[sully2028]

Need some advice re alternating flashing ABS lights on my 2001 LT (114K miles, recently replaced front brake pads). I first checked the brake fluid in the front and rear reservoirs, and topped off both of them. Didn't solve the problem. Then replaced the battery (went from a Yuasa 51913 acid that was 4-1/2 years old, continually charged with Battery Tender Plus trickle charger) with a Universal Battery (sealed UB 12220). Still didn't solve the problem.

I am wondering if the universal battery just isn't up to the task, and should I go with an Odessey or other brand name battery. Or could there be something malfunctioning in the brake system.

Any advice would be appreciated.

 

[jzeiler]

Dan,

IIRC both of your bikes have the ABS II system. None of the reservoirs are monitored so you have some sort of ABS fault. You can read the fault code yourself (post on here some where I'll see if I can find the link) or some one with a GS-911 unit can do it as well. Any number of things can cause it from a stuck piston, wheel sensor to low battery. Only way to tell is to get the fault code.

Here you go ABS II

 

[Lee510]

Here is one of the threads about flashing ABS lights. See post #3 from the esteemed John Zeiler regarding the wiring harness and the connections to determine the problem with the system. --> http://www.bmwlt.com/forums/showthread.php?t=36384

 

[sully2028]

Thanks to John and Lee for their input. Very helpful.

I have corrected the problem. Here is what I did.

First, I covered the flashing ABS lights with tape. I was prepared to just ride the LT like that, realizing that I would have brakes but no ABS brakes. I didn't want to spend $2K on a new ABS unit, which could only be diagnosed/installed by a BMW dealer. And my brother has a 1991 K100RS that has had flashing ABS lights since he got it; he as put over 15K on it with tape over the flashing lights (ie, brakes but no ABS brakes).

So then, yes I followed the procedure referred to by John and Lee and tapped into the diagnostic cylinder with a voltmeter. I got no pulses, meaning that the procedure didn't work (or there was nothing wrong with the ABS unit itself - ? - but of course that did not occur to me). Back to my first approach of keeping the tape over the lights.

After some thinking and reading in Clymer, I checked the air gap on the front and rear wheel ABS sensors. The correct clearance should be between 0.45 and 0.55mm. The front gap was fine, but lo-and-behold, the rear was wide, about 0.65mm. So I removed the sensor, took out two of the spacer shims, and cleaned up and reattached the sensor. That did the trick and the ABS lights are no longer flashing alternatively.

I guess wear occurs on the ABS sensors after eleven years and 115K (my mileage on the 2001 LT). I never experienced that before but was glad that was the solution. Again, much thanks to John and Lee for their recommendations.

 

[deputy5211]

Is always nice to read when a potentially dreadful problem seems to be cured with a relatively simple fix courtesy of the folks on this forum. Never get tired of that!

 

[jzeiler]

Glad you found that Dan. More likely is the bracket got bent some how changing the gap.