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Discussion Starter #1
2003 LT.....turn the key on and brake lights are on: the LED one on the top case and of the two outside brake lights are super bright and the middle light (license plate?) is not as bright. Servos work as they should. Changed the relay thinking that would be it, still on. This is my first BMW and I havent had a relaxing ride yet. The Brake warning light was on initially and I changed the brakes and topped off the fluid, and changed all the rear brake bulbs. I had my 6 yr old tell me if the brake lights were working and he said they were. But I read a few posts that say the bulbs can set that warning light off even though they are still lit, for $10 i figured I'd try it.
Please give me a hand. thanks :confused:
 

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Could be one of the brake light switches. Try listening for the slight click at the switch when you pull the handle or push the pedal.

My relay went bad and the lights stayed on all the time (key on or off).

Bob
 

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Discussion Starter #3
what activates the lights, the little micro switch on the foot pedal? I disconnected it and the brake light was still on. The front seems to sound ok. The rear servo gets stuck on every now and then too. What activates rear servo?
 

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2005 K1200LT
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The switches (front and rear) send a signal to the brake servo unit. It in turn sends the signal to the brake light relay. If either switch is sticking then the lights will be on. If both are off and the light is still on then I would suspect a stuck realy (in the electric box UNDER the fuel tank). Also a malfunction in the ABS servo can cause the lights to be on but that is rare. But as Bob said the relay is fed from an "unswitched" source so if the relay was stuck the lights would be on with the key off. I would check the front switch next. If that is good then there may be residual pressure in the control lines to the ABS unit as pressure alone will fire off the servos. I don't know if that would also light the lights or not.

The center bulb in the tail light assembly is just a running light unless it has been modified.
 
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As stated in previous message, the servos will kick in with either of:
1) front or rear brake switch making contact (or being stuck in "clicked" position)
2) enough pressure on the pedal (or lever). This fuild pressure is felt inside the ABS-UNIT with pressure sensors and will activate the brake light circuit (even if the brake-switch was defective).

The most common cause(s) of having a "stuck" brake-light are:
1) Pedal does not return fully to normal resting position (dirt, debris or pedal shaft needs grease)

2) Adjustement of the rod leading to the rear brake master-cylinder is incorrect (on the K1200LT, the whole mecanisn is hidden behind the right footpeg holder).

Item 2 above can cause the brake switch to go on too easily OR continuous pressure into the master-cylinder as if you had your feet pushing the pedal down.
 
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Discussion Starter #6
when I turn the key off it shuts the servo down (if it is stuck on at the time) and the brakes lights go off (they are on ALL the time)at the turn of the switch also. I changed the yellow relay under the tank too, still no fix. The issue is sporatic at best. I will adjust the pedal and see if that is it. Thanks for the ideas, keep them coming! I need all the help I can get.
 

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You need to make your own decision about maintaining or fixing this . The "integral ABS" (with servos), including various switches, is a complex system and it is critical to your own safety. WHEN or IF it goes in fault mode, all you have left is "residual braking", which is not much.

BUT ONE THING IS ABSOLUTLY SURE, if you leave the ABS-unit servos (electric pumps) work overtime, the unit will fail very quickly and the cost brand new is $US 2400 plus installation.

I suggest you do not ride it until the issue is found and do not let the servos work for several continuous minutes.
 

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Sounds a little like a problem I had after I did a major service on my RT with the servo brakes. Everything went well until I tried to go for my test ride. Found eventually that it wasn't the rear brake switch, but rather a wire fouled in the footplate that shorted to ground. Word of caution to you on the rear brake (and I think front brake too) switches. In a "normal" system, the switch closes and completes the circuit. On our servo systems, the switch OPENS and breaks the system. So, if your rear brake switch is broken, sticky, dirty, or any plethora of things, it can, and will, give you the symptoms that you describe. Also, a couple of years after my issue now, this summer my rear brake switch had some debris in it and wouldn't let it return fully off. This gave me the flashing light after startup and loss of brakes until I cycled the rear brake lever several times.

Your bike I'm sure is going to be a great bike. The LTs are fantastic bikes! And, despite what you might read here, the servo brakes are good brakes, but they can be quirky. My advice to you is to check your rear brake switch, make sure it is not bad, make sure it is properly adjusted and when you get your brake issues ironed out, I think you'll fall madly in love with your LT.
 

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Discussion Starter #10 (Edited)
I will check the switch again tonight.. I hope your right. Well the rear little micro switch tests out OK, but now (key on) when I hit the front brake the servo operates, but when I hit the rear....nothing.. note: the rear brake light still on as soon as you turn on the key. Any other ideas guys?
 

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Discussion Starter #11
OK, I did a little more checking... That micro switch on the rear brake has 4 volts on both wires and when you hit the brake one goes up a few volts and the other goes down a few volts. But on a side note I disconnected the switch.............connected the two together to bypass the switch.. although the servo would turn on and off THE BRAKE LIGHTS WOULD NEVER GO OFF!!!!!! AAHHHHHHHH :(
 

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I had this issue with my '99. Remedy was a new relay. The part is less than $20, though the tupperware & tank need to be removed. The relay box access is still very snug.

I don't recall what it is, but there is a short term remedy that will get the light to go off (pulling the brake lever rapidly several times?). However, the light will inevitably "stick" on again at some point, causing a dangerous safety issue for you in traffic.

Someone on the forum advised this was a common problem & likely the issue. I'm experienced & comfortable removing the tank, so I just had the part sent via UPS & did the relay swap. I figured the $20 and a couple hours of my time was a low risk course of action. Solved the problem for me.

If you are uncomfortable trying this, take the bike in to your BMW guys.
 

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Discussion Starter #13
I replaced the relay, the plasic removal wasn't too bad. Still same result. BRAKE LIGHT STILL ON and servo sticking on every now and then too. "Key off" seems to reset servo, but not brake light
 

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Discussion Starter #14
I figured out something: When bike comes down to an idle it kicks the general warning light on. If I turn the bike off and start it back up and ride on the highway instantly the light never comes on, but when I pull the clutch in and the bike goes to idle, light comes on. Battery has full charge and all tail lights are new.
 

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myrph226 said:
what activates the lights, the little micro switch on the foot pedal? I disconnected it and the brake light was still on. The front seems to sound ok. The rear servo gets stuck on every now and then too. What activates rear servo?
Don't know about iABS but disconnecting / removing brake light switch *activates* the brake light in ABS2.
 

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2005 K1200LT
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C-A-D said:
Don't know about iABS but disconnecting / removing brake light switch *activates* the brake light in ABS2.
It should not since the ABS is not connected to the brake light relay and the relay is fed switched 12V from each of the brake light switches. Removing the switch will not send 12v to the relay. There must be another issue going on here.
 

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One thing that gets overlooked a lot is the grounds. When ever I see an electrical gremlin and the basic checks are good, I clean and confirm (ALL OF THE GROUND) circuits. Sometimes I add even more grounds.
Don't just look and assume. With the circuit powered up, use a voltmeter to measure the drop in the connection. Should be super close to zero volts.

Bob
 

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I am also having the same problems. the iabs is faulty the brake lights are on all the time. replaced both brake switches and the relay . still the lights are on. Now the lcd display has failed and the fuse is blown. I am beginning to not like this bike only had it 4 weeks 2000 k1200lt with iabs.:frown:
 

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If you have a 2000 bike it has ABS II not iABS and it should say "Brembo" on the front calipers. There is no connection to the ABS II and the brake lights so either you have a miss adjusted switch or a shorted wire keeping the brake lights on.
 

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Over here in the uk IABS was fitted to k1200lt from late 2000. it has the bmw calipers. the iabs was not used in the usa untill later.
 
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