Newbie says hi & help

[Laserr Boy]

My first post, I have been lurking in the backround for a couple of years and now find myself in a bit of a pickle. I have a 03 Rockster with 22000 kms that I bought from a stealership 3 years ago with 8000 kms on the clock. I have had the slave cylinder crap out and the gas leaking everywhere. I replaced the slave as well as the QD's myself and after a new battery and oil change went out for a ride on Saturday for the first time this season. It didn't take long to remember why I liked this bike so much, good power, excellent handleing and great brakes. Oh yeah things just couldn't be perfect, after stopping for a while when I restarted her the ABS lights did their thing but instead of going out they just kept flashing and the general warning light can on. I have no brake booster using the lever but I can hear it whine when I use the pedal. It has some brake function but it sure isn't up to snuff. This really sucks and I have to say that in my 36 years of riding all over the planet I haven't had so much trouble with a bike with so few kms on the clock, with the exception of a Royal Enfield in India. I have followed all the threads about input shaft failure, brake failure and final drive failure with growing fear and wondering when my turn would come. Has that happened or is therebe going to simple fix. I always wanted a BMW and this is my first...think it will be last. When I bought the Rockster I was also looking at a Ducati ST4S which I figured would be more trouble than I wanted to take on...

[NoRRmad]

Was the new battery fully charged? Those ABS problems usually crop up with a marginal battery.

[boxermania]

Adding to NoRRmad's post, why don't you go into the R1150R forum, first page and look at the thread titled ABS help? its about 20 threads down the page. I'm sure you'll get some direction out of it.

Good luck.....

[Laserr Boy]

Brand new Odyessy PC680, fully charged. If the battery was low could it cause the booster to work when the pedal is activated but not the lever??

[sweatmark]

...have had the slave cylinder crap out and the gas leaking everywhere. I replaced the slave as well as the QD's myself and after a new battery and oil change went out for a ride...

Good news is that you've already earned your Beemer badge of courage dealing with oilhead problems.

...didn't take long to remember why I liked this bike so much, good power, excellent handling [sic] and great brakes...

And that's the reason we all put up with the nuisances, curing the ills and passing along our learnings to other oilhead owners.

ABS lights did their thing but instead of going out they just kept flashing and the general warning light can on. I have no brake booster using the lever but I can hear it whine when I use the pedal. It has some brake function but it sure isn't up to snuff

1. You're certain that there's no battery or charging system issue?

2. If not electrical in nature, then the iABS has faulted because of one or more error conditions. See this recent thread for some info:
viewtopic.php?f=2&t=17560&start=0

Without further info about your specific symptoms, I'd guess you might have the same problem of low fluid level within the iABS module decribed in the thread above. In your case it sounds like the front brake circuit, rather than rear. Dealer should be able to isolate problem via the diagnostic function built into iABS.

Does your bike have reduced (un-"powered") braking for both front and rear circuits?
Does the ABS & general warning flash occur every time you start the bike and roll the requisite 10-20 feet?
Has the bike's ABS system received required system flush every 2 years?

Worst case scenario is a crapped-out iABS module requiring replacement or removal. We can help with either process if necessary.

[Laserr Boy]

Thanks for all the replies. My battery reads 12.8 V and 14.0V at idle. I went to one of the local dealers today to find out about getting hooked up to their computer and was told it will be a month before I can get a service appointment. I was also told that the much vaunted BMW computer really isn't that good and at least some of the time won't communicate with the bike. They also suggested I should buy a new bike!! I am going to start at the lever and work my way back to the ABS unit and if I can't find any obvious faults I'll perform an ABSectomy and get my self back on the road ASAP. Wish me luck. I have ABS function on the rear only and the ABS light flashes at 4hz as soon as the ignition is turned on and continues to mock me no matter how far I drive. The front brakes do work with more lever travel than normal.

[sweatmark]

OK, it's not the battery. Love your dealer's suggestion of new bike as problem fix - man, that's just great service (not).

Betting it's the front brake circuit fluid reservoir level in iABS module.

If not, then maybe the front wheel sensor, though this would be first I've heard of such failure.

Last possibility would be iABS servo module itself, with front circuit immobilized. Since you've got the tank removal process memorized following QDs and battery, an ABS-ectomy will take you no more than a couple hours' time. Ring me up if needed to discuss the process. Where are you located?

[Laserr Boy]

I'm in Vancouver BC. I'll pull the tank off tomorrow and check the level in the ABS unit, the fluid in level in the master is ok

and looks nice and clean. What has me scratching my head is the lack of brake light when I use the lever but it comes on

when the pedal is used. Also what causes the booster to turn on, the micr switch under the lever or pressure rise in the

master??

[sweatmark]

Lsserr, pondering your info during 4 hour drive this morning. Second guessing my initial recommendation re: ABS unit brake fluid level, as fluid level sensors are wired in series according to BMW electrical schematic. Low level fault should effect both front and rear systems. Front brake switch is likely not trigger for servo pump operation, but fault logic could shut down the booster if switch fails continuity test at startup self diagnostic. The iABS controller logic is unknown.

[sweatmark]

Laserr - anything interesting during your troubleshooting?

[Laserr Boy]

The boss has been keeping me too busy to get to it for the last couple of days. I should have an answer by Sunday and I

have a sneaking suspicion I'm going to need the list of parts and wiring diagram to do the job. On a brighter note I was

reading a post about replacing the stick coils, and someone wondering where to mount the other coils, think I'll have room

under my gas tank!!

[Laserr Boy]

Update..... It appears to have something to do with the front brake light switch. The micro

switch in behind the lever seems to work the brake light as well as turning on the booster.

I removed the tank and cut all the zip ties between the right grip and the ABS unit and as

soon as I fooled around with the lead from the swicth the booster would come on. I removed

the outer sheath to look for a broken wire but it all looked ok and when I test with the meter

the switch works fine. I've put it all back together and the brakes work properly, but the

switch seems a little cranky, i.e the stroke required to get the booster to come on does not

seem consistent. One time just touching the lever actuates to booster, next time it takes a

harder squeeze.

I cannot regard the problem as fixed being that I have no real idea what caused it in the

first place. Going to get a new switch ASAP but I think there will be a real trust issue with

this system, at least for a while. I've always trusted the brakes to perform properly when I

get all over them and if they are no longer trustworthy it might be time to convert them

to something that I have a life time of experience maintaining and

repairing... Further upated after switch replacement.

[Laserr Boy]

Update..Picked up the front brake switch at the dealership today and my brakes worked properly after it was installed..

The catch.. they crapped out after the first 1/4 mile. Looks like I'll be heading down the ABSectomy road.

[NoRRmad]

GOTTA be a frayed wire near the headstock tie-wraps.

[sweatmark]

Maybe a continuity test of the lever switch's wires could confirm a broken wire. Since the ABS brake switches are normally closed (circuit connected), then the iABS control should see the broken/open circuit as an "activated" hand lever switch... not sure why that would cause the servo pump to work or not work.

I can grab my severed ABS harness connector to find the appropriate pins (actually socket in the fancy connector) for front brake switch.

Or you can xABS the iABS for ultimate dependability.

[Laserr Boy]

I'm hoping noRRmad is correct and I can find a broken wire in the bundle. I noticed that there is a small hole near the steering head that has a zip tie going through it and the bundle was really working around when the bars are moved from lock to lock. I got distracted by the switch because as soon as I cut the ties on the wire it all started working again. I checked the continuity and it was all good but I elected to replace the switch in case there was a break in the wire that I wasn't detecting.

Back to the bundles again. I am finding it hard to belive that it is an intermittent problem with the booster but the fact is that if I didn't have intergrated abs i would be riding right now. Removing the system seems like the easiest thing to do to get back on the road

[Daryl.Stamp]

Connector/wiring failure seems like a very plausible cause, as Norrmad advised.
Simply checking w/ a meter won't always be a clear indication of what's going on, as you have to disturb the normal conditions (insulation, closed connector etc.) to be able to get the meter leads on a test point.

In my aviation electronics experience, about 60-70% of electronic system failures were related to connector failure. Sometimes one wire in a connector would have a break at the crimp or solder with the connector pin, when you disconnect to put the leads on the connector it will read OK, plug it back in an it's not OK. Intermittent contact can cause issues that make components fail (like your switch) but switches are usually robust enough not to be affected by this.

Ironically, my maintenenace guy at work & I just fixed some faulty wiring on a Laser marking machine at work that had problems similar to this.

PM me if you'd like to discuss.

Regards,

DLS

[Laserr Boy]

Thanks for the input DLS. I may have had to many preconcieved notions when I started this process. Being that the other end of the switch connector is fastened to the frame I was not thinking in terms of plug failure at the harness end. I have heard so many tales of zip ties being too tight and wire failure around the steering head that I forgot to look at other potential problems.

[Laserr Boy]

Latest update, hopefully last update. As soon as I removed the tank the system started to work again. I have stripped off all of the outer sheathing on the wire runs to the bars and and checked for broken wires. All the wires have been rebundled and rerouted as well as all of the connectors checked and re-secured. I changed the routing of the wire bundles around the steering head, instead of being bundled beside the frame they have been moved to the under tank area, This seems to have relived strain on the front brake switch lead and everything seems to work fine. I have put on app 200kms without any problems.

[sweatmark]

Laserr - good news about the problem fix. Hope it stays that way for you, with no need for iABS surgery.