Pinpoint Test M: DTC C1991 - Module Calibration Failure

WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: The stability assist lamp will flash when a system calibration is required. Calibration is required after certain 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.

M1 CHECK FOR DTCs
- Connect the diagnostic tool.
- Key in ON position.
- Using the recorded results from the SJB self-test:
- Is any other DTC retrieved with C1998?
Yes

GO to the appropriate pinpoint test for the DTC. Some of the pinpoint tests recommend ABS module calibration prior to any further diagnostics; in this case, GO to M2.

No

GO to M2.
M2 ABS MODULE CALIBRATION
- Connect the diagnostic tool.
- Start the engine.
- Carry out the ABS module calibration per the diagnostic tool instructions.
- Did the calibration complete for all of the stability assist sensors; and did the stability assist lamp stop flashing and go off?
Yes

GO to M3.

No

GO to M4.

Some concerns will cause the calibration not to complete. If sent here from another pinpoint test, return to that pinpoint test for further diagnostics.
M3 CLEAR DTC C1991
NOTE: Clear DTC C1991 after completing the calibration.
- Connect the diagnostic tool.
- Key in ON position.
- CLEAR the DTCs.
- Did the DTC clear?
Yes

TEST DRIVE the vehicle. REPEAT the self-test.

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

No

GO to M4.
M4 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 two steering wheel rotation sensor PID values switching as the wheel rotates?
Yes

GO to PINPOINT TEST H .

No

GO to PINPOINT TEST G .