ABS - Module Replacement Service Tip
TSB 04-12-56/01/04
DIAGNOSTIC TROUBLE CODE (DTC) C1991 (MODULE
CALIBRATION FAILURE) - ANTI-LOCK BRAKE,
ADVANCED TRAC, INTERACTIVE VEHICLE
DYNAMICS (IVD), TRACTION CONTROL SYSTEM -
SERVICE TIP
FORD: 2004-2005 Freestar
MERCURY: 2004-2005 Monterey
ISSUE
When replacing the ABS module a code C1991 will be set. This is due to the new module not being calibrated. Proper calibration procedures must be followed to successfully clear the C1991. The new ECU will not complete a successful module calibration if other codes are present, and will keep resetting code C1991. DTC C1991 will be set if:
^ Other anti-lock brake system, traction control/IVD related codes are present during the calibration process.
^ Calibration setup criteria are not met.
^ Module is not calibrated.
ACTION
All other ABS related system conditions and/or DTC's must be resolved before module replacement and module calibration. If the vehicle exhibited a condition and trouble code related to pressure transducer, YAW sensor, brake booster, or steering angle sensor, perform appropriate pinpoint tests and diagnostics. Repair any wiring, connector, and/or sensor issues before module replacement. After the booster, SWA, YAW/LAT, or ECU has been replaced, the ECU will need to be calibrated. Refer to the following Service Procedure.
SERVICE PROCEDURE
Freestar/Monterey module calibration can be performed using the NGS or WDS scan tools.
MODULE CALIBRATION USING WDS
With the brake pedal released, select the following:
1. Toolbox.
2. Chassis.
3. Braking.
MERCURY:
2004-2005 Monterey
4. IVD Initialization Sequence.
5. Ensure that requirements on screen are met for the input you are about to calibrate, then press Confirm.
6. Select YAW Rate/Lateral Acceleration Calibration and follow on-screen prompts.
YAW Sensor Calibration requirements
^ Vehicle in park.
^ Key on.
^ Engine not running.
^ Vehicle on level surface.
7. Select Brake Booster/Steering Wheel Angle Calibration and follow on-screen prompts.
Steering Angle Sensor Calibration requirements
^ Engine running.
^ Turn steering lock to lock.
EAS Booster Calibration requirements
^ Vehicle in park.
^ Engine running.
^ Brake not applied.
MODULE CALIBRATION USING THE NGS
1. Use NGS green service card version 12.4 or greater.
2. Select new vehicle "2004 Freestar/Monterey".
3. Main menu trigger on "Service Bay Functions".
4. Trigger on "ABS".
5. Trigger on "IVD Calibration".
6. NGS message indicates "Prepare Vehicle For Test/Function", ensure that the following requirements are met:
^ Vehicle is on level surface.
^ Start the vehicle and let idle.
^ Steering wheel is centered.
a. Push the trigger button.
7. NGS will automatically go through calibration process steps 7a and 7b, Step 7c must be performed manually.
a. Calibrates YAW/LAT Sensor Cluster.
b. Proceeds to Booster Learn.
c. Steering Wheel Angle Sensor, MANUALLY turn steering wheel full left and right (lock to lock).
NOTE
WHEN THE CALIBRATION PROCEDURE PASSES A MESSAGE WILL APPEAR INDICATING "VEHICLE CALIBRATION COMPLETE".
8. Press cancel to back out to main menu, turn vehicle off, restart vehicle.
9. Use the NGS red diagnostic card and clear codes.
10. Road test the vehicle to verify fix.
NOTE
IF NGS DISPLAYS A MESSAGE INDICATING: "DETERMINING ABS PROTOCOL- PLEASE WAIT" OR "FAILED BOOSTER LEARN" DURING THE AUTOMATIC CALIBRATION PROCESS, OR NGS KEEPS CANCELING THE CALIBRATION PROCESS, THIS MEANS THERE IS A SYSTEM FAULT/CODE PRESENT AND/OR THE ORIGINAL CONDITION HAS NOT BEEN RESOLVED.
WARRANTY STATUS:
Eligible Under Provisions Of New Vehicle Limited Warranty Coverage
DEALER CODING
CONDITION
BASIC PART NO. CODE
2B373 42
Disclaimer