DTC Troubleshooting

DTC Troubleshooting: P0721 (9), P0722 (9)

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

DTC P0722: Problem in Output Shaft (Countershaft) Speed Sensor Circuit (No Signal Input)

NOTE:

- Before you troubleshoot, record all freeze data and any on-board snapshot with the HDS, and review General Troubleshooting Information. How to Troubleshoot A/T Systems

- This code is caused by an electrical circuit problem and cannot be caused by a mechanical problem in the transmission.

1. Check for proper output shaft (countershaft) speed sensor installation. Output Shaft (Countershaft) Speed Sensor Replacement (A/T) If the sensor is installed improperly, correct the problem, then go to step 27.

2. Turn the ignition switch to ON (II).

3. Clear the DTC with the HDS.

4. Block the rear wheels and 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, and turn the VSA off (the light on the VSA OFF switch comes on). Run the vehicle in either 2nd, 3rd, 4th, or 5th gear (not 1st) in D with the engine speed at 2,000 rpm or higher, for at least 10 seconds. Slow down and stop the wheels.

6. Monitor the OBD status for P0721 or P0722 in the DTCs MENU with the HDS.

Does the HDS indicate FAILED?
YES - Go to step 7.

NO - If the HDS indicates PASSED, intermittent failure, the system is OK at this time. Check for loose or poor connections between the PCM and output shaft (countershaft) speed sensor connectors. If the HDS 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 connectors B (49P) and C (49P).

10. Check for continuity between PCM connector terminals B41 and body ground, and between C41 and body ground.

Is there continuity?
YES - Go to step 11.

NO - Repair open in the wires between PCM connector terminals B41, C41 and body ground (G101), or repair poor body ground (G101), then go to step 26.






11. Connect PCM connectors B (49P) and C (49P).

12. Disconnect the output shaft (countershaft) speed sensor connector.

13. Turn the ignition switch to ON (II).

14. Measure the voltage between output shaft (countershaft) speed sensor connector terminal No. 1 and body ground.

Is there about 5 V?
YES - Go to step 19.

NO - Go to step 15.






15. Turn the ignition switch to LOCK (0).

16. Jump the SCS line with the HDS.

17. Disconnect PCM connector B (49P).

18. Check for continuity between PCM connector terminal B36 and output shaft (countershaft) speed sensor connector terminal No. 1.

Is there continuity?
YES - Go to step 25.

NO - Repair open in the wire between PCM connector terminal B36 and the output shaft (countershaft) speed sensor, then go to step 26.






19. Measure the voltage between output shaft (countershaft) speed sensor connector terminals No. 2 and No. 3.

Is there about 5 V?
YES - Replace the output shaft (countershaft) speed sensor, Output Shaft (Countershaft) Speed Sensor Replacement (A/T) then go to step 26.

NO - Go to step 20.






20. Turn the ignition switch to LOCK (0).

21. Jump the SCS line with the HDS.

22. Disconnect PCM connector B (49P).

23. Check for continuity between output shaft (countershaft) speed sensor connector terminal No. 2 and body ground.

Is there continuity?
YES - Repair short to body ground in the wire between PCM connector terminal B38 and the output shaft (countershaft) speed sensor, then go to step 26.

NO - Go to step 24.






24. Check for continuity between PCM connector terminal B34 and output shaft (countershaft) speed sensor connector terminal No. 3.

Is there continuity?
YES - Go to step 25.

NO - Repair open in the wire between output shaft (countershaft) speed sensor connector and PCM connector terminal B34, then go to step 26.






25. Check for continuity between PCM connector terminal B38 and output shaft (countershaft) speed sensor connector terminal No. 2.

Is there continuity?
YES - Go to step 32.

NO - Repair open in the wire between PCM connector terminal B36 and the output shaft (countershaft) speed sensor, then go to step 26.






26. Reconnect all connectors.

27. Turn the ignition switch to ON (II).

28. Clear the DTC with the HDS.

29. Start the engine. Run the vehicle in either 2nd, 3rd, 4th, or 5th gear (not 1st) in D at speeds over 12 mph (20 km/h) for at least 10 seconds. Slow down and stop the wheels.

30. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0721 or P0722 indicated?
YES - Check for poor connections and loose terminals at the output shaft (countershaft) speed sensor and the PCM, then go to step 1.

NO - Go to step 31.


31. Monitor the OBD status for P0721 or P0722 in the DTCs MENU with the HDS.

Does the HDS indicate PASSED?
YES - Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 30, go to the indicated DTC's troubleshooting.

NO - If the HDS 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 HDS indicates NOT COMPLETED, go to step 29.


32. Reconnect all connectors.

33. Update the PCM if it does not have the latest software, ECM/PCM Update or substitute a known-good PCM. How to Troubleshoot A/T Systems

34. Start the engine. Run the vehicle in either 2nd, 3rd, 4th, or 5th gear (not 1st) in D at speeds over 12 mph (20 km/h) for at least 10 seconds. Slow down and stop the wheels.

35. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0721 or P0722 indicated?
YES - Check for poor connections or loose terminals the output shaft (countershaft) speed sensor and the PCM. If the PCM was updated, substitute a known-good PCM, How to Troubleshoot A/T Systems then go to step 34. If the PCM was substituted, 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 HDS indicate PASSED?
YES - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM. Service and Repair If any other Temporary DTCs or DTCs were indicated in step 35, go to the indicated DTC's troubleshooting.

NO - If the HDS 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, How to Troubleshoot A/T Systems then go to step 34. If the PCM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, go to step 34.