Yamaha YP250A 1999 Supplementary Service Manual page 60

[C-5-1] Malfunction code "11" (Front wheel sensor signal does not come in correctly.)
Turn the main switch off once, then turn on again after removing the test coupler adapter.
1) ABS warning light remains going on.
! Defective connection in the front wheel sensor circuit.
S Sensor connector is detached.
S Sensors or leads are disconnected.
S ABS harness sensor circuit is disconnected. ! (Refer to ABS CIRCUIT DIAGRAM)
S ECU connector terminal is disconnected.
2) ABS warning light goes on for 2.0 seconds and goes off.
1 With the front wheel stopped, the rear wheel was rotated for longer than about 20 seconds. This is not a
malfunction.
2 Signal is not generated from the front wheel sensor.
S Sensor is not in place.
S Sensor rotor is defective.
3 Front wheel sensor circuit is short-circuited.
S Sensor or leads are short-circuited.
S Sensor circuit of ABS harness is short-circuited. ! (Refer to ABS CIRCUIT DIAGRAM)
4 Front wheel sensor output drops
S Sensor signal output may drop due to failures on bearings, wheel axle, wheel and sensor housing of front
wheel. Check if there are looseness, distortion or bending with the assembled condition of these compo-
nents.
[C-5-2] Malfunction code "12" (Rear sensor signal does not come in correctly.)
Turn the main switch off once, then turn on again.
1) ABS warning light keeps going on.
! Defective connection in the rear wheel sensor circuit.
S Sensor connector is detached.
S Sensors or leads are disconnected.
S ABS harness sensor circuit is disconnected. ! (Refer to ABS CIRCUIT DIAGRAM)
S ECU connector terminal is disconnected.
2) ABS warning light goes on for 2.0 seconds and goes off.
1 With the rear wheel stopped, the front wheel was rotated at a speed faster than about 11 km/h. This is
not a malfunction.
2 Signal is not generated from the rear wheel sensor.
S Sensor is not in place.
S Sensor rotor defective.
3 Rear wheel sensor circuit is short-circuited.
S Sensor or leads are short-circuited.
S Sensor circuit of ABS harness is short-circuited. ! (Refer to ABS CIRCUIT DIAGRAM)
ANTI-LOCK BRAKE SYSTEM (ABS)
52
CHAS
! [D-3]
! [D-3]
! [D-1]
! [D-3]
! [D-3]
! [D-3]
! [D-4]
! [D-4]
! [D-1]
! [D-4]
! [D-4]
! [D-3]