P0720
DTC P0720: Countershaft Speed Sensor Circuit Malfunction1. Test-drive the vehicle above 13 mph (20 km/h) for several minutes.
2. Check the C SHAFT SPD in the DATA LIST with the Honda PGM Tester or 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 countershaft speed sensor and the ECM.
NO - Go to step 3.
3. Turn the ignition switch OFF.
4. Disconnect the countershaft speed sensor 3P connector.
5. Turn the ignition switch ON (II).
6. Measure voltage between countershaft speed sensor 3P connector terminal No.1 and body ground.
Is there about 5 V?
YES - Go to step 7.
NO - Repair open in the wire between the ECM (A21) and the countershaft speed sensor, then go to step 17.
7. Measure voltage between countershaft speed sensor 3P connector terminal No.2 and body ground.
Is there about 5 V?
YES - Go to step 8.
NO - Go to step 9.
8. Measure voltage between countershaft speed sensor 3P connector terminal No.1 and No.3.
Is there about 5 V?
YES - Go to step 14.
NO - Repair open in the wire between the countershaft speed sensor and G101, then go to step 17.
9. 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 countershaft speed sensor, then go to step 17.
NO - Go to step 10.
10. Turn the ignition switch OFF.
11. Jump the SCS line with the Honda PGM Tester or the HDS.
12. Disconnect ECM connector A (31P).
13. Check for continuity between ECM connector terminal A 18 and body ground.
Is there continuity?
YES - Repair short in the wire between the ECM (A18) and the countershaft speed sensor, then go to step 16.
NO - Go to step 22.
14. Turn the ignition switch OFF.
15. Replace the countershaft speed sensor, then go to step 16.
16. Turn the ignition switch ON (II).
17. Do the ECM RESET in the CLEAR MENU with the Honda PGM Tester or the HDS.
18. Do the ECM idle learn procedure.
19. Test-drive the vehicle above 13 mph (20 km/h) for several minutes.
20. Check for Temporary DTCs or DTCs in the DTCs MENU with the Honda PGM Tester or the HDS.
Are any Temporary DTCs or DTCs indicated?
YES - If DTC P0720 is indicated, check for poor connections or loose terminals at the 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 troubleshooting.
NO - Go to step 21.
21. Monitor the OBD STATUS for DTC P0720 in the DTCs MENU with the Honda PGM Tester or 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 19 and recheck.
22. Update the ECM if it does not have the latest software, or substitute a known-good ECM.
23. Test-drive the vehicle above 13 mph (20 km/h) for several minutes.
24. Check for Temporary DTCs or DTCs in the DTCs MENU with the Honda PGM Tester or the HDS.
Are any Temporary DTCs or DTCs indicated?
YES - If DTC P0720 is indicated, check for poor connections or loose terminals at the 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 troubleshooting.
NO - If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM.