Fig. 407: DTC Troubleshooting Flow Chart (P2646)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Special Tools Required
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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:
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Before you troubleshoot, record all freeze data and any on-board
snapshot, and review the general troubleshooting information See HOW
TO TROUBLESHOOT THE A/T SYSTEM or HOW TO TROUBLESHOOT THE
FUEL AND EMISSIONS SYSTEMS .
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If DTC P2648 and/or P2649 are stored at the same time as DTC P2646,
troubleshoot those DTCs first, then recheck for DTC P2646.
Confirmed
DTC
Pending
DTC
Freeze
Frame
DTC Description
P2646 ROCKER ARM OIL PRESSURE SWITCH CIRCUIT
LOW VOLTAGE
1. Oil level check:
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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 do the repair verification .
2. Problem verification:
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1. 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 PCM.
NO : The failure is duplicated. Go to step 3.
3. Determine possible failure area (VT SW line, others):
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1. Turn the ignition switch to LOCK (0).
2. Disconnect the following connector.
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Rocker arm oil pressure switch 2P connector
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3. Turn the ignition switch to ON (II).
4. Check the parameter(s) below with the HDS.
Malfunction threshold Current conditions
Values Unit Values Unit
Signal
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:
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1. Turn the ignition switch to LOCK (0).
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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).
Fig. 408: Checking VTEC System Oil Pressure Using Tools
Courtesy of AMERICAN HONDA MOTOR CO., INC.
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3. Reconnect the rocker arm oil pressure switch 2P connector.
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4. Start the engine.
5. Do the VTEC TEST in the INSPECTION MENU with the HDS.
6. Check the oil pressure.
2
Does the oil pressure increase to at least 392 kPa (4.0 kgf/cm , 56.9 psi)?
YES : The VTEC system oil pressure is OK. REPLACE THE ROCKER ARM OIL PRESSURE
SWITCH , then do the repair verification .
NO : Inspect the VTEC system. If it is OK, REPLACE THE ROCKER ARM OIL CONTROL VALVE ,
then do the repair verification .
5. Shorted wire check (VT SW line):
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1. Turn the ignition switch to LOCK (0).
2. Jump the SCS line with the HDS.
3. Disconnect the following connector.
PCM connector C (49P)
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4. Check for continuity between test points 1 and 2.
Test condition IG LOCK (0)
PCM connector C (49P): disconnected
Test circuit VT SW
Test point 1 PCM connector C (49P) No. 13 (LT BLU)
Test point 2 Body ground
Fig. 409: Checking Continuity Between PCM Connector C (49P) No. 13 (LT BLU) And Body
Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES : Repair a short in the VT SW wire between the PCM (C13) and the rocker arm oil pressure switch,
then do the repair verification .
NO : The VT SW wire is OK. Update the PCM See PCM UPDATE or PCM REMOVAL AND
INSTALLATION if it does not have the latest software, or substitute a known-good PCM See PCM
REMOVAL AND INSTALLATION or PCM UPDATE , then do the repair verification .
REPAIR VERIFICATION
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1. Reconnect all connectors.
2. Turn the ignition switch to ON (II).
3. Reset the PCM with the HDS See HOW TO TROUBLESHOOT THE A/T SYSTEM or HOW
TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS .
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4. DO THE 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.
Confirmed
DTC
Pending
DTC
Freeze
Frame
DTC Description
P2646 ROCKER ARM OIL PRESSURE SWITCH CIRCUIT
LOW VOLTAGE
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 PCM. If the PCM was updated, substitute a known-good PCM See PCM
REMOVAL AND INSTALLATION or PCM UPDATE , then recheck. If the PCM was substituted, go to
step 1.
NO : Troubleshooting is complete. If the PCM was substituted, replace the original PCM See PCM
REMOVAL AND INSTALLATION or PCM UPDATE . If any other Pending or Confirmed DTCs are
indicated, go to the indicated DTC's troubleshooting.
DTC P2647: ROCKER ARM OIL PRESSURE SWITCH CIRCUIT HIGH
VOLTAGE
Fig. 410: DTC Troubleshooting Flow Chart (P2647)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
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