P0721
DTC P0721: Problem in Output Shaft (Countershaft) Speed Sensor CircuitNOTE:
^ Record all freeze data and review 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 HDS.
2. 4WD model: Raise the vehicle, make sure it is securely supported, and allow all four wheels to rotate freely.
2WD model: Raise the front of the vehicle, make sure it is securely supported, and allow the front wheels to rotate freely. Or raise the vehicle.
3. Start the engine, disable the VSA by pressing the VSA OFF switch, 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.
4. Monitor the OBD status for P0721 with the DTC Monitor Tool in DTCs/Freeze Data in A/T Mode Menu for a pass/fail.
Does the result indicate FAILED?
YES - Go to step 5.
NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and PCM. If the tester indicates NOT COMPLETED, return to step 3 and recheck.
5. Turn the ignition switch OFF.
6. Jump the SCS line with the HDS.
7. Disconnect PCM connector A (31P) and output shaft (countershaft) speed sensor connector.
8. Check for continuity between PCM connector terminals A8 and body ground, and between A9 and body ground.
Is there continuity?
YES - Go to step 9.
NO - Repair open in the wire between PCM connector terminals A8, A9, and ground (G101), or repair poor ground (G101), then go to step 28.
9. Connect PCM connector A (31P).
10. Turn the ignition switch ON (II).
11. 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 12.
NO - Go to step 23.
12. Turn the ignition switch OFF.
13. Disconnect PCM connector A (31P).
14. 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 A18 and output shaft (countershaft) speed sensor, then go to step 28.
NO - Go to step 15.
15. Check for continuity between output shaft (countershaft) speed sensor connector terminal No. 3 and PCM connector terminal A24.
Is there continuity?
YES - Go to step 16.
NO - Repair open in the wire between output shaft (countershaft) speed sensor and PCM connector terminal A24, then go to step 30.
16. Connect PCM connector A (31P).
17. Turn the ignition switch ON (II).
18. Measure the voltage between output shaft (countershaft) speed sensor connector terminals No. 2 and No. 3.
Is there about 5 V?
YES - Go to step 19.
NO - Go to step 27.
19. Connect output shaft (countershaft) speed sensor connector.
20. Measure the voltage between PCM connector terminals A18 and A9.
Is there 0 V or about 5 V?
YES - Go to step 21.
NO - Replace the output shaft (countershaft) speed sensor, then go to step 28.
21. Shift to the P position. Start the engine, and let it idle.
22. Shift to the D position, and measure the voltage between PCM connector terminals A18 and A9.
Is there 1.5 - 3.5 V?
YES - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
NO - Replace the output shaft (countershaft) speed sensor, then go to step 28.
23. Measure the voltage between PCM connector terminals A21 and A9.
Is there about 5 V?
YES - Repair open in the wire between PCM connector terminal A21 and the output shaft (countershaft) speed sensor, then go to step 28.
NO - Go to step 24.
24. Turn the ignition switch OFF.
25. Disconnect PCM connector A (31P).
26. Check for continuity between PCM connector terminal A21 and body ground.
Is there continuity?
YES - Repair short to ground in the wire between PCM connector terminal A21 and the output shaft (countershaft) speed sensor connector, then go to step 28.
NO - Check for loose or poor connections at PCM connector terminal A21. If the connection is OK, update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
27. Measure the voltage between PCM connector terminals A18 and A9.
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 28.
NO - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.
28. Clear the DTC with the HDS.
29. Start the engine, disable the VSA by pressing the VSA OFF switch, 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.
30. Monitor the OBD status for P0721 with the DTC Monitor Tool in DTCs/Freeze Data in A/T Mode Menu for a pass/fail.
Does the result indicate PASSED?
YES - Troubleshooting is complete.
NO - Return to step 1 and recheck.