1991 K100LT 8v ABS

I've cured a starting problem, (replaced the fuel injection control unit under the seat; bike now runs fine and passed MOT with flying colours), but I am left with a problem with the two red warning lights, (bulb monitoring light and the un-named one at the bottom left of the speedo).

Both lights come on with the ignition and stay lit until I move off and apply the brakes, as expected. However, instead of going out, both then start to flash together, around 1 second on, 1 second off. Normally, this would indicate a faulty tail / brake light, but all the lights work OK.

I will check the connections on the bulb monitoring unit, but is there anything else that can cause this problem?


Simon

That un-named one in the speedo is the ABS light. indicating a ABS fault.

SRD,
First have you got ABS on your bike? If yes, clean the sensor pick up toothed wheels with emery then try it. Flashing indicates the ABS fault.
Most always, the light staying on is the switch cable at the handle bar brake, needs changing. Or the rear one.
Betcha.
Ajays

This Colin's report not mine...It will help you.

ABS2 on early bike]


[list]
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. ]
[/list]
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]

Hi Ajays,

Thanks for the info. For clarification, by "diagnostic connector under the seat", do you mean the flat, 3 pin socket fastened to the top frame tube above the fuel injection control unit, or do you mean the round, white socket in the relay tray?

Regards


Simon

Under seat Righthand side you will see a flat 3 socket with a blank plug in it, Green I think. This is what is used by the dealers for diagnostics.

Follow above instructions.
On Crazy Frogs Download page I believe there is a fault code. With your light you can count the lights to match where the faults is.

If not here it is.





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)
  

Ajays,

Great stuff, I'm sure it will help; many thanks.

I may not get the chance to try this out until Wednesday, but I'll let you know how I get on.


Simon

Hi Simon,
This not a problem, once you have depressed both front and rear brakes sitches, then the warning light will synchronize with ABS warning light.
Start riding your bike, and once you have reached 4 kmh, both lights will turn off unless you have a ABS fault.

Regards,
Denis