Alternating flashing brake warning lights...

[bentbeemer]

I am new to the forum, seems to be a lot of good info here! My wife and I started out on a leisurely ride today only to get 2 miles from our house and I noticed the brake warning lights were alternately flashing. I returned to my garage and checked things out. Brake fluid is dripping out of the vent tube that hangs down by the right foot peg. This must have been going on for a while because the rear wheel and tire had a splattering of brake fluid on them. I have searched the forum and read the various causes for these lights to act this way: weak battery, taillight out etc. the one that makes sense is the low brake fluid. I guess if it is running out of the vent tube it would be low…. What can cause this?? Any ideas? The bike has not been over on its side. Thanks, John

[The Meromorph]

Vent tube? On a brake system?


Possibly a fractured brake line?

[AndyRR]

Unless you have a severed brake line, that isn't DOT fluid coming out of the vent hose. You'll have to see where that line is coming from. I don't think any of them should have oil. The flashing lights indicate an ABS fault condition. They flash at different rates depending on the fault. There is a sticker on the alternator belt cover or thereabouts giving a description of the fault, but without going out and checking I think it's something like 1 HZ - be careful and get it checked ASAP, 4 HZ - you may not have brakes.

Do you have ABS?

[bentbeemer]

Guess I should have mentioned its a 2002, R1150R, about 35K miles with ABS. The fault code in the owners manual says it could be low fluid. The tech at Bob's BMW says that I probably have an ABS problem but that the brakes will still work....they do. IT is brake fluid coming out of one of the three vent tubes on my machine. Unless I messed something up when I did the circuit brake service last Spring, I am clueless as to why it is venting fluid.... if I overfilled the ABS reservoir and now it is venting the excess, it should stop when it reaches the correct level... it's got me stumped. I am going over to Bob's today and see if I can talk to someone more on the subject....

[bentbeemer]

Just returned from Bob's. Tech said that I probably over filled the resevoir and that other than the bike falling over this was the only thing that could cause this.... I mentioned the flashing lights and he said that too much pressure could cause the warning, I guess too much fluid means too much pressure.
I have been riding the bike since Spring with no problems... seems odd that it would start doing this now. Perhaps the change in temperature? I will have to remove the tank and see what I have done...

[sweatmark]

I noticed the brake warning lights were alternately flashing. I returned to my garage and checked things out. Brake fluid is dripping out of the vent tube that hangs down by the right foot peg.

Certain that the ABS warning lamps were not flashing at beginning of ride, following the self-check at low speed?

If fluid is dripping out of one of the vent tubes, then it's either fuel, water condensation, or battery fluid. I don't recall any vent tube for the iABS system when I removed mine. Could brake fluid be following the battery vent tube down to the ground?

Is the iABS brake servo power working? The difference between power-assist and back-up (weak) braking function should be obvious.

Original battery?

[lionlady]

Observing Anton Largiader as he did my brake service last month. The ABS/servo system is weird. The fluid in the handlebar reservoir is completely separate from the fluid that is in the ABS unit under the tank. They need to be filled/serviced separately.

(I learned from my observation that I'm not comfortable doing the brake fluid service myself.)

P

[AndyRR]

I have the same bike and have recently taken it apart and put it back together. Twice. I don't recall any vent hoses for the ABS. It is a sealed system.

Thinking back to my last ABS flush, the only place it could be overfilled is at the handlebar. This is a control circuit that goes to the ABS unit. Like she said -

The ABS/servo system is weird. The fluid in the handlebar reservoir is completely separate from the fluid that is in the ABS unit under the tank. They need to be filled/serviced separately.

If the handlebar fluid level is OK you might want to bleed the system once more. Double check everything. What is your ABS filling setup? Next, take it to Bob's and have them hook it up to their computer. Hopefully, the ABS will tell them something meaningful. I have always been happy with the service at Bob's part dept., but have zero experience with their service.

Your ABS makes the normal squealing sound when applied at a stop?

I test drove a R1200C for a friend that was considering purchase. The ABS light was flashing and I confirmed, at speed, that the brakes work but the ABS was NON functional. Be careful. I'm not sure Bob has given you good advice.

[iowabeakster]

The alternating flashing lights are the warning for low fluid level in the ABS unit.

There is a vent tube... you already know that if you've done the service. In fact there are two vent tubes. On on top of each reservoir on the ABS unit. They join together at a Y junction and run down to a catch basin (a goose neck) then down to the location of the other vent tubes by the footpeg. It may take some amount of time for the fluid to crawl down the tube...fill up the catch basin, and then drip all the way down. Over filling the system is quite easily done...but that only explains half the issue. That explains the dripping. That does not explain the low level in the ABS unit.

Like the folks at the dealership said, if the bike was tipped over, that would be a likely cause.

SInce the bike was not tipped over...I would suggest that the fluid was not set at the proper level on your last system flush.

If you filled the reservoir(s) before the calipers were put back on the bike, and the pads are fairly worn, this is likely. This is because in order to put the calipers on the rotors, the pistons must be fully retracted into the caliper. This may push some fluid out the vent tube (more properly called an "overflow tube"). Then, the first time you operated the brakes, the pistons extended and pushed the pads agains the rotor. This made the fluid level in the reservoir drop. As your pads have worn since then, the level has kept dropping, until it is now too low.

Do the flush again. This time, make sure to put the calipers back on the bike before you make your final check of the fluid level. Once the calipers are on, squeeze the brakes to extend the pistons and push pads tightly against the rotors. Then make your final fluid check, and fill to the proper level.

Since the system is working, the ABS is fine. This should only cost you a big bottle of brake fluid.

[bentbeemer]

I have probably ridden the bike 15 times since I did the brake service. Everything seems normal, all the correct squeals and such. I am positive that I have messed up the service.... now that I have had time to ponder all of the input. I will pull the tank and see what's up.
I read something just a few days ago, "These back yard mechanics are going to make me rich". I guess that sums up this experience....at 65 and retired on a pension I have to save where I can. My 1967 R50 never gives me any trouble and is so simple anyone can fix it. These new bikes are amazing and so fast, but the complicity is staggering.
John

[bentbeemer]

GEEZE, I don't know how I did this but the front wheel circuit reservoir is overfilled and the rear wheel reservoir is definitely low. I will search for any kind of leaks for the rear. Disappointing that I caused this.
Another problem has (of course!) presented itself, when I disconnected the fuel line quick disconnect a piece of the end tube has broken off. It is a black cylindrical piece with an "O" ring on it. I was able to pull the piece out from the other side of the connector... now I will have to wait for Monday to get a part from Bob's. Thanks for all the ideas and help.

[iowabeakster]

Sorry to hear of the troubles, don't feel too bad. The ABS service is a pain!

I doubt that you'll find any leaks (of course anything is possible). Like I said in my first response, after you've done the bleed job...get the calipers back on the bike...squeeze the brakes to extend the pistons...then make your final fluid level inspection and filling.

Don't feel too bad about the plastic fuel line disconnects either. Many (including the techs at the dealers) have broken those pieces of junk. Even better, start a new thread about "I broke my plastic fuel disconnect". You'll see how many people have had that issue. Replace them with something much better. Like these:
http://www.beemerboneyard.com/cpcqkdiscon.html

If you put the words...quick disconnect...into the search box at the top of the page, you will get lots of information about replacing those things. In fact, I got 124 matches.

Read through all those threads...you will know exactly what you need to know... which is that you should replace the fuel line also...what kind of fuel line...what kind of clamps...what a pain the stock clamps are to remove...

[bentbeemer]

I think you are correct about the calipers, thats probably where I screwed up...
I searched for a leak and did not find one.
I see what you mean about the quick disconnect problem...I guess the plastic becomes brittle after time....you would think this would have been an obvious issue for the engineers at BMW. Why not use the brass ones to begin with, cost I guess.
I will get on the phone with Beemer Bone Yard in the morning. I had no problem getting the old connector off... I cut the small loop right across the middle with a Dremel tool and a diamond wheel, never touched the hose, then just spread it apart.
After it was off I slid a really small screw driver between the hose and the connector and worked in some Armorall, it pulled off quite easily then. Thanks,
John