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Discussion Starter #1
Dang! Went out for my first ride on the '03 LT and no servo assist. You have to crank on either the front or back brake to get any stoppage at all. I cycled the ignition - no luck. When you turn on the key, you get the 4hz flash and never get to the 1hz flash. I'm pretty sure this means the self-check never completes and that means a significant problem with the servo assist pump. You never hear the initial kick-in of the servo during the self test as you do with my other BMWs. My owner's manual describes this condition (warning light general OFF, warning light ABS/brake failure flashes at 4hz) as only residual braking function available in both circuits /self diagnosis not completed) and that is the case. I read the historical files and current posts and resolution is all over the map, from it fixed itself to new pads to add fluid to reset at the dealer to new battery. I charged my battery (BMW brand) to full charge - no luck. I did a preliminary check of all reservoirs, including under the seat and all seem to be above minimum. I know that a small amount makes a big difference, so I'll pull the plastic and check the rear reservoir closely. But I'm afraid that this means a trip to the dealer. Luckily, I bought an extended warranty (I say luckily, we'll see how it works out) so if the pump unit is out maybe I'm OK. I'll keep you posted on outcomes.
 

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Wrencher Extraordinaire
2005 K1200LT
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14,106 Posts
Unusual that it never completes the initial self test (brakes must not be applied until this is done) fast flash. Might try to unplug and resinstall the connector to the ABS unit and while you have it off look for corrosion on the pins. Stick a small screw driver in the end of the connector and that will start the connector bail sliding out to release it. May get lucky.
 

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Discussion Starter #3
Thanks, John. I'll try it- as soon as I can find the ABS unit. As I said, this is my first LT and I don't yet have a repair manual, just the basic rider's and technical manuals. It's probably buried under loads of plastic? Dwight
 

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Its behind the left panel under the seat, one screw hidden up under the left stde panel, place a wedge to pry the tupperware back or just remove the left side panel, whatever you feel comfortable with...matthew
 

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Discussion Starter #6
Okay - today I finally had some time to work on the bike. Topped up all three reservoirs - no change in symptoms. The brake fluid in the front reservoir was really dirty. I plan to change it as soon as I can, but could that be a cause for my problem? Checked the brake lights and I believe I have either brake lights on all the time or just running lights. There is no change in brightness when I put on the front brakes or rear brakes. Thinking back to my original post, does this mean the brake light switch is stuck? That would mean that the ABS never gets to complete its self check and therefore never lets the servo pump kick in. I think that would explain the problem. Now, my manual only talks about the brake light switch on the handlebar. I have no servo assist on either front or rear brakes. It seems to me that there should be a rear brake light switch as well but it would be too coincidental for both switches (if there are two) to go out at the same time. Any thoughts, anyone?
 

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whitehouse said:
Checked the brake lights and I believe I have either brake lights on all the time or just running lights. There is no change in brightness when I put on the front brakes or rear brakes. Thinking back to my original post, does this mean the brake light switch is stuck? That would mean that the ABS never gets to complete its self check and therefore never lets the servo pump kick in. I think that would explain the problem.
I think you may have discovered something significant. Check both switches.
 

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Wrencher Extraordinaire
2005 K1200LT
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If one switch is stuck the other will not do anything. One or the other is on all the time. You should hear a faint click when they activate. On this machine the switch activates the abs unit pumps and the abs brain turns the brake light on. Keep checking.
 

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Discussion Starter #9
Woo Hoo!! Success! :dance: I got the hand control apart and suspected the micro switch wasn't switching. I sprayed it down with electronics cleaner and lube and did the same with the foot switch. Turned the key and after a stutter start, I got 1hz flasher; checked the brake and got the sweeeet sound of the servo pump. I guess this is kinda' like a guitar or amp pot that if it sits it gets oxidation - contact cleaner will work seeming miracles in those cases. So, now I'm going to take her for a test ride - the first real time to have her out. Here's hoping the fix holds. Thanks to everyone for their help and advice.
 

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That is great news Dwight, now ride and enjoy. :bmw:
 
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