DTC Troubleshooting
DTC Troubleshooting: P0720
DTC P0720:
Output Shaft (Countershaft) Speed Sensor Circuit Malfunction
NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information How to Troubleshoot the Fuel and Emissions Systems.
1. Start the engine. Hold the engine speed at 3,000 rpm without load (in neutral) until the radiator fan comes on, then let it idle.
2. Test-drive for several minutes.
3. Check the C SHAFT SPD in the DATA LIST with the HDS.
Is any vehicle speed indicated?
YES -
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM.
NO -
Go to step 4.
4. Turn the ignition switch to LOCK (0).
5. Disconnect the output shaft (countershaft) speed sensor 3P connector.
6. Turn the ignition switch to ON (II).
7. Measure the voltage between output shaft (countershaft) speed sensor 3P connector terminal No. 1 and body ground.
Is there about 5 V?
YES -
Go to step 8.
NO -
Repair an open in the wire between the ECM (C13) and the output shaft (countershaft) speed sensor, then go to step 18.
8. Measure the voltage between output shaft (countershaft) speed sensor 3P connector terminal No. 2 and body ground.
Is there about 5 V?
YES -
Go to step 9.
NO -
Go to step 10.
9. Measure the voltage between output shaft (countershaft) speed sensor 3P connector terminals No. 1 and No. 3.
Is there about 5 V?
YES -
Go to step 16.
NO -
Repair an open in the wire between the ECM (C14) and the output shaft (countershaft) speed sensor, then go to step 18.
10. Turn the ignition switch to LOCK (0).
11. Jump the SCS line with the HDS.
12. Disconnect ECM connector B (49P).
13. Check for continuity between ECM connector terminal B38 and body ground.
Is there continuity?
YES -
Repair a short in the wire between the ECM (B38) and the output shaft (countershaft) speed sensor, then go to step 18.
NO -
Go to step 14.
14. Connect output shaft (countershaft) speed sensor 3P connector terminal No. 2 to body ground with a jumper wire.
15. Check for continuity between ECM connector terminal B38 and body ground.
Is there continuity?
YES -
Go to step 25.
NO -
Repair an open in the wire between the ECM (B38) and the output shaft (countershaft) speed sensor, then go to step 18.
16. Turn the ignition switch to LOCK (0).
17. Replace the output shaft (countershaft) speed sensor Output Shaft (Countershaft) Speed Sensor Replacement.
18. Reconnect all connectors.
19. Turn the ignition switch to ON (II).
20. Reset the ECM with the HDS.
21. Do the ECM idle learn procedure ECM/PCM Idle Learn Procedure (M/T).
22. Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 176 °F (80 °C)
- Transmission in 5th
- Engine speed between 2,000-3,000 rpm
- Drive for several minutes, then decelerate (with the throttle fully closed) for 5 seconds
23. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0720 indicated?
YES -
Check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM, then go to step 1.
NO -
Go to step 24.
24. Monitor the OBD STATUS for DTC P0720 in the DTCs MENU with the HDS.
Does the HDS indicate PASSED?
YES -
Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 23, go to the indicated DTC's troubleshooting.
NO -
If the HDS indicates FAILED, check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM, then go to step 1. If the HDS indicates NOT COMPLETED, go to step 22.
25. Reconnect all connectors.
26. Update the ECM if it does not have the latest software ECM/PCM Update (M/T), or substitute a known-good ECM.
27. Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 176 °F (80 °C)
- Transmission in 5th
- Engine speed between 2,000-3,000 rpm
- Drive for several minutes, then decelerate (with the throttle fully closed) for 5 seconds
28. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0720 indicated?
YES -
Check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM. If the ECM was updated, substitute a known-good ECM, then go to step 27. If the ECM was substituted, go to step 1.
NO -
Go to step 29.
29. Monitor the OBD STATUS for DTC P0720 in the DTCs MENU with the HDS.
Does the HDS indicate PASSED?
YES -
If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM Service and Repair. If any other Pending or Confirmed DTCs were indicated in step 28, go to the indicated DTC's troubleshooting.
NO -
If the HDS indicates FAILED, check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM. If the ECM was updated, substitute a known-good ECM, then go to step 27. If the ECM was substituted, go to step 1. If the HDS indicates NOT COMPLETED, go to step 27.