DTC Troubleshooting

Control System DTCs

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 Test Hose 07AAJ-PY4A100
*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 How To Troubleshoot The Fuel And Emissions Systems.
* If DTC P2648 and/or P2649 are stored at the same time as DTC P2646, troubleshoot those DTCs first, then recheck for DTC P2646.

1. Oil level check:

Oil level check
-1. Check the engine oil level.

Is the level OK?
-YES- Go to step 2.
-NO- Adjust the engine oil to the proper level Testing and Inspection, then do the repair verification.

2. Problem verification:

Problem verification
-1. Do the VTEC TEST in the INSPECTION MENU with the HDS.

Does is show OFF in the DATA LIST?
-YES- Go to step 3.
-NO- 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.

3. Determine of possible failure area (VT_SW_IN line, others):

Determine possible failure area (VT_SW_IN line, others)
-1. Turn the ignition switch to LOCK (0).

-2. Disconnect the following connector.





-3. Turn the ignition switch to ON (II).

-4. Check the VTEC PRES SW in the DATA LIST with the HDS.

Is the result OK?
-YES- Go to step 5.
-NO- Go to step 4.

4. VTEC system oil pressure check:

VTEC system oil pressure check
-1. Turn the ignition switch to LOCK (0).

-2. Remove the rocker arm oil pressure switch (A) from the rocker arm oil control valve, and attach the special tools as shown, then attach the rocker arm oil pressure switch to the oil pressure gauge adapter (B).





-3. Reconnect the rocker arm oil pressure switch 2P connector.

-4. Start the engine.

-5. Do the VTEC TEST in the INSPECTION MENU with the HDS.

-6. Check the oil pressure.

Does the oil pressure increase to at least 392 kPa (4.0 kgf/cm2, 56.9 psi)?
-YES- The VTEC system oil pressure is OK. Replace the rocker arm oil pressure switch Service and Repair, then do the repair verification.
-NO- Inspect the VTEC system. If it is OK, replace the rocker arm oil control valve Rocker Arm Oil Control Valve Removal and Installation, then do the repair verification.

5. Shorted wire check (VT_SW_IN line):

Shorted wire check (VT_SW_IN line)
-1. Turn the ignition switch to LOCK (0).

-2. Jump the SCS line with the HDS.

-3. Disconnect the following connector.





-4. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- Repair a short in the VT_SW_IN wire between the ECM (C13) and the rocker arm oil pressure switch, then do the repair verification.
-NO- The VT_SW_IN wire is OK. Update the ECM ECM/PCM Update if it does not have the latest software, or substitute a known-good ECM Service and Repair, then do the repair verification.

Repair verification:

-1. Reconnect all connectors.

-2. Turn the ignition switch to ON (II).

-3. Reset the ECM with the HDS How To Troubleshoot The Fuel And Emissions Systems.

-4. Do the ECM idle learn procedure ECM/PCM Idle Learn Procedure.

-5. Do the VTEC TEST in the INSPECTION MENU with the HDS.

-6. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P2646 indicated?
-YES- Check for poor connections or loose terminals at the rocker arm oil pressure switch, the rocker arm oil control solenoid, and the ECM. If the ECM was updated, substitute a known-good ECM Service and Repair, then recheck. If the ECM was substituted, go to step 1.
-NO- Troubleshooting is complete. If the ECM was substituted, replace the original ECM Service and Repair. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.