DTC Troubleshooting: P0720 (122)

DTC P0720: Output Shaft (Countershaft) Speed Sensor Circuit Malfunction NOTE: This DTC only occurs on M/T vehicles. Start the engine. Hold the engine speed at 3,000 rpm (min −1 ) without load (in neutral) until the radiator fan comes on, then let it idle. Test-drive several minutes. Check the C SHAFT SPD in the DATA LIST with the HDS. Is any vehicle speed indicated?
YES | - | Intermittent failure, 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 .
Turn the ignition switch OFF. Disconnect the output shaft (countershaft) speed sensor 3P connector. Turn the ignition switch ON (II). Measure 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 open in the wire between the ECM (A21) and the output shaft (countershaft) speed sensor, then go to Step 17 .

Measure 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 .

Measure voltage between output shaft (countershaft) speed sensor 3P connector terminals No. 1 and No. 3. Is there about 5 V?
YES | - | Go to Step 15 .
NO | - | Repair open in the wire between the output shaft (countershaft) speed sensor and G101, then go to Step 17 .

Measure voltage between ECM connector terminal A18 and body ground. Is there about 5 V?
YES | - | Repair open in the wire between the ECM (A18) and the output shaft (countershaft) speed sensor, then go to Step 17 .
NO | - | Go to Step 11 .
Turn the ignition switch OFF. Jump the SCS line with the HDS. Disconnect ECM connector A (31P). |

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 .
Turn the ignition switch OFF. Replace the output shaft (countershaft) speed sensor, then go to Step 16 . Reconnect all connectors. Turn the ignition switch ON (II). Reset the ECM with the HDS. Do the ECM idle learn procedure. 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 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 .
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.
Update the ECM if it does not have the latest software, or substitute a known-good ECM. 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 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. ■