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Pinpoint Test O: DTC C1991 - Module Calibration Failure

WARNING: This page is about a different car, the 2008 Ford RV Cutaway, 2008 Ford Econoline, 2008 Ford E450 Super Duty, and 2008 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: The stability assist active/fail lamp flashes when a system calibration is required. Calibration is required after certain DTCs are cleared.
NOTE: The vehicle must be on level ground, at a complete standstill and not  on a hoist while carrying out the calibration procedure. Any vehicle movement will result in calibration failure.
  1. O1 CHECK FOR ABS MODULE DTCs 
    • Connect the diagnostic tool.
    • Key in ON position.
    • Retrieve the recorded DTCs.
    • Is any other DTC retrieved with C1991? 
    1. YES  : DIAGNOSE all other DTCs first. Go to the ABS Module DTC Chart.

      Some of the pinpoint tests recommend ABS module calibration prior to any further diagnostics. In this case, go to  O2.

    2. NO  : Go to  O2.
  2. O2 CALIBRATE THE ABS MODULE  
    • Enter the following diagnostic mode on the diagnostic tool: IVD (ESC) Initialization Sequence
      • NOTE: Be sure to rotate the steering wheel lock-to-lock during the calibration of the ABS module.
    • Carry out the IVD (ESC) initialization sequence per the scan tool instructions.
    • Does the IVD (ESC) initialization sequence complete for all of the stability assist sensors and does the stability assist active/fail lamp stop flashing and turn off? 
    1. YES  : Go to  O3.
    2. NO  : Go to  O4.

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

  3. O3 CLEAR DTC C1991 
    • Using the scan tool, 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  O4.
  4. O4 MONITOR THE STEERING WHEEL ANGLE POSITION (SWA POS) PID 
    • Enter the following diagnostic mode on the diagnostic tool: DataLogger ABS Module
    • Monitor the SWA POS PID while rotating the steering wheel clockwise and counterclockwise very slowly.
    • Do the PIDs move in intervals of 4.5 degrees? 
    1. YES  : Go to Pinpoint Test L .
    2. NO  : Go to Pinpoint Test K .
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