97 1100RT ABS issues

[omaharj]

Here's the situation The bike had it's 30K service done at 32K. It now has 35.5K The ABS lights indicate a problem. Rode the bike after disconnecting ABS (key off-hit start-key on,start bike) and I was okay. The other day(actually a week ago) I left a gas station after fueling and didn't disable abs. Lights alternateley blinking,I hit the cancel button and head for home. Front Brakes didn't feel right. I twisted the "comfort setting" dial to see if I could make a difference. Not really-they seemed---soft. Not gone,but excessive travel to activate. I get home and order a service manual on CD from fleabay. next morning I start the bike without bypassing the ABS and it wasn't my imagination, front brake lever travel is too long,almost at the end before it works. I decide it would be excessively stupid (for me ) to ride the bike without repairing this issue.

Here's some background info. I got the bike from my anal retentive brother about 1500 miles ago. He mentioned an intermittent ABS light problem and a new battery. I do not know what battery (brand,amps,suitability).

As for me, I'm a fair-to -less-than-middlin' shade tree mechanic. My previous bikes have led me into stator and reg/rectifier diagnosis and replacement. Starter clutch,fork seals,valve adjustments,hope this gives you and idea of my capabilities. I have a multimeter and can use some of it's functions . I have searched for help and found posts on "whizzy" brakes and servo issues but they are no help. I don't think my bike has servos(?)

Anyway, before I take off the tupperware and start rooting around like a pig searching for truffles,any advice? Please don't suggest the dealer,part of what makes it MY bike is I do the maintenance if at all possible. Thanks in advance and I eagerly look forward to the simplest answer being the right one. RJ

[T__]

omaharj, I presume you have checked the front master cylinder to make sure you aren’t low on brake fluid? If not start there..

 

Next pull the failure codes from your ABS controller to see if that points to a smoking gun..

 

If nothing found,, then do a front circuit brake bleed complete with bleed fitting on the ABS controller (maybe for some reason you have air trapped in the ABS controller)..

 

Your problem might be something simple or more complex like a stuck piston in the ABS controller..

 

Added: I guess I should add this so you can pull the codes..

 

 

 

-(Reading ABS 2 controller stored fault codes)-

“Make sure battery voltage is at or above 12 volts”

 

1)- First,, place analog voltmeter between pin #2 of ABS diagnostic connector & ground.. (don’t use a digital voltmeter as most won’t respond quick enough to show stored codes correctly).. Another way is to use a LED & resistor in place of the voltmeter..

2)- Then,, turn ignition S/W on..

3)- Voltmeter should indicate (close to) a steady 11volts,, (IF) no fault codes are stored..

4)- If it has stored fault code(s) in the ABS controller it should show as voltage swings or drops.. To find ABS code or codes just count the voltmeter needle swings towards zero volts..

 

 

-(Here are the ABS 2 fault codes)-

 

1)- front pressure modulator..

2)- rear pressure modulator..

3)- front sensor..

4)- rear sensor..

5)- battery voltage low..

6)- ABS relay..

7)- ABS control unit..

8)- sensor gap front or rear..

 

 

-(Canceling of ABS 2 stored codes)-

 

1)- first,, ground pin 2 (center cavity of diagnostic connector) to clean chassis ground using a jumper wire..

2)- then,, turn (on) ignition S/W..

3)- then,, push (& hold) ABS button on dash (for at least) 8 seconds..

4)- then,, release the ABS button..

5)- then, switch ignition S/W off and remove ground wire from connector pin 2..

6)- then re-check for any stored fault codes..

 

Twisty

 

[smiller]

I'm not certain the ABS lights and the braking problem are necessarily related. It sounds like you either have a bad (leaking or bulging) brake line or a leaking master cylinder. Is your brake fluid level dropping? If so you have a leaky line, if not perhaps a problem with the master cylinder.

 

Now the ABS lights... under what cirsumstances do you see them? Be aware that there is a common problem with ABS faults upon start on the 1100 models due to low battery voltage, could this be what you're seeing? You could also try seeing if you have any ABS fault codes stored, on the 1100 all you need is an LED or fast multimeter to read them.

[omaharj]

I'm a little slow,what was that first thing? Check the master cylinder? IT's EMPTY!! I did not have any leaks in the last two months-I'm sure of this. Garage floor is pristine. I'm thinking last fluid change it wasn't topped off after finishing the bleeding and a bit of brake wear (I've already practiced panic stops from 40MPH-0 a number of times shortly after taking owmership.)

Anyways, I'm going to see if I have some unopened brake fluid lying around (it may be DOT 3 which I'll have to check to see if it's OK to use) After that, check the codes and go from there. I was sure this was going to be a $700 problem with me sweating bullets every step of the way. I can handle embarassment better than spending money,hehe. I'll post more when I know more. Thanks RJ

[vizhip]

I'm going to see if I have some unopened brake fluid lying around (it may be DOT 3 which I'll have to check to see if it's OK to use)

 

According to my Clymer's manual, DOT 4 is the recommended fluid, but only from a sealed container, because it draws moisture, which causes it not to work very well...

 

Regards -

-Bob

[smiller]

I'm a little slow,what was that first thing? Check the master cylinder? IT's EMPTY!! I did not have any leaks in the last two months-I'm sure of this.

I was too, until I finally found the pinhole leak in my front brake line. The leak can be very subtle and appear more as wetness on the line than an obvious leak, and if so could easily evaporate before it would show on your garage floor. Refill the system and then examine carefully for any leaks (especially in the rubber lines) while applying pressure to the brake lever. More than likely you'll find something...

[omaharj]

I filled the master cylinder with dot 4,I had to go to the auto parts store. Magically, the abs system lights are no longer blinking in an alternating pattern. I ASSumed the previous maintenance must have been faulty. Thanks Smiller for reminding me ro be thorough. Thanks for the help guys and I'll followw up when I get a chance to relly check the line in the daylight and also check codes. By the way,would a two wire continuity tester work to check codes? I think I have one of those somewhere.... RJ

[T__]

omaharj, I will just add a little to what Seth said above..

 

Also check the rear of the master cylinder (where the lever contacts the piston) for signs of seepage & look CLOSELY at the front caliper piston area for sighs of leakage or crud buildup.. (I have seen seepage in both these areas on other BMW’s)

 

If nothing found externally maybe remove the fuel tank & look around on the ABS controller..

 

If nothing found with a general look-see you might try tie strapping the brake lever to the twist grip in the brake applied position overnight.. If you are leaking anywhere that should show the area the next morning..

 

Remember brake fluid does evaporate over time so a very small seepage could disappear before being seen (especially in very hot areas like brake calipers)

 

 

Twisty

 

[NonComp]

This may be stating the obvious, but if the master cylinder fluid level was run down to the point where the reservoir was empty, simply filling the reservoir is not enough.

 

In addition to looking for a leak, you must bleed all of the brake lines to remove the air in the system. That includes the two bleeders on the ABS unit under the tank.

[T__]

Glen, not necessarily.. As long as the air didn’t get pushed down far enough to get around the first bend & up the to next high spot in the system they will usually self bleed right back up the hose into the master cylinder..

 

As a rule once the master cylinder runs low on fluid it takes a little air into the piston area so then doesn’t have enough hydraulic pressure to force the air down the brake hose very far due to air compressibility..

 

There is a slight chance that a little air will stick in the brake hose to master cylinder banjo bolt area but if that happens it can be bled right at the bolt..

 

Twisty

 

[DonSydney]

Can someone point me in the direction of the thread(s) that shows the fix for the low voltage ABS problem on the 1100RT ? Have done a search with no luck..

 

Cheers

 

Don

[Boffin]

Can someone point me in the direction of the thread(s) that shows the fix for the low voltage ABS problem on the 1100RT ? Have done a search with no luck..

 

Cheers

 

Don

 

Link to IBMWR tech page

 

Andy

[DonSydney]

Thanks Andy.

 

Don

[Mark K]

Can someone point me in the direction of the thread(s) that shows the fix for the low voltage ABS problem on the 1100RT ? Have done a search with no luck..

 

Cheers

 

Don

 

Link to IBMWR tech page

 

Andy

 

 

I hadn't seen that before. That's interesting. Have many done this mod? I thought the ABS fault was a useful battery life indicator and would rather have it than not.

[Boffin]

Can someone point me in the direction of the thread(s) that shows the fix for the low voltage ABS problem on the 1100RT ? Have done a search with no luck..

 

Cheers

 

Don

 

Link to IBMWR tech page

 

Andy

 

 

I hadn't seen that before. That's interesting. Have many done this mod? I thought the ABS fault was a useful battery life indicator and would rather have it than not.

 

It is a useful indicator only if you like changing batteries prematurly with the associated fiscal and environmental costs.

 

Andy

[smiller]

I thought the ABS fault was a useful battery life indicator and would rather have it than not.

As Andy intimated, not very useful since it 'indicates' battery replacement about two years before it's really necessary.

[Mark K]

I thought the ABS fault was a useful battery life indicator and would rather have it than not.

As Andy intimated, not very useful since it 'indicates' battery replacement about two years before it's really necessary.

 

Right. Not that I rush out and buy a new battery when I get the fault. I just like knowing it's there. Mine started doing it last winter in the cold and will also do it when the bike hasn't been ridden for a number of weeks. I have no immediate plans to replace the battery.

 

That said, the battery just died on my pickup last month with absolutely no warning, leaving me stranded until I could flag down a jump. It went from apparently fine to completely gone in between driving to lunch and leaving the convenience store (nice lunch, huh?).

 

If I had some warning, perhaps I would have looked it up and found that it was indeed over 6 years old and perhaps I would have replaced it preemptively. It's probably just my recent bad experience that makes me say I'd rather have the fault than not.

[NonComp]

I did this mod and it works a treat -- no more erronious ABS errors on cold startup. I am still using the same battery 2 years later and have never had a dead battery issue.