1. Check for continuity between ECM connector terminal A18 and body ground.

Is there continuity?

YES | - | Repair short in the wire between the ECM (A18) and the output shaft (countershaft) speed sensor, then go to Step 17 .
NO | - | Go to Step 24 .

1. Turn the ignition switch OFF.

1. Replace the output shaft (countershaft) speed sensor, then go to Step 16 .

1. Reconnect all connectors.

1. Turn the ignition switch ON (II).

1. Reset the ECM with the HDS.

1. Do the ECM idle learn procedure.

1. Test-drive under the these conditions:
   - Engine coolant temperature above 70 °C (158 °F)
   - Transmission in 5th gear
   - Engine speed at 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 in the DTCs MENU with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES | - | If DTC P0720 is indicated, check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM, then go to Step 1 . If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
NO | - | Go to Step 23 .

1. Monitor the OBD STATUS for DTC P0720 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?

YES | - | Troubleshooting is complete.■
NO | - | If the screen indicates FAILED, go to Step 1 and recheck. If the screen indicates NOT COMPLETED, go to Step 21 and recheck.

1. Update the ECM if it does not have the latest software, or substitute a known-good ECM.

1. Test-drive under the these conditions:
   - Engine coolant temperature above 70 °C (158 °F)
   - Transmission in 5th gear
   - Engine speed at 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 in the DTCs MENU with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES | - | If DTC P0720 is indicated, check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM, then go to Step 1 . If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
NO | - | If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM. ■