P0721

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

NOTE: Before You troubleshoot, record all freeze data and any on-board snapshot, and review General Troubleshooting Information. 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 HDS.
2. Check for proper output shaft (countershaft) speed sensor installation.
3. 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 hoist.
4. Start the engine, run the vehicle in the D 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?
YES - Go to step 6.
NO - Intermittent failure, the system is OK at this time. Check for loose or poor connections at the PCM and output shaft (countershaft) speed sensor connectors. If the HDS indicates NOT COMPLETED, return to step 4 and recheck.

6. Turn the ignition switch OFF.
7. Jump the SCS line with the HDS.
8. Disconnect PCM connector C (44P).





9. Check for continuity between PCM connector terminal C40 and body ground, and between terminal C44 and body ground.
Is there continuity?
YES - Go to step 10.
NO - Repair open in the wires between PCM connector terminals C40, C44, and ground (G101), or repair a poor ground (G101), then go to step 32.

10. Connect PCM connector C (44P).
11. Disconnect the output shaft (countershaft) speed sensor connector.
12. Turn the ignition switch ON (II).





13. Measure voltage between output shaft (countershaft) speed sensor connector terminal No. 1 and body ground.
Is there about 5 V?
YES - Go to step 18.
NO - Go to step 14.

14. Turn the ignition switch OFF.
15. Disconnect PCM connector C (44P).





16. Check for continuity between PCM connector terminal C13 and output shaft (countershaft) speed sensor connector terminal No. 1.
Is there continuity?
YES - Go to step 17.
NO - Repair open in the wire between PCM connector terminal C13 and the output shaft (countershaft) speed sensor, then go to step 32.





17. Check for continuity between PCM connector terminal C13 and body ground.
Is there continuity?
YES - Repair short to ground in the wire between PCM connector terminal C13 and the output shaft (countershaft) speed sensor, then go to step 32.
NO - Check for loose or poor connections at PCM connector terminal C13. If the connection is OK, update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck for DTC P0721. If the symptom/indication goes away with a known-good PCM, replace the original PCM, then go to step 32.

18. Turn the ignition switch OFF.
19. Disconnect PCM connector C (44P).





20. Check for continuity between output shaft (countershaft) speed sensor connector terminal No. 2 and body ground.
Is there continuity?
YES - Repair short to ground in the wire between PCM connector terminal C43 and output shaft (countershaft) speed sensor connector, then go to step 32.
NO - Go to step 2 1.





21. Check for continuity between PCM connector terminal C14 and output shaft (countershaft) speed sensor connector terminal No. 3.
Is there continuity?
YES - Go to step 22.
NO - Repair open in the wire between output shaft (countershaft) speed sensor connector and PCM connector terminal C14, then go to step 32.

22. Connect PCM connector C (44P).
23. Turn the ignition switch ON (II).





24. Measure voltage between output shaft (countershaft) speed sensor connector terminals No. 2 and No. 3.
Is there about 5 V?
YES - Go to step 28.
NO - Go to step 25.

25. Turn the ignition switch OFF.
26. Disconnect PCM connector C (44P).





27. Check for continuity between PCM connector terminal C43 and output shaft (countershaft) speed sensor connector terminal No. 2.
Is there continuity?
YES - Update the PCM if it does not have the latest software. or substitute a known-good PCM, then recheck for DTC P0721. If the symptom/indication goes away with a known-good PCM, replace the original PCM, then go to step 32.
NO - Repair open in the wire between PCM connector terminal C43 and the output shaft (countershaft) speed sensor, then go to step 32.

28. Connect the output shaft (countershaft) speed sensor connector.
29. Clear the DTC with the HDS.
30. Start the engine, run the vehicle in the D position with engine speed 2,000 rpm or higher for more than 10 seconds. Slow down and stop the wheels.
31. 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?
YES - Replace the output shaft (countershaft) speed sensor, then go to step 32.
NO - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck for DTC P0721. If the symptom/indication goes away with a known-good PCM, replace the original PCM, then go to step 32.

32. Clear the DTC with the HDS.
33. Start the engine, run the vehicle in the D position with engine speed 2,000 rpm or higher for more than 10 seconds. Slow down and stop the wheels.
34. 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?
YES - Troubleshooting is complete.
NO - If the PCM was updated and the screen indicates FAILED, substitute a known-good PCM, then return to step 32. If the PCM was substituted and the screen indicates FAILED, return to step 1 and recheck. If the screen indicates NOT COMPLETED, return to step 33.