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Pinpoint Test L: DTC C1991 - Module Calibration Failure

NOTE: The stability assist lamp flashes when a system calibration is required. Calibration is required after certain diagnostic trouble codes (DTCs) are cleared.
NOTE: Make sure the vehicle is not on a hoist and is sitting on level ground before carrying out stability assist module calibration.
  1. L1 CHECK FOR DTCs 
    • Connect the diagnostic tool.
    • Key in ON position.
    • Retrieve the recorded results from the smart junction box (SJB) self-test.
    • Is any other DTC retrieved with C1991? 
    1. YES  : Go to the Anti-Lock Brake System (ABS) Diagnostic Trouble Code (DTC) Index.

      Some of the pinpoint tests recommend ABS module calibration prior to any further diagnostics. In this case, go to  L2 .

    2. NO  : Go to  L2.
  2. L2 CALIBRATE THE ABS MODULE  
    • Key in START position.
      • NOTE: Be sure to rotate the steering wheel lock-to-lock during the calibration of the ABS system.
      NOTE: To successfully carry out the ABS module calibration, the transmission must be in PARK, the engine must be running and there must be no brake pedal input.
    • Carry out the ABS module calibration per the scan tool instructions.
    • Does the calibration complete for all of the stability assist sensors, and does the stability assist lamp stop flashing and turn off? 
    1. YES  : Go to  L3.
    2. NO  : Go to  L4.

      Some concerns will not allow the calibration to complete. If sent here from another pinpoint test, return to that pinpoint test for further diagnostics.

  3. L3 CLEAR DTC C1991 
    NOTE: Clear DTC C1991 after completing the calibration.
    • Connect the diagnostic tool.
    • Key in ON position.
    • CLEAR the DTC.
    • Does the DTC clear? 
    1. YES  : TEST DRIVE the vehicle. REPEAT the self-test.

      If sent here from another pinpoint test, return to that pinpoint test for further diagnostics.

    2. NO  : Go to  L4.
  4. L4 MONITOR THE STEERING WHEEL ROTATION SENSOR PIDs 
    • Key in ON position.
    • Monitor the ABS module steering wheel rotation sensor PIDs while rotating the steering wheel clockwise and counterclockwise.
    • Are the 2 steering wheel rotation sensor PID values switching as the wheel rotates? 
    1. YES  : Go to Pinpoint Test G .
    2. NO  : Go to Pinpoint Test F .
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