Intermittent Brake Warning after battery failure - BMW Luxury Touring Community
 
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post #1 of 4 Old Jul 21st, 2019, 9:57 pm Thread Starter
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Intermittent Brake Warning after battery failure

I have a 2002 K1200LT with 36K miles on it. Last week it would not crank due to a failed battery. I replaced the battery with a Yuasa YT19BL-BS. The bike now cranks and starts very enthusiastically, but I will often get a brake warning shortly after turning the ignition on.

The exact sequence is as follows:

1. Turn key on
2. Triangle light comes on and brake failure light flashes at approximately 4 Hz
3. Servo motor initiates test
4. During a good sequence servo sound stops after half a second, triangle light goes out, brake failure light flashes at 1 Hz
5. During a fail sequence, servo sound continues, triangle light stays on, brake failure light flashes at approximately 4 Hz

From my research this indicates that either the front or rear brake system has failed.

I have checked, cleaned, and tightened the battery connections. With the key off, the battery voltage is at approximately 12.6V. Key on 12.45V. During the servo test, the battery voltage drops to about 12.3V.

I seem to get the failure about half the time when I turn the ignition on. It also seems to occur more frequently after the bike has sat even when on the tender. I occasionally seem to get only residual braking when I get the failure indication, but not always.

For reference, I replaced the brake lines with Speiglers last year at which time the entire system was flushed and bleed. I have not had any trouble with the brakes until after the battery was replaced. I know that the Odyssey battery is the one most recommended on this forum, but I have never gotten any motorcycle batteries to last more than 2 years except for the Yausa's.

Any suggestions on how to troubleshoot this? Do I need to measure the voltage at the servo motor? What is the best way to do this?

The failed battery had a strange failure mechanism where it would charge to a normal voltage, but quickly discharge to just a few volts as soon as I turned the ignition on. Could this have damaged the servo motor?
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post #2 of 4 Old Jul 23rd, 2019, 2:56 pm
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Re: Intermittent Brake Warning after battery failure

I doubt that the bad battery cause any harm to the unit since you still get a few good cycles and bad cycles. If it was totaled it would never have a good cycle. A good, fully charged battery should show 12.65 to 12.75 v under no load and it should not drop below about 12.5 during the test. So I would ride it as much as possible to get the new battery fully charged and see what you get then. Also check your static load current. Key off, measure at the battery negative lead by holding the meter lead on the brown wire then remove the brown wire from the battery. It should be no more that about 5 ma.

John
2009 K1300GT Red Rocket
2009 R1200GS (Gone)
2005 K1200LT Ocean Blue Blue Wizard 110 K and counting...
2006 Bushtec Turbo+2 Spell
2004 330 Ci Convertable
K4AN

Have ridden a Motorcycle in all 48
But lack DE, MA, RI and CT with the 2005 LT

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post #3 of 4 Old Jul 24th, 2019, 6:20 pm Thread Starter
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Re: Intermittent Brake Warning after battery failure

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Originally Posted by jzeiler View Post
I doubt that the bad battery cause any harm to the unit since you still get a few good cycles and bad cycles. If it was totaled it would never have a good cycle. A good, fully charged battery should show 12.65 to 12.75 v under no load and it should not drop below about 12.5 during the test. So I would ride it as much as possible to get the new battery fully charged and see what you get then. Also check your static load current. Key off, measure at the battery negative lead by holding the meter lead on the brown wire then remove the brown wire from the battery. It should be no more that about 5 ma.


Thanks. I have had the battery on a battery tender but I have not had the opportunity for a good long ride. I assumed that since it cranked very well, I had a good solid charge.

Hopefully this weekend I will get in a long ride and measure the standby current. I will report back.



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post #4 of 4 Old Jul 28th, 2019, 9:12 pm Thread Starter
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Re: Intermittent Brake Warning after battery failure

I had a lovely 200 mile ride this evening with my wife. The bike threw a fault when I turned the ignition on the first time before we left, but then behaved perfectly the rest of the ride. No faults, good breaking, even when we stopped for dinner and to fill up.

I generally only ride the LT when my wife comes along, so I sometimes forget just how much fun this bike is to ride until I get back on it. It doesn’t hurt that my wife finds it very comfortable also.

Thanks for the advice.


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