DTC Troubleshooting

DTC P2646: Rocker Arm Oil Pressure Switch (VTEC Oil Pressure Switch) Circuit Low Voltage

Special Tools Required
- Pressure gauge adapter 07NAJ-P07010A
- A/T low pressure gauge w/panel 07406-0070301
- A/T pressure hose 07406-0020201
- A/T pressure hose, 2,210 mm 07MAJ-PY4011A
- A/T pressure adapter 07MAJ-PY40120
- Oil pressure hose 07ZAJ-S5AA200

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.

1. Check the engine oil level.

Is the level OK?

YES - Go to step 2.

NO - Adjust the engine oil to the proper level, then Go to step 19.

2. Turn the ignition switch ON (11).
3. Clear the DTC with the HDS.
4. Do the VTEC TEST in the INSPECTION MENU with the HDS.

Is the result OK?

YES - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the rocker arm oil pressure switch (VTEC oil pressure switch), the rocker arm oil control solenoid (VTEC solenoid valve), and the ECM/PCM.

NO - Go to step 5.

5. Turn the ignition switch OFF.
6. Disconnect the rocker arm oil pressure switch (VTEC oil pressure switch) 2P connector.
7. Turn the ignition switch ON (II).
8. Check the VTEC PRES SW in the DATA LIST with the HDS.

Is SWITCH ON indicated?

YES - Go to step 14.

NO - Go to step 9.

9. Turn the ignition switch OFF.




10. Remove the rocker arm oil pressure switch (VTEC oil pressure switch) (A) and install the special tools as shown, then install the rocker arm oil pressure switch (VTEC oil pressure switch) to the oil pressure gauge adapter (B).

NOTE: Install the parts in the reverse order of removal with a new O-ring.

11. Start the engine.
12. Do the VTEC TEST in the INSPECTION MENU with the HDS.
13. Check the oil pressure.

Does the oil pressure increase to at least 392 kPa (56.9 psi, 4.0 kgf/sq.cm)?

YES - Replace the rocker arm oil pressure switch (VTEC oil pressure switch), then Go to step 18.

NO - Inspect the VTEC system. If it is OK, replace the rocker arm oil control valve (VTEC solenoid valve), then Go to step 18.

14. Turn the ignition switch OFF.
15. Jump the SCS line with the HDS.
16. Disconnect ECM/PCM connector B (24P).




17. Check for continuity between ECM/PCM connector terminal B11 and body ground.

Is there continuity?

YES - Repair short in the wire between the ECM/PCM (B11) and the rocker arm oil pressure switch (VTEC oil pressure switch), then Go to step 18.

NO - Go to step 25.

18. Reconnect all connectors.
19. Turn the ignition switch ON (II).
20. Reset the ECM/PCM with the HDS.
21. Do the ECM/PCM idle learn procedure.
22. Do the VTEC TEST in the INSPECTION MENU with the HDS.
23. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P2646 indicated?

YES - Check for poor connections or loose terminals at the rocker arm oil pressure switch (VTEC oil pressure switch), the rocker arm oil control solenoid (VTEC solenoid valve), and the ECM/PCM, then Go to step 1.

NO - Go to step 24.

24. Monitor the 08D STATUS for DTC P2646 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 rocker arm oil pressure switch (VTEC oil pressure switch), the, rocker arm oil control solenoid (VTEC solenoid valve) and the ECM/PCM, then Go to step 1. If the screen indicates NOT COMPLETED, Go to step. 22.

25. Reconnect all connectors.
26. Update the ECM/PCM if it does not have the latest software, or substitute a known good ECM/PCM.
27. Do the VTEC TEST in the INSPECTION MENU with the HDS.
28. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P2646 indicated?

YES - Check for poor connections or loose terminals at the rocker arm oil pressure switch (VTEC oil pressure switch), the rocker arm oil control solenoid (VTEC solenoid valve), and the ECM/PCM. If the ECM/PCM was updated, substitute a known good ECM/PCM, then Go to step 27. If the ECM/PCM was substituted, Go to step 1.

NO - Go to step 9.

29. Monitor the OBD STATUS for DTC P2646 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?

YES - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM. If any other Temporary DTCs or DTC's were indicated in step 28, Go to indicated DTC's troubleshooting.

NO - If the screen indicates FAILED,check for poor connections or loose terminals at the rocker arm oil pressure switch (VTEC oil pressure switch), the rocker arm oil control solenoid (VTEC solenoid valve), and the ECM/PCM. If the ECM/PCM was updated, substitute a known good ECM/PCM, then Go to step 27. If the ECM/PCM was substituted, Go to step 1. If the screen indicates NOT COMPLETED, Go to step :27.