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Home >> Mitsubishi >> 2014 >> Lancer ES Sportback >> Repair and Diagnosis >> Brakes >> Traction Control >> Active Stability Control System (ASC) - With Diagnostics - Lancer >> Diagnosis >> Diagnostic Trouble Code Procedures >> DTC C1027: Abnormality in RL wheel speed sensor signal >> Diagnosis

DTC C1027: Abnormality in RL wheel speed sensor signal: Diagnosis

Required Special Tools: 

  1. STEP 1. Using scan tool MB991958, diagnose the CAN bus lines. 

    Use scan tool to diagnose the CAN bus lines.

    Q: Is the check result normal? 

    1. YES:  Go to  Step 3.
    2. NO:  Repair the CAN bus lines (Refer to CAN BUS DIAGNOSTICS TABLE ). On completion, go to Step 2.
  2. STEP 2. DTC recheck after resetting CAN bus lines 

    Q: Is DTC C1027 set? 

    1. YES:  Go to Step 3.
    2. NO:  The procedure is complete.
  3. STEP 3. Using scan tool MB991958, check the DTC 

    Check that the DTC C1020 is also set.

    Q: Is DTC C1020 also set? 

    1. YES:  Perform the diagnosis for the DTC C1020 (Refer to DTC C1020 ABNORMALITY IN RL WHEEL SPEED SENSOR CIRCUIT  ).
    2. NO:  Go to Step 4.
  4. STEP 4. Connector check: A-51 ASC-ECU connector, C-39 intermediate connector, D-15 intermediate connector, F-21 rear wheel speed sensor < LH > connector 

    Q: Is the check result normal? 

    1. YES:  Go to Step 5.
    2. NO:  Repair the defective connector. Then go to  Step 12.
  5. STEP 5. Wiring harness check between A-51 ASC-ECU connector terminal No. 36 and F-21 rear wheel speed sensor < LH > connector terminal No. 1, and between A-51 ASC-ECU connector terminal No. 37 and F-21 rear wheel speed sensor < LH > connector terminal No. 2. 

    Q: Is the check result normal? 

    1. YES:  Go to Step 6.
    2. NO:  Repair the wiring harness. Then go to  Step 12.
  6. STEP 6. Check for wheel speed sensor < RL > installation 

    Check how the wheel speed sensor < RL > is installed (Disconnection of wheel speed sensor < RL >, loose mounting bolt, etc.).

    Q: Is the check result normal? 

    1. YES:  Go to Step 7.
    2. NO:  Reinstall the wheel speed sensor < RL > correctly (Refer to WHEEL SPEED SENSOR  ). Then go to Step 7.
  7. STEP 7. Check for wheel speed sensor < RL > output current 

    Refer to WHEEL SPEED SENSOR OUTPUT CURRENT MEASUREMENT  .

    Q: Is the check result normal? 

    1. YES:  Go to Step 8.
    2. NO:  Replace the wheel speed sensor < RL > (Refer to WHEEL SPEED SENSOR  ). Then go to  Step 11.
  8. STEP 8. Check for wheel bearing looseness 
    NOTE:
    • Loose wheel bearing may increase the gap between the wheel speed sensor < RL > and the wheel speed detection magnet encoder.
    • Check the Rear wheel hub assembly < RL (FWD) > (Refer to WHEEL BEARING PLAY CHECK ).
    • Check the wheel bearing < RL (AWD) > for looseness (Refer to WHEEL BEARING PLAY CHECK ).

    Q: Is the check result normal? 

    1. YES:  Go to Step 9.
    2. NO (FWD):  Replace the rear wheel hub assembly < RL > (Refer to REAR AXLE HUB ASSEMBLY ). Then go to  Step 12.
    3. NO (AWD):  Replace the wheel bearing < RL > (Refer to REAR AXLE HUB ASSEMBLY ). Then go to  Step 12.
  9. STEP 9. Check of wheel speed detection encoder 

    Check the encoder for adhesion of foreign materials or deformation.

    Q: Is the check result normal? 

    1. YES:  Go to Step 10.
    2. NO (Adhesion of foreign materials):  Remove the foreign materials and clean the encoder so as not to disturb the magnetization pattern on it while taking care of the magnet, magnetic substance, and magnetic attraction. Then go to  Step 12.
    3. NO < Deformation (FWD) >:  Replace the rear wheel hub assembly < RL > (Refer to REAR AXLE HUB ASSEMBLY ). Then go to  Step 12.
    4. NO < Deformation (AWD) >:  Replace the wheel bearing < RL > (Refer to REAR AXLE HUB ASSEMBLY ). Then go to  Step 12.
      Fig 1: Identifying Ball Bearing, Magnetic Encoder, Rear Hub And Oil Seal
      G07032560Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
  10. STEP 10. Check whether the DTC is reset. 
    1. Erase the DTC.
    2. Drive the vehicle at 12mph (20 km/h) or higher.
      NOTE: The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12mph (20 km/h) or higher.

    Q: Is DTC C1027 set? 

    1. YES:  Replace the wheel speed sensor < RL > (Refer to WHEEL SPEED SENSOR  ). Then go to Step 11.
    2. NO:  Intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).
  11. STEP 11. Check whether the DTC is reset. 
    1. Erase the DTC.
    2. Drive the vehicle at 12 mph (20 km/h) or higher.
      NOTE: The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12 mph (20 km/h) or higher.

    Q: Is DTC C1027 set? 

    1. YES:  Replace the hydraulic unit (integrated with ASC-ECU) (Refer to HYDRAULIC UNIT  ). Then go to Step 12.
    2. NO:  The procedure is complete.
  12. STEP 12. Check whether the DTC is reset. 
    1. Erase the DTC.
    2. Drive the vehicle at 12 mph (20 km/h) or higher.
      NOTE: The ABS warning light does not turn OFF in some cases unless the vehicle runs at 12 mph (20 km/h) or higher.

    Q: Is DTC C1027 set? 

    1. YES:  Return to  Step 1.
    2. NO:  The procedure is complete.
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