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Home >> Acura >> 2006 >> MDX Base >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transmission >> DTC Troubleshooting >> DTC P0721: Problem in Output Shaft (Countershaft) Speed Sensor Circuit

DTC P0721: Problem in Output Shaft (Countershaft) Speed Sensor Circuit

NOTE:
  • Record all freeze data and review General Troubleshooting Information (see GENERAL TROUBLESHOOTING INFORMATION  ) before you troubleshoot.
  • This code is caused by an electrical circuit problem and cannot be caused by a mechanical problem in the transmission.
  1. Clear the DTC with the HAS.
  2. Check for proper output shaft (countershaft) speed sensor installation (see INPUT SHAFT (MAINSHAFT) SPEED SENSOR REPLACEMENT  ).
  3. Raise the vehicle, make sure it is securely supported, and allow the all four wheels to rotate freely.
  4. Start the engine and turn the VSA off (the light on the VSA OFF switch comes on). Run the engine in the D5 position with engine speed 2,000 RPM or higher for more than 10 seconds. Slow down and stop the wheels.
  5. Monitor the OBD status for P0721 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail.

    Does the result indicate FAILED? 

    1. YES  - Go to step 6.
    2. NO  - Intermittent failure, the system is OK at this time. If the tester indicates NOT COMPLETED, return to step  4 and recheck.
  6. Turn the ignition switch OFF.
  7. Jump the SCS line with the HAS.
  8. Disconnect PCM connector A (73P), and output shaft (countershaft) speed sensor connector.
  9. Check for continuity between PCM connector terminals A39 and body ground, between A40 and body ground, and between A73 and body ground.
    Fig 1: Checking For Continuity Between PCM Connector Terminals A39 And Body Ground
    G03640252Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Go to step 10.
    2. NO  - Repair open in the wires between PCM connector terminals A39, A40, A73, and ground (G101, G102), or repair poor ground (G101, G102), then go to step  30.
  10. Connect PCM connector A (73P).
  11. Turn the ignition switch ON (II).
  12. Measure the voltage between output shaft (countershaft) speed sensor connector terminal No. 1 and body ground.
    Fig 2: Measuring Voltage Between Output Shaft (Countershaft) Speed Sensor Connector Terminal No. 1 And Body Ground
    G03640253Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there about 5 V? 

    1. YES  - Go to step  16.
    2. NO  - Go to step 13.
  13. Turn the ignition switch OFF.
  14. Disconnect PCM connector A (73P).
  15. Check for continuity between PCM connector terminal A7 and output shaft (countershaft) speed sensor connector terminal No. 1.
    Fig 3: Checking For Continuity Between PCM Connector Terminal A7 And Output Shaft (Countershaft) Speed Sensor Connector Terminal No. 1
    G03640254Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Check for loose or poor connections at PCM connector terminal A7. If the connection is OK, update the PCM if it does not have the latest software, or substitute a known-good PCM (see PCM UPDATING AND SUBSTITUTION FOR TESTING  ), then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
    2. NO  - Repair open in the wire between PCM connector terminal A7 and the output shaft (countershaft) speed sensor, then go to step  30.
  16. Turn the ignition switch OFF.
  17. Disconnect PCM connector A (73P).
  18. Check for continuity between output shaft (countershaft) speed sensor connector terminal No. 2 and body ground.
    Fig 4: Checking For Continuity Between Output Shaft (Countershaft) Speed Sensor Connector Terminal No. 2 And Body Ground
    G03640255Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Repair short to ground in the wire between PCM connector terminal A47 and output shaft (countershaft) speed sensor connector, then go to step  30.
    2. NO  - Go to step 19.
  19. Check for continuity between PCM connector terminal A8 and the No. 3 terminal of the output shaft (countershaft) speed sensor connector.
    Fig 5: Checking For Continuity Between PCM Connector Terminal A8 And No. 3 Terminal Of Output Shaft (Countershaft) Speed Sensor Connector
    G03640256Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Go to step 20.
    2. NO  - Repair open in the wire between the output shaft (countershaft) speed sensor connector and PCM connector terminal A8, then go to step  30.
  20. Connect PCM connector A (73P).
  21. Turn the ignition switch ON (II).
  22. Measure the voltage between output shaft (countershaft) speed sensor connector terminals No. 2 and No. 3.
    Fig 6: Measuring Voltage Between Output Shaft (Countershaft) Speed Sensor Connector Terminals No. 2 And No. 3
    G03640257Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there about 5 V? 

    1. YES  - Go to step  26.
    2. NO  - Go to step 23.
  23. Turn the ignition switch OFF.
  24. Disconnect PCM connector A (73P).
  25. Check for continuity between PCM connector terminal A47 and output shaft (countershaft) speed sensor connector terminal No. 2.
    Fig 7: Checking For Continuity Between PCM Connector Terminal A47 And Output Shaft (Countershaft) Speed Sensor Connector Terminal No. 2
    G03640258Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Update the PCM if it does not have the latest software, or substitute a known-good PCM (see PCM UPDATING AND SUBSTITUTION FOR TESTING  ), then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
    2. NO  - Repair open in the wire between PCM connector terminal A47 and the output shaft (countershaft) speed sensor, then go to step  30.
  26. Connect the output shaft (countershaft) speed sensor connector.
  27. Clear the DTC with the HAS.
  28. Start the engine and turn the VSA off (the light on the VSA OFF switch comes on). Run the engine in the D5 position with engine speed 2,000 RPM or higher for more than 10 seconds. Slow down and stop the wheels.
  29. Monitor the OBD status for P0721 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail.

    Does the result indicate FAILED? 

    1. YES  - Replace the output shaft (countershaft) speed sensor (see INPUT SHAFT (MAINSHAFT) SPEED SENSOR REPLACEMENT  ), then go to step  30.
    2. NO  - Update the PCM if it does not have the latest software, or substitute a known-good PCM (see PCM UPDATING AND SUBSTITUTION FOR TESTING  ), then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
  30. Clear the DTC with the HAS.
  31. Start the engine and turn the VSA off (the light on the VSA OFF switch comes on). Run the engine in the D5 position with engine speed 2,000 RPM or higher for more than 10 seconds. Slow down and stop the wheels.
  32. Monitor the OBD status for P0721 in the DTCs/Freeze Data in A/T Mode Menu for a pass/fail.

    Does the result indicate PASSED? 

    1. YES  - Troubleshooting is complete.
    2. NO  - Return to step  1 and recheck.
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