DTC Troubleshooting

DTC Troubleshooting: P2646

DTC P2646: Rocker Arm 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. Initial Inspection and Diagnostic Overview

1. Check the engine oil level.

Is the engine oil 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 to ON (II).

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, the rocker arm oil control solenoid, and the ECM.

NO - Go to step 5.


5. Turn the ignition switch to LOCK (0).

6. Disconnect the rocker arm oil pressure switch 2P connector.

7. Turn the ignition switch to 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 to LOCK (0).

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

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 (4.0 kgf/cm2, 56.9 psi)?
YES - Replace the rocker arm oil pressure switch, Rocker Arm Oil Pressure Switch Removal/Installation (M/T) then go to step 18.

NO - Inspect the VTEC system. If it is OK, replace the rocker arm oil control solenoid, Rocker Arm Oil Control Solenoid Replacement (M/T) then go to step 18.






14. Turn the ignition switch to LOCK (0).

15. Jump the SCS line with the HDS.

16. Disconnect ECM connector B (49P).

17. Check for continuity between ECM connector terminal B20 and body ground.

Is there continuity?
YES - Repair short in the wire between the ECM (B20) and the rocker arm oil pressure switch, then go to step 18.

NO - Go to step 24.






18. Reconnect all connectors.

19. Turn the ignition switch to ON (II).

20. Reset the ECM with the HDS.

21. Do the ECM idle learn procedure. 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 and the ECM, then go to step 1.

NO - Troubleshooting is complete. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.


24. Reconnect all connectors.

25. Update the ECM if it does not have the latest software, ECM/PCM Update or substitute a known-good ECM. Initial Inspection and Diagnostic Overview

26. Do the VTEC TEST in the INSPECTION MENU with the HDS.

27. 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 and the ECM. If the ECM was updated, substitute a known-good ECM, Initial Inspection and Diagnostic Overview then go to step 26. If the ECM was substituted, go to step 1.

NO - If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM. Service and Repair If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.