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Home >> Acura >> 2004 >> TSX Standard >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 1 (Automatic Transmission) >> DTC Troubleshooting >> DTC P0721: Problem in Output Shaft (Countershaft) Speed Sensor Circuit; DTC P0722: Problem in Output Shaft (Countershaft) Speed Sensor Circuit (No Signal Input)
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DTC P0721: Problem in Output Shaft (Countershaft) Speed Sensor Circuit; DTC P0722: Problem in Output Shaft (Countershaft) Speed Sensor Circuit (No Signal Input)

WARNING: This page is about a different variant/trim than selected.
NOTE:
  • Before you troubleshoot, record all freeze data and any on-board snapshot, and review General Troubleshooting Information (see GENERAL TROUBLESHOOTING INFORMATION  ).
  • This code is caused by an electrical circuit problem and cannot be caused by a mechanical problem in the transmission.
  1. Turn the ignition switch to ON (II).
  2. Clear the DTC with the HDS.
  3. Check for proper output shaft (countershaft) speed sensor installation (see INPUT SHAFT (MAINSHAFT) SPEED SENSOR REPLACEMENT  ).
  4. Raise the front of the vehicle, make sure it is securely supported, and allow the front wheels to rotate freely. Or raise the vehicle on a lift.
  5. Start the engine, disable the VSA by pressing the VSA OFF switch, run the vehicle with the shift lever in D with engine speed 2,000 rpm or higher for at least 10 seconds. Slowdown and stop the wheels.
  6. Monitor the OBD STATUS for P0721 or P0722 in the DTCs MENU with the HDS.

    Does the screen indicate FAILED? 

    YES  - Go to step 7.

    NO  - If the screen indicates PASSED, intermittent failure, the system is OK at this time. Check for poor connections or loose terminals between the output shaft (countershaft) speed sensor and the PCM. If the screen indicates NOT COMPLETED, go to step  5.

  7. Turn the ignition switch to LOCK (0).
  8. Jump the SCS line with the HDS.
  9. Disconnect PCM connector A (31P) and the output shaft (countershaft) speed sensor connector.
  10. Check for continuity between PCM connector terminal A8 and body ground, and between PCM connector terminal A9 and body ground.
    Fig 1: Checking Continuity Between PCM Connector Terminal A8 And A9 Body Ground
    G05491251Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Go to step 11.

    NO  - Repair open in the wires between PCM connector terminals A8, A9, and ground (G101), or repair poor ground (G101), then go to step  31.

  11. Connect PCM connector A (31P).
  12. Turn the ignition switch to ON (II).
  13. Measure the voltage between output shaft (countershaft) speed sensor connector terminal No. 1 and body ground.
    Fig 2: Measuring Voltage Between Output Shaft Speed Sensor Connector Terminal 1 And Body Ground
    G05491252Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there about 5 V? 

    YES  - Go to step 14.

    NO  - Go to step  26.

  14. Turn the ignition switch to LOCK (0).
  15. Disconnect PCM connector A (31P).
  16. Check for continuity between output shaft (countershaft) speed sensor connector terminal No. 2 and body ground.
    Fig 3: Checking Continuity Between Output Shaft Speed Sensor Connector Terminal 2 And Body Ground
    G05491253Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Repair short to body ground in the wire between PCM connector terminal A18 and the output shaft (countershaft) speed sensor, then go to step  31.

    NO  -

    • '04-05 models: Go to step 17.
    • '06-08 models: Go to step  18.

  17. Check for continuity between output shaft (countershaft) speed sensor connector terminal No. 3 and body ground.
    Fig 4: Checking Continuity Between Output Shaft Speed Sensor Connector Terminal 3 And Body Ground
    G05491254Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Go to step  19.

    NO  - Repair open in the wire between the output shaft (countershaft) speed sensor and ground (G101), repair poor ground (G101), then go to step  31.

  18. Check for continuity between output shaft (countershaft) speed sensor connector terminal No. 3 and PCM connector terminal A23.
    Fig 5: Checking Continuity Between Output Shaft Speed Sensor Connector Terminal 3 And PCM Connector Terminal A23
    G05491255Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Go to step 19.

    NO  - Repair open in the wire between the output shaft (countershaft) speed sensor and PCM connector terminal A23, then go to step  31.

  19. Connect PCM connector A (31P).
  20. Turn the ignition switch to ON (II).
  21. Measure the voltage between output shaft (countershaft) speed sensor connector terminals No. 2 and No. 3.
    Fig 6: Measuring Voltage Between Output Shaft Speed Sensor Connector Terminals 2 And 3
    G05491256Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there about 5 V? 

    YES  - Go to step 22.

    NO  - Go to step  30.

  22. Connect the output shaft (countershaft) speed sensor connector.
  23. Measure the voltage between PCM connector terminals A18 and A9.
    Fig 7: Measuring Voltage Between PCM Connector Terminals A18 And A9
    G05491257Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there 0 V or about 5 V? 

    YES  - Go to step 24.

    NO  - Replace the output shaft (countershaft) speed sensor (see INPUT SHAFT (MAINSHAFT) SPEED SENSOR REPLACEMENT  ), then go to step  31.

  24. Shift the shift lever to P. Start the engine, and let it idle.
  25. Shift to D, and measure the voltage between PCM connector terminals A18 and A9.
    Fig 8: Measuring Voltage Between PCM Connector Terminals A18 And A9
    G05491258Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there 1.5-3.5 V? 

    YES  - Go to step  37.

    NO  - Replace the output shaft (countershaft) speed sensor (see INPUT SHAFT (MAINSHAFT) SPEED SENSOR REPLACEMENT  ), then go to step  31.

  26. Measure the voltage between PCM connector terminals A20 and A9.
    Fig 9: Measuring Voltage Between PCM Connector Terminals A20 And A9
    G05491259Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there about 5 V? 

    YES  - Repair open in the wire between PCM connector terminal A20 and the output shaft (countershaft) speed sensor, then go to step  31.

    NO  - Go to step 27.

  27. Turn the ignition switch to LOCK (0).
  28. Disconnect PCM connector A (31P).
  29. Check for continuity between PCM connector terminal A20 and body ground.
    Fig 10: Checking Continuity Between PCM Connector Terminal A20 And Body Ground
    G05491260Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Repair short to body ground in the wire between PCM connector terminal A20 and the output shaft (countershaft) speed sensor, then go to step  31.

    NO  - Go to step  37.

  30. Measure the voltage between PCM connector terminals A18 and A9.
    Fig 11: Measuring Voltage Between PCM Connector Terminals A18 And A9
    G05491261Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there about 5 V? 

    YES  - Repair open in the wire between PCM connector terminal A18 and the output shaft (countershaft) speed sensor, then go to step 31.

    NO  - Go to step  37.

  31. Reconnect all connectors.
  32. Turn the ignition switch to ON (II).
  33. Clear the DTC with the HDS.
  34. Start the engine, disable the VSA by pressing the VSA OFF switch, run the vehicle with the shift lever in D with engine speed 2,000 rpm or higher for at least 10 seconds. Slow down and stop the wheels.
  35. Check for DTCs with the HDS.

    Is DTC P0721 or P0722 indicated? 

    YES  - Check for poor connections or loose terminals between the output shaft (countershaft) speed sensor and the PCM, then go to step  1.

    NO  - Go to step 36.

  36. Monitor the OBD STATUS for P0721 or P0722 in the DTCs MENU with the HDS.

    Does the screen indicate PASSED? 

    YES  - Troubleshooting is complete. If any other DTCs were indicated in step  35, go to the INDICATED DTCS TROUBLESHOOTING .

    NO  - If the screen indicates FAILED, check for poor connections or loose terminals between the output shaft (countershaft) speed sensor and the PCM, then go to step  1. If the screen indicates NOT COMPLETED, go to step  34.

  37. Update the PCM if it does not have the latest software (see UPDATING THE PCM  ), or substitute a known-good PCM (see SUBSTITUTING THE PCM  ).
  38. Start the engine, disable the VSA by pressing the VSA OFF switch, run the vehicle with the shift lever in D with engine speed 2,000 rpm or higher for at least 10 seconds. Slow down and stop the wheels.
  39. Check for DTCs with the HDS.

    Is DTC P0721 or P0722 indicated? 

    YES  - Check for poor connections or loose terminals between the output shaft (countershaft) speed sensor and the PCM. If the PCM was updated, substitute a known-good PCM (see SUBSTITUTING THE PCM  ), then go to step  38. If the PCM was substituted, go to step  1.

    NO  - Go to step 40.

  40. Monitor the OBD STATUS for P0721 or P0722 in the DTCs MENU with the HDS.

    Does the screen indicate PASSED? 

    YES  - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM; '04-05 models (see '04-05 MODELS ), '06-08 models (see '06-08 MODELS ). If any other DTCs were indicated in step  39, go to the INDICATED DTCS TROUBLESHOOTING .

    NO  - If the screen indicates FAILED, check for poor connections or loose terminals between the output shaft (countershaft) speed sensor and the PCM. If the PCM was updated, substitute a known-good PCM (see SUBSTITUTING THE PCM  ), then go to step  38. If the PCM was substituted, go to step  1. If the screen indicates NOT COMPLETED, go to step  38.

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