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Good morning fellow K bike riders. This is my first K bike, well first BMW for that matter. I purchased the bike a few months back, used with 30k miles on the clock. It's been fairly reliable, my only real performance or safety hindering fault came up recently. The beloved ABS servo/module. I ride all year round, and get caught in the rain, sleet, sub freezing temperatures, and etc fairly often. Well I caught some rain, arrived home and parked the bike. Went out to go for a ride about a week later, the battery was completely dead. I hooked up a float charger, went to work for 2 or 3 hours, came home, and the ABS servo was buzzing non stop with the key in the off position. Turned the ignition on, squeezed the brakes a few times, turned the motor over, and turned the ignition off. Buzzing quit, so I went on with my day. Hours later I hear it again, so I go out and unhook the battery. Fast forward to the end of the next day, I've disassembled the bike, inspected component plugs, wires, micro switches, etc. I couldn't find any moisture, wire frays or obvious brake switch failure. The problem with the abs has changed though. Servos no longer running with the key off. I charged the battery with the negative cable unhooked over night. I hooked the battery up, energized the ignition, and I didn't get an ABS servo buzz at all. I switched the ignition off and on numerous times with no change. I then started the bike, rode a few hundred feet, shut the bike off, and reenergized the ignition. I then received a servo buzz upon ignition. When I energize the ignition, the ABS servo does a quick check buzz, brake failure light flashes rapidly, I start the bike, get moving around 5-10mph, brake failure light still flashing rapidly - red triangle, and I no longer have servo assisted brakes. Stopping power is greatly reduced. After hitting front and rear brakes numerous times, switching the ignition off and on, I now get constant servo buzzing when the ignition is energized. This trouble shooting was done last weekend, the bike has sat with the battery disconnected since then. I'm assuming moisture is the culprit, do to the fact that the issue is changing. Possibly in a micro switch. Since I've purchased the bike, the rear brake has not worked properly with the abs system. I always had to stand on the pedal, and after learning about the abs system it's clear that the servo does not assist it. If I turn the ignition on and the servo is quiet, when I press either brake the servo does not whine. Servo used to whine when I hit the front brake. If I disconnect the micro switches, theres not much of a change in pattern that I could see. My rear brake light functions properly with both brakes. Anyways, I've never owned a bike with obd scan ability. I hate it and would much rather have flash codes. Regardless, I still need to solve the issue. I have a 16 pin obd2 used for the average car, I have access to a laptop, and I have a smart phone. What are my options for reading/clearing faults? I prefer not to travel to a BMW powersports dealer, there's nothing close by, and I would much rather solve the problem myself. All help is appreciated, thank you.
 

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2009 K1300S, 2017 S1000R
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I went to "tools" in the menu ribbon selected advanced search and typed in "servo ABS failure". Here is the result:
https://www.k-bikes.com/forums/search.php?searchid=467987
You have the Servo ABS system installed in BMW bikes from 02 to 06. It fails. Many people bypass it there is a company in Germany who will repair it for about $1000 round trip with your unit. They also sell a bypass blanking plate with new electronics in it to run your brake lights and speedo.
You might check first with a complete fluid flush and correct levels and see how it goes. There are four separate systems, front wheel control reservoir on handlebars, front wheel supply with reservoir in ABS unit, rear wheel control with reservoir in back by pedal and rear wheel with reservoir in the abs unit. There are videos and descriptions in many locations on the web how to do this work. You can buy a GS-911 to help with bike work concerning the various computers and components on the bike. Some have come up with a cheaper app and OBOII reader system.
Think of a subject and put it in the search engine and you will get lots of previous threads. BMW will gladly sell you a new Servo unit for about 2300$ but I think your bike is not in that value zone.
German company: https://rhelectronics.de/
A company in Idaho has been saying someday they can repair them but not heard of success yet. Module Masters in their name. Good reading tonight.
 

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The servo ABS is prone to failure.
Worst case is that the circuit board got water and then its toast.

The servo does draw quite a bit of power. When turning the key it primes the 2 hydraulic circuits to 20 bar (280psi).

A near dead battery, although still capable of starting the bike can cause the ABS to go funny too. The alternator is capable of keeping the bike alive, but trying to charge a bad battery and supplying a high power demand ABS can be a problematic.

Next issue that these ABS units can have a failed/failing pressure sensor (there is one for each circuit).
A failed sensor can also be caused by a corroded circuit board.

I could probably write a whole book for you on how shitty this Servo assisted ABS unit is.

The easiest and 2nd cheapest way to read error codes on your bike is to get the „MOTOSCAN“ app, the unicarsys obd2 reader and a adapter plug.
If you do buy the setup, buy the ultimate version.....

GS-911.....too expensive, and is not as comprehensive as the motoscan app.

The cheapest option would be to learn german and download the BMW EDIABAS software (INPA, NCSExpert, Tool32.....)
 

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I had an issue with the ABS on my 2005 RT (same ABS unit) with the rapid flashing ABS light. If you turn on the ignition and start the bike without letting it go through the self test, the ABS light will flash and you will not have brakes.
 

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Discussion Starter #5
The servo ABS is prone to failure.
Worst case is that the circuit board got water and then its toast.

The servo does draw quite a bit of power. When turning the key it primes the 2 hydraulic circuits to 20 bar (280psi).

A near dead battery, although still capable of starting the bike can cause the ABS to go funny too. The alternator is capable of keeping the bike alive, but trying to charge a bad battery and supplying a high power demand ABS can be a problematic.

Next issue that these ABS units can have a failed/failing pressure sensor (there is one for each circuit).
A failed sensor can also be caused by a corroded circuit board.

I could probably write a whole book for you on how shitty this Servo assisted ABS unit is.

The easiest and 2nd cheapest way to read error codes on your bike is to get the „MOTOSCAN“ app, the unicarsys obd2 reader and a adapter plug.
If you do buy the setup, buy the ultimate version.....

GS-911.....too expensive, and is not as comprehensive as the motoscan app.

The cheapest option would be to learn german and download the BMW EDIABAS software (INPA, NCSExpert, Tool32.....)
Thank you all for your responses. I'm learning as I go. I downloaded the moto scan app, purchased a bluetooth obd2 scanner and a 16-10 pin adapter. After purchasing the app and all the tools, left me around $100 lighter. I charged a newer battery and tested after clearing all faults. The faults I'm getting with the abs system are

ABS: D347 CAN Bus Fault, Undervoltage 624E

Central Chassis Electronics: No CAN Message from ABS A31B.

With a good charged battery, my ABS servo is contantly running with the ignition off, and doing nothing with the ignition on. I did notice when energizing the ignition, the ABS system doesn't do a quick buzz. When I shut the key off, the ABS system does a quick buzz, then will run constantly or do nothing. I'm curious if I can scrounge up a wiring diagram of sorts? I honestly think it's the ignition switch itself, or whatever signal wires run to the ABS module. From my understanding the ABS module always has power from the thick red wire, with one or more switch/relay powered wires sending signal to the module. I understand it can be an internal circut board short, but I need to be sure before I start throwing money at a bike that's really not worth it. Again, I appreciate the help.
 

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Discussion Starter #6
After doing more research about the can bus system, I've decided to bypass the ABS servo system. Any photos laying around of brakelines used for the bypass?
 

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I'm in the same boat. I've come to the understanding that we need to keep the that we need to keep the circuit board (or the entire unit) in the bike as it links other systems like the speedo. I think I'm having the under voltage issue as when I put a new battery in or charge it, the ABS works like a champ. That and my brake light stays on so I've been changing my brake micro switches, the rear is new and the problem persists. Ordering the front switch this coming week.
 
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