you have less feel with the rear than with the front (you are using a foot in a boot, less sensitive than fingers in gloves), and the weight transfer means there is very little pressure on the rear tyre, so they tend to lock up very easily, especially if you're used to braking with ABS. I am, and I find myself always just grabbing a handful of brake, and letting the ABS sort out the mess.

- Your engine idle is set very low, and when you bang on the front brake, you are not pulling in the clutch, and the engine is causing your back wheel to lock.

The instruction manual (in Swedish, no misinterpretation there either) states that when the ABS malfunction, the brake system will function a a normal brake system without ABS. What worries me is that it doesn't, as hyraulic pressuse is delivered to the rear brake.
I think I will have to discuss this with the local dealer and get their take. But thanks for the help anyway.

You'll definitely have to discuss this with your dealer, it's the best course of action. As the manual says, when ABS malfunctions, the only difference in braking should be that the anti-lock stops working.

An idea for how to test whether the front brake is also operating the rear:

- Put the bike on the centre stand, and start the engine
- Put the bike in gear, and let the rear wheel spin (you might want to weigh or tie the front wheel down, so the rear can't touch down and launch your bike off the centre stand)
- Pull in the clutch, and then brake using the front brake ONLY. Best done if you're standing next to the bike, that way you can be sure you are not touching the rear.
- If the rear wheel locks, then your front brake lever is operating the rear. If it doesn't, then it isn't and something else is causing the rear to lock.

Let me repeat, it's not that we don't believe that your rear wheel is locking up, it's just that I (and probably the other posters here) have never heard of a '99 1150 having linked brakes. That's not to say they don't exist, just that they were not standard.

 

[Dick Dastardly]

I dont know if this will work but my 1100gs has to be upright when you turn on the ignition for the abs to work as opposed to being on the sidestand .

Might that be due to the side stand cut-out switch ?? :