R1100RS ABSII - Error Code #8 - NEED ASSISTANCE PLEASE

[rmhayes12]

Hello fellow BMW enthusiasts,

I have a 1994 R1100RS with ABSII, and have hit a dead end on my error code diagnosis. Here's what it does:

On start up, both ABS lights blink together. As I ride off, I can hear two clicks, and then the lights go off. ABS works perfectly - front and rear - as tested on some sandy asphalt nearby. Eventually, the ABS lights begin to blink alternatively. There is no rhyme or reason as to the failure - sometimes it happens in the first couple of minutes, sometimes it doesn't fail for over an hour. I cannot tie any variable to this failure.

When I check the ABS fault code, I get #8 which indicates either the front or rear ABS sensor gap is wrong or "other outside influence." I have triple checked the gap - and both front and rear are within specs (.45-.55mm, checked throughout the circumference of the rings). Importantly, simply turning the bike off and restarting it "resets" the ABS, and it begins working flawlessly again - until it eventually fails. Properly resetting the ABS system, clears the error code, but does not change anything else - the ABS eventually fails, again.

So, does anyone know what these "other outside influences" might be?

Thanks in advance for any and all assistance!

Rocky Hayes

 

[6322]

What's the condition of your battery?

 

[gsaddict]

My front is very sensitive to gap. I alternate between 2 sets of wheels and have found that the gap must be a tight .45mm for correct function.
If that does not help then go over all the connections in the front and rear circuits including the main connector on the Modulator itself. Clean and apply some De-Oxit as required.
Corrosion will cause phantom faults.
Check sensor cables for kinking or chafing as well, especially in front.
FYI sensor resistance should measure at 130 ohms +/-

 

[rmhayes12]

Well (knock on wood) I think I may have resolved it. I just rode it for over an hour (about 40 miles around town) and the ABS never failed. Here's what I did, after the generous feedback I received:

1. Rechecked the front and rear ABS Sensor clearance so I could actually notate it: Front - 18 thousandths (.457mm) clears, 19 thousandths (.483mm) does not. Rear 17 thousandths (.432mm) clears, 18 thousandths (.457mm) does not.
2. Thoroughly cleaned the electrical connections for front and rear sensors. While I saw no corrosion, I nonetheless scraped the metal joints on both ends. Applied dialects grease, and re connected. BTW, I checked resistance for the sensors: Front 137.5 ohms, Rear 139.1 ohms.
3. Used some 600 grit sand paper, and cleaned off the mild surface oxidation to the front and rear ABS rings. Blew dust away with compressed air.
4. I lifted the tank enough to unplug the main ABS unit. Here I found corrosion in the lowest left (front) pin. It was white in color. I scraped it away with a small screwdriver, and then used Q-Tips dipped in alcohol to thoroughly clean off all pins. Finally I blew compressed air into both sides of this connector, and applied a thin film of dielectric grease on the gasket.
5. I decided to go ahead and clear the ABS codes, before taking the test drive.

I am cautiously optimistic that it was one or more of the electrical connections that was the cause. If the problem occurs again, I'll come back here and post an update and seek additional ideas about what to do next.

Thanks again everyone!

Rocky

 

[robsryder]

Good on ya for finding and fixing AND replying back on the forum. As an owner of a 94 R1100RS, I find such "real world" experience to be quite valuable.

If there is some way to "sticky" this topic to facilitate future reference, I'd sure be in favor of it.