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, review the general troubleshooting information - Refer to: How to Troubleshoot the Fuel and Emissions SystemsHow to Troubleshoot the CVT System(CVT System) .
• If DTC P2648 and/or P2649 are stored at the same time as DTC P2646, troubleshoot those DTCs first, then recheck for DTC P2646.

DTC (PGM-FI)

• 1. 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 .

• 2. Problem verification:

  - 1. Turn the vehicle to the ON mode.

  - 2. Clear the DTC with the HDS.

  - 3. 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 and the PCM. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot.

  NO 

  The failure is duplicated. Go to step 3.

• 3. Determine possible failure area (VTM line, others):

  - 1. Turn the vehicle to the OFF (LOCK) mode.

  - 2. Disconnect the following connector.

  Rocker arm oil pressure switch 2P connector

  - 3. Turn the vehicle to the ON mode.

  - 4. Check the parameter(s) below with the HDS.

  Signal	Threshold		Current conditions
  	Values	Unit	Values	Unit
  VTEC PRES SW	ON

  Do the current condition(s) match the threshold?

  YES 

  Go to step 5.

  NO 

  Go to step 4.

• 4. VTEC system oil pressure check:

  - 1. Turn the vehicle to the OFF (LOCK) mode.

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

  Courtesy of HONDA, U.S.A., INC.

  - 3. Reconnect the following connector.

  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 about 392 kPa (4.00 kgf/cm² , 56.9 psi)?

  YES 

  Replace the rocker arm oil pressure switch .

  NO 

  Inspect the VTEC system. If it is OK, replace the rocker arm oil control valve .

• 5. Shorted wire check (VTM line):

  - 1. Turn the vehicle to the OFF (LOCK) mode.

  - 2. Jump the SCS line with the HDS, and wait more than 1 minute.

  - 3. Disconnect the following connector.

  PCM connector B (51P)

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

  Test condition	Vehicle OFF (LOCK) mode
  	Rocker arm oil pressure switch 2P connector: disconnected
  	PCM connector B (51P): disconnected
  Test point 1	PCM connector B (51P) No. 21
  Test point 2	Body ground

  Is there continuity?

  YES 

  Repair a short in the VTM wire between the PCM (B21) and the rocker arm oil pressure switch.

  NO 

  The VTM wire is OK. Update the PCM if it does not have the latest software, or substitute a known-good PCM , then recheck. If DTC P2646 goes away and the PCM was updated, troubleshooting is complete. If DTC P2646 goes away and the PCM was substituted, replace the original PCM .