[RemonLT]

Hey guys,
Here is a new question that I have not yet been able to find in the hall of wissdom.
This concerns a '99 LT that has just given the well-known ABS 1 Hz message on the dashlights. It showed up while driving on the highway, with slightly damp weather. The battery is new and measures 13.3v and the battery terminals are tight. At first the OBD dongle indicated error codes in the hall sensor signal 1 (0335) and signal 2 (0385). After I restarted the engine the error messages disappeared. I have to mention that the enige came to life after starting in two times. I'm going to see the brake fluid reservoir at the back this evening, front is full. Since I have scheduled a serious motorcycle ride next Friday, any help is welcome to take any uncertainties away. If I find anything myself, I will let you know. Thanks in advance...

 

[sailor]

Hey guys,
Here is a new question that I have not yet been able to find in the hall of wissdom.
This concerns a '99 LT that has just given the well-known ABS 1 Hz message on the dashlights. It showed up while driving on the highway, with slightly damp weather. The battery is new and measures 13.3v and the battery terminals are tight. At first the OBD dongle indicated error codes in the hall sensor signal 1 (0335) and signal 2 (0385). After I restarted the engine the error messages disappeared. I have to mention that the enige came to life after starting in two times. I'm going to see the brake fluid reservoir at the back this evening, front is full. Since I have scheduled a serious motorcycle ride next Friday, any help is welcome to take any uncertainties away. If I find anything myself, I will let you know. Thanks in advance...

FIRST: not sure what tool you are using as an "OBD dongle" (as stated in your post above). If you had used a GS911 instead, it does clearly explain in screen that these 2 "hall effect" sensors error codes are normal if engine is not currently running (or if engine was not cranked over before reading codes). Be aware that many of these so-called compatible OBD dongle do NOT work as wel as a GS911 or the dealer's computer for older BMW models (mainly those without CANBUS).

SECOND: on the 1st generation K1200LT having the older ABS2 modulator (without servos) like yours, in most cases the fault comes from either:
A) a weak battery. Even if you see 13.3 volts you may still have a weak battery when you just turn ignition ON (before engine is started).

B) one or both ABS wheel speed sensor having incorrect gap. These ABS2 models are very sensitive and very specific as the gap must be between 0.020 to 0.022 inch (0.45 to 0.55 mm)

C) you should also check for dirt or deposit on either wheel speed sensor surface (toward dented wheel)

D) Since you said "It showed up while driving on the highway, with slightly damp weather", you should also check for a dirty or loose connection upstream from either sensor wires. There has been a few cases reported of damaged ABS speed sensor wire on the rear brake between rear caliper and junction at end of the wire.


NOTE that unlike later models, on ABS2 models like yours the Brake Fluid level is NOT monitored by the system - so In your case the fault is something else. For ABS2 like your, the fault must be erased / reset using a GS911 or the dealer's computer to see if it wil re-appear at next ignition ON cycle (or during next ride).

 

[sailor]

oopss... double-post sorry ;-)
ADMIN please delete this - thank you!

 

[RemonLT]

Thanks very much John. I use MotoScan software (payed version), not all the GS911 options, but does give a nice starting point.

1. Battery cranks fine, no drop in voltage, alternator works fine also.
2. It's getting dark here so i couldn't measure the gap. Will try that tomorrow and also inspect the surface of de ABS ring and clean the sensors.
3. I read about the damaged wires, will check that tomorrow in detail.
4. Brake fluid is fine in front and rear. But if my LT doesn't measure that, I have to seach the issue somewhere else.
5. I've got a wire in the 'connector PIN 21' attached on my LT, so I can and will erase the fault tomorrow to see if it will appear again after I did the checks and cleaning.

Greeting,

Remon

 

[sailor]

Thanks very much John. I use MotoScan software (payed version), not all the GS911 options, but does give a nice starting point.

1. Battery cranks fine, no drop in voltage, alternator works fine also.
2. It's getting dark here so i couldn't measure the gap. Will try that tomorrow and also inspect the surface of de ABS ring and clean the sensors.
3. I read about the damaged wires, will check that tomorrow in detail.
4. Brake fluid is fine in front and rear. But if my LT doesn't measure that, I have to seach the issue somewhere else.
5. I've got a wire in the 'connector PIN 21' attached on my LT, so I can and will erase the fault tomorrow to see if it will appear again after I did the checks and cleaning.

Greeting,

Remon

I taught the scanner (OBD tool) you were using would allow for an ABS fault reset, SO... I had not mention the trick about pin 21 for reset.

Unlike the later iABS system (with servos) when dealing with ABS2 system fault, you need to clear manually EVEN AFTER the cause of the fault has been fixed. For most fault codes the ABS2 system will keep them in memory otherwise - some kind of safety (or scam) to force the owner to go to dealer for a check / reset.

 

[RemonLT]

So, I cleaned the sensors, checked the wiring, fluid and voltage. Everything looked fine. Did the ABS reset with the pin 21 and ground wire on Pin 2. No errorcode on dash anymore. Strange, but maybe it was some small debris.

 

[jzeiler]

That or a momentary weak battery, once triggered the fault stays until cleared. Glad you have it cleared.

 

[RemonLT]

Short update: Just got back from a four day trip, 2000 kilometers without highways, so a lot of braking was needed. Didn't get any new blinking ABS lights on the dash so I do hope is was something small.