P0721
DTC P0721: Problem in Output Shaft (Countershaft) Speed Sensor CircuitNOTE:
^ Record all freeze data and review the 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. Record all freeze data, and clear the DTC with the HDS.
2. Check for proper output shaft (countershaft) speed sensor installation.
3. Raise the vehicle, make sure it is securely supported, and allow the all four wheels to rotate freely.
4. Start the engine, drive 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. Check the OBD status in DTC Monitor Tool from DTCs/Freeze Data in A/T Mode Menu for a pass/fail test of code P0721.
Did the result indicate a fail?
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. If the tester indicates NOT COMPLETE, return to step 4, and recheck.
6. Turn the ignition switch OFF
7. Jump the SCS line with the HDS.
8. Disconnect PCM connectors B (44P), C (44P), and output shaft (countershaft) speed sensor connector.
9. Check for continuity between PCM connector terminals B1 and body ground, between B36 and body ground, between B43 and body ground, and between C40 and body ground.
Is there continuity?
YES-Go to step 10.
NO-Repair open in the wires between PCM connector terminals B1, B36, B43, C40, and ground (G101), or repair poor ground (G101), then go to step 30.
10. Connect PCM connectors B (44P) and C (44P).
11. Turn the ignition switch ON (II).
12. 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 16.
NO-Go to step 13.
13. Turn the ignition switch OFF.
14. Disconnect PCM connector B (44P).
15. Check for continuity between PCM connector terminal B18 and output shaft (countershaft) speed sensor connector terminal No. 1.
Is there continuity?
YES-Check for loose or poor connections at PCM connector terminal B18. 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.
NO-Repair open in the wire between PCM connector terminal B18 and the output shaft (countershaft) speed sensor, then go to step 30.
16. Turn the ignition switch OFF.
17. Disconnect PCM connector B (44P).
18. Check for continuity between output shaft (countershaft) speed sensor connector terminal No. 2 and body ground.
Wire side of female terminals
Is there continuity?
YES-Repair short to ground in the wire between PCM connector terminal B40 and output shaft (countershaft) speed sensor connector, then go to step 30.
NO-Go to step 19.
19. Check for continuity between PCM connector terminal B33 and the No. 3 terminal of the output shaft (countershaft) speed sensor connector.
Is there continuity?
YES-Go to step 20.
NO-Repair open in the wire between the output shaft (countershaft) speed sensor connector and PCM connector terminal B33, then go to step 30.
20. Connect PCM connector B (44P).
21. Turn the ignition switch ON (II).
22. Measure the voltage between output shaft (countershaft) speed sensor connector terminals No. 2 and No. 3.
Wire side of female terminals
Is thereabout 5 V?
YES-Go to step 26.
NO-Go to step 23.
23. Turn the ignition switch OFF.
24. Disconnect PCM connector B (44P).
25. Check for continuity between PCM connector terminal B40 and output shaft (countershaft) speed sensor connector terminal No. 2.
Wire side of female terminals
Is there continuity?
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 6 known-good PCM, replace the original PCM.
NO-Repair open in the wire between PCM connector terminal B40 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 HDS.
28. Start the engine, drive 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.
29. Check the OBD status in DTC Monitor Tool from DTCs/Freeze Data in A/T Mode Menu for a pass/fail test of code P0721.
Did the result indicate a fail?
YES-Replace the output shaft (countershaft) speed sensor, then go to step 30.
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.
30. Clear the DTC with the HDS.
31. Test-drive the vehicle for several minutes under the same conditions as those indicated by the freeze data.
32. Check the OBD status in DTC Monitor Tool from DTCs/Freeze Data in A/T Mode Menu for a pass/fail test of code P0721.
Did the result indicate a pass?
YES-The problem has been corrected.
NO-Return to step 1 and recheck.