DTC Troubleshooting: P0720 (122)
  1. Check for continuity between ECM connector terminal B38 and body ground.
Is there continuity?
YES -
Go to Step 25 .
NO -
Repair open in the wire between the ECM (B38) and the output shaft (countershaft) speed sensor, then go to Step 18 .
  1. Turn the ignition switch to LOCK (0).
  1. Replace the output shaft (countershaft) speed sensor.
  1. Reconnect all connectors.
  1. Turn the ignition switch to ON (II).
  1. Reset the ECM with the HDS.
  1. Do the ECM idle learn procedure.
  1. Test-drive under these conditions:
    • Engine coolant temperature (ECT SENSOR 1) above 70 °C (158 °F)
    • Transmission in 5th gear
    • Engine speed between 2,000−3,000 rpm (min −1 )
    • Drive for several minutes, then decelerate (with the throttle fully closed) for 8 seconds
  1. Check for Temporary DTCs or 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 .
  1. Monitor the OBD STATUS for DTC P0720 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -
Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in Step 23 , go to the indicated DTC's troubleshooting.■
NO -
If the screen 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 screen indicates NOT COMPLETED, go to Step 22 .
  1. Reconnect all connectors.
  1. Update the ECM if it does not have the latest software, or substitute a known-good ECM.
  1. Test-drive under these conditions:
    • Engine coolant temperature (ECT SENSOR 1) above 70 °C (158 °F)
    • Transmission in 5th gear
    • Engine speed between 2,000−3,000 rpm (min −1 )
    • Drive for several minutes, then decelerate (with the throttle fully closed) for 8 seconds
  1. Check for Temporary DTCs or 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 .
  1. Monitor the OBD STATUS for DTC P0720 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -
If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM. If any other Temporary DTCs or DTCs were indicated in Step 28 , go to the indicated DTC's troubleshooting.■
NO -
If the screen 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 screen indicates NOT COMPLETED, go to Step 27 .