Ford AF21 Control Module Relearn Procedure

Valve Body Xpress

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There are two relearning procedures that must be followed: Neutral Position Learning and TCM Initial Learning.

Neutral Position Learning Procedure

Neutral Position Learning MUST be performed when a new TCM has been installed!
  1. Apply parking brake and place transmission in Neutral.
  2. Install a scanner and turn the ignition switch on.
  3. Scanner should read Neutral. If scanner does not indicate Neutral, adjust the TCM.
  4. If Neutral is indicated on scan tool, move shifter to park and turn ignition off.
  5. Turn ignition back on and move shifter from park to drive. Scan tool should match each shifter position as shifter is moved to drive.
  6. If scan tool indicates each P-R-N-D-L position, check for trouble codes. If there are no codes, Neutral Position Learning is complete.
  7. If scan tool does not indicate each P-R-N-D-L position, recheck TCM adjustment and check shifter to transmission cable for damage or proper adjustment, then retest starting on Step 3.


TCM Initial Learning Procedure

DO NOT raise transmission fluid temperature by stalling torque converter as internal transmission damage may occur!

  1. Install a scan tool. Clear all trouble codes and set parking brake.
  2. Run the engine to get transmission temperature to between 151-230°F.
  3. With engine idling and transmission at operating temperature, apply foot brake and place transmission in Neutral. Wait 3 seconds, move shifter to D and wait 3 more seconds. Repeat 5 times, and move shifter to Park.
  4. Apply foot brake, move shifter to Neutral and wait 3 seconds. Move shifter to Reverse and wait 3 seconds. Repeat 5 times and move shifter to Park.
  5. Place shifter in drive and release parking brake. Drive vehicle at 25-30% throttle angle until transmission shifts to 6th gear but do not exceed 50 MPH. Release throttle and coast to stop within 60 seconds. Repeat 10 times.
  6. Initial engagements and shift harshness should have decreased. Vehicle may need to be driven more to completely relearn the shift feel that your customer is accustomed to.

TCM Initial Learning Procedure MUST be performed when a new/rebuilt transmission, new/rebuilt valve body or new TCM has been installed, or when the TCM has been replaced or reflashed. In addition, whenever the transmission is rebuilt or valve body is replaced, PCM and TCM should be checked for the latest calibration.


Technical Service Bulletins for the AF21 are as follows:

  • TSB # 05-24-4, dated 12/12/05: harsh/erratic forced downshifts, reprogram PCM & TCM.
  • TSB # 06-24-5, dated 11-15-06: harsh shifting and/or perceived slip engine flair, no trouble codes, reprogram PCM & TCM and/or replace valve body.
  • TSB # 08-24-1 , dated 12/08/08: Same as TSB # 06-24-5
Related Part(s)
Related Unit(s)
Subject(s) Included
  • General Diagnostics and Theory

While Sonnax makes every effort to ensure the accuracy of technical articles at time of publication, we assume no liability for inaccuracies or for information which may become outdated or obsolete over time.

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