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Clearing BMW ABS errors

8/15/2010

BMW ABS faults and resetting

Faults

ABS1

ABS1 was only used on older K bikes. A fault is indicated by the ABS light and the bulb monitor flashing in unison. The bulb monitor will be on continuously until the system has verified operation of both brake switches and both bulb filaments (taillignt and brake light) and then it extinguishes and becomes the second ABS light. The primary ABS light (and the monitor light, once its test is complete) will flash in unison until the bike moves off. If they continue to flash in unison after that, there is a fault. You will probably get a fault #7 upon startup after you have left the battery disconnected for a period of time.

ABS2

ABS2 on the K11 uses the same two lights as ABS1: the ABS light and the bulb monitor light. On Oilheads and K12s, it has two distinct lights of its own. At key-on, the two lights will flash together and continue to do so until the self-test is complete (which doesn't happen until you start to ride away), at which time they extinguish. If the self-test fails, they will begin to flash alternately. The exact moment when the fault happens will help you know what caused it: if it happens before you start the engine it is an item that is tested at power-up. If it fails when you start the engine, it is almost certainly low battery voltage. And if it fails when you ride away, it's probably a modulator or a wheel speed sensor.

Sometimes ABS2 will fault without showing a fault code.

Integral ABS (iABS)

Faults are displayed by use of the GEN and ABS lights. At this time I don't know which are persistent.

Resetting:

(mostly from the IBMWR tech pages)

Resetting ABS1

  • Locate the diagnostic connector on the right frame rail, under the seat. Remove it from the blanking plug.
  • Insert one end of 20 cm wire into the middle socket of this connector.
  • Ground the other end firmly to a metal bolt in the area (and keep grounded).
  • Hold the ABS button down as you turn the ignition on. You should see the lights flash together as normal.
  • Keep holding the ABS button down for about 8 seconds. The ABS light will stay on solid.
  • Release the ABS button.
  • Turn off ignition, remove wire.

Resetting ABS2

  • Locate the diagnostic connector under the seat. Remove it from the blanking plug.
  • Insert one end of 20 cm wire into the middle socket of this connector.
  • Ground the other end firmly to a metal bolt in the area (and keep grounded).
  • Turn on ignition. You should see the lights flash alternately.
  • Hold ABS button down for about 8 seconds. The bottom ABS light will stay on, and the top one off.
  • Release the ABS button. If you have successfully reset the ABS, both ABS lights will come on. If you have failed to count to 8, or your ground is not good, the top ABS light will stay off.
  • Turn off ignition, remove wire.

Resetting R1150GS ABS2

  • Locate the round diagnostic connector on top of the airbox
  • With a wire, ground the brown/blue stripe wire (pin #2) and keep it grounded.
  • Turn the ignition on
  • Hold the ABS button down for about 8 seconds.
  • Release the ABS button.
  • Turn off the ignition, remove wire.

Note: the K1200, R1200C and R1100S use the same ABS2 units as the 1150GS, but there is no ABS switch to use for the reset procedure.  If you can access pin #21 on the ABS unit, you can ground it to achieve the same effect as having the ABS button. Pin #21 will be on the large connector to the ABS unit. This procedure has been successful on an R1100S.

Fault Codes

ABS1 and ABS2 fault codes

Info on diagnosing ABS1 and ABS2 faults is described by Brian Curry in great detail on the IBMWR K-tech pages. In a nutshell, by putting a readout light between the ABS pin and ground you can get a blink code when the bike is on. All codes except 5 seem to be persistent (needing reset by this procedure). There is also a BMW document, part 01 71 9 798 811 (5/90), that you may be able to locate which is for troubleshooting ABS.

  • 1. front pressure modulator
  • 2. rear pressure modulator
  • 3. front wheel speed sensor
  • 4. rear wheel speed sensor
  • 5. battery voltage too low
  • 6. ABS relay
  • 7. ABS control unit
  • 8. sensor gap front or rear, or other outsude influence
  • 9. <unknown, but seems to exist>
  • 16. reportedly "Failed plunger test" (also seems to be persistent)

iABS fault codes

These should be listed on a sticker supplied with the bike.

  • Gen OFF, ABS ON = Only residual braking in both circuits.
  • Gen OFF, ABS flashes at 1Hz = ABS not available. Pull-away test not completed.
  • Gen OFF, ABS flashes at 4Hz = Only residual braking function available in both circuits.
  • Gen ON, ABS off = rear light/brake light defective.
  • Gen ON, ABS flashes at 1 Hz = At least one brake circuit without ABS.
  • Gen ON, ABS flashes at 4Hz =At least one brake circuit in residual braking function mode.
  • Gen AND ABS flashing alternately at 1Hz = Fluid level in Intergral ABS too low.Low-voltage

ABS2 differences between models

The same basic ABS2 control unit is used on the K1100 and nearly all 5-speed R1100 models.  There was an early version that might have only been used on the R1100RS, then the same unit is used on all ABS2 bikes until Motronic 2.4. The only difference seems to be in the wiring; according to my diagram different bikes have different combinations of pins 9, 10, 22 and 23 grounded. Each unit also has a coding number that supposedly can be read out from the center pin (like the fault codes) when the key is on and the ABS button is pushed (although I cannot get this to happen on my R11RS or R11GS):

Model Coding Pin 9 Pin 22 Pin 10 Pin 23
+8 +4 +2 +1
R1100R, R850R 12 X X    
R1100RT 8 X      
R1100GS 4   X    
R1100RS (93, 94) 2     X  
R1100RS (95-) 1       X
K1100LT 11 X   X X
K1100RS 7   X X X

This coding might only apply to the 34 51 2 331 935 ABS unit. Other units can be damaged or will not respond to the recoding.

  • 34 51 2 306 300 - early model. Might NOT be usable on bikes other than the R11RS! Superseded by...
  • 34 51 2 331 935 - R11RS, R11RT, R11R, R850R, R11GS, K11RS, K11LT (MA2.2)
  • 34 51 2 325 868 - Remanufactured version of 2 331 935
  • 34 51 2 331 637 - R11S, K12RS, R1150GS, R1200C (MA2.4)
  • 34 51 2 333 232 -K12LT

To disable ABS on the R1100GS, you hold the ABS button down whilst turning the ignition on.  This should leave one ABS light lit, which will flash as you ride. By altering the wiring harness, one might be able to make the ABS selectable on the other R1100 models. 

 

 

(republished from largiader.com )