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Home › Subaru › 2001 › Forester Base › Repair and Diagnosis › Brakes › Traction Control › Anti-Lock Braking System - Diagnostics › Diagnostics Chart With Trouble Code By Abs Warning Light › Code 29: Abnormal Abs Sensor Signal (Any One Of Four)

Code 29: Abnormal Abs Sensor Signal (Any One Of Four)

DIAGNOSIS: 

TROUBLE SYMPTOM: 

WIRING DIAGRAM: 

Fig 1: Wiring Diagram
G02010878
  1. 8J1: CHECK IF THE WHEELS HAVE TURNED FREELY FOR A LONG TIME. 

    CHECK: Check if the wheels have been turned freely for more than one minute, such as when the vehicle is jacked-up, under full-lock cornering or when tire is not in contact with road surface. 

    1. YES:  The ABS is normal. Erase the trouble code.
      NOTE: When the wheels turn freely for a long time, such as when the vehicle is towed or jacked-up, or when steering wheel is continuously turned all the way, this trouble code may sometimes occur.
    2. NO:  Go to step 8J2. 
  2. 8J2: CHECK TIRE SPECIFICATIONS. 

    CHECK: Are the tire specifications correct? 

    1. YES:  Go to step 8J3. 
    2. NO:  Replace tire.
  3. 8J3: CHECK WEAR OF TIRE. 

    CHECK: Is the tire worn excessively? 

    1. YES:  Replace tire.
    2. NO:  Go to step 8J4. 
  4. 8J4: CHECK TIRE PRESSURE. 

    CHECK: Is the tire pressure correct? 

    1. YES:  Go to step 8J5. 
    2. NO:  Adjust tire pressure.
  5. 8J5: CHECK INSTALLATION OF ABS SENSOR. 

    Tightening torque: 

    1. 32+/-10 N.m (3.3+/-1.0 kg-m, 24+/-7 ft-lb) 

    CHECK: Are the ABS sensor installation bolts tightened securely? 

    1. YES:  Go to step 8J6. 
    2. NO:  Tighten ABS sensor installation bolts securely.
  6. 8J6: CHECK INSTALLATION OF REAR TONE WHEEL. 

    Tightening torque: 

    1. 13+/-3 N.m (1.3+/-0.3 kg-m, 9+/-2.2 ft-lb) 

    CHECK: Are the rear tone wheel installation bolts tightened securely? 

    1. YES:  Go to step 8J7. 
    2. NO:  Tighten rear tone wheel installation bolts securely.
  7. 8J7: CHECK ABS SENSOR GAP. 

    Measure tone wheel to pole piece gap over entire perimeter of the wheel.

    Fig 2: Measuring Tone Wheel To Pole Piece Gap Over Entire Perimeter Of Wheel
    G02010879
    Fig 3: Specifications Tone Wheel To Pole Piece Gap
    G02010880

    CHECK: Is the gap within the specifications? 

    1. YES:  Go to step 8J8. 
    2. NO:  Adjust the gap.
    NOTE: Adjust the gap using spacer (Part No. 26755AA000). If spacers cannot correct the gap, replace worn sensor or worn tone wheel.
  8. 8J8: PREPARE OSCILLOSCOPE. 

    CHECK: Is an oscilloscope available? 

    1. YES:  Go to step 8J9. 
    2. NO:  Go to step  8J10: CHECK CONTAMINATION OF ABS SENSOR OR TONE WHEEL .
  9. 8J9: CHECK ABS SENSOR SIGNAL. 
    1. Raise all four wheels of ground.
    2. Turn ignition switch to OFF.
    3. Connect the oscilloscope to the connector.
    4. Turn ignition switch to ON.
    5. Rotate wheels and measure voltage at specified frequency.
    NOTE: When this inspection is completed, the ABSCM & H/U sometimes stores the trouble code 29.

    Connector & terminal 

    1. (B100) No. 5 (+) - No. 14 (-) (Front RH): 
    2. (B100) No. 7 (+) - No. 16 (-) (Front LH): 
    3. (F55) No. 6 (+) - No. 7 (-) (Rear RH): 
    4. (F55) No. 1 (+) - No. 2 (-) (Rear LH): 
    Fig 4: Measuring Voltage At Specified Frequency While Rotating Wheels
    G02010881

    CHECK: Is oscilloscope pattern smooth, as shown in figure? 

    1. YES:  Go to step  8J13: CHECK ABSCM & H/U .
    2. NO:  Go to step 8J10. 
  10. 8J10: CHECK CONTAMINATION OF ABS SENSOR OR TONE WHEEL. 

    Remove disc rotor from hub.

    CHECK: Is the ABS sensor pole piece or the tone wheel contaminated by direct or other foreign matter? 

    1. YES:  Thoroughly remove dirt or other foreign matter.
    2. NO:  Go to step 8J11. 
  11. 8J11: CHECK DAMAGE OF ABS SENSOR OR TONE WHEEL. 

    CHECK: Are there broken or damaged teeth in the ABS sensor pole piece or the tone wheel? 

    1. YES:  Replace ABS sensor or tone wheel.
    2. NO:  Go to step 8J12. 
  12. 8J12: CHECK HUB RUNOUT. 

    Measure hub runout.

    CHECK: Is the runout less than 0.05 mm (0.0020 in)? 

    1. YES:  Go to step 8J13. 
    2. NO:  Repair hub.
  13. 8J13: CHECK ABSCM & H/U. 
    1. Turn ignition switch to OFF.
    2. Connect all connectors.
    3. Erase the memory.
    4. Perform inspection mode.
    5. Read out the trouble code.

    CHECK: Is the same trouble code as in the current diagnosis still being output? 

    1. YES:  Replace ABSCM & H/U, see ABS CONTROL MODULE AND HYDRAULIC CONTROL UNIT (ABSCM & H/U)  .
    2. NO:  Go to step 8J14. 
  14. 8J14: CHECK ANY OTHER TROUBLE CODES APPEARANCE. 

    CHECK: Are other trouble codes being output? 

    1. YES:  Proceed with the diagnosis corresponding to the trouble code.
    2. NO:  A temporary poor contact.
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