DTC Troubleshooting: P2646
DTC P2646: Rocker Arm Oil Pressure Switch A (Bank 1) 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.
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 Description
Confirmed DTC
Pending DTC
Freeze Frame
P2646 Rocker Arm Oil Pressure Switch A (Bank 1) Circuit Low Voltage
      

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, then do the repair verification.
2.
Problem verification:

Problem verification
?1.
Press the engine start/stop button to select the ON mode.

?2.
Clear the DTC with the HDS.


?3.
Select the VTEC+VCM TEST in the INSPECTION MENU with the HDS, then select the VEB VTEC TEST with the HDS.

  

Does the HDS indicate Normal?

     
YES
     
     
     
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at rocker arm oil pressure switch A (Bank 1) and the PCM.?
     
NO
     
     
     
The failure is duplicated. Go to step 3.
3.
Determine possible failure area (VTMB1 line, Others):

Determine possible failure area (VTMB1 line, Others)
?1.
Press the engine start/stop button to select the OFF mode.

?2.
Disconnect the following connector.

?3.
Press the engine start/stop button to select the ON mode.

?4.
Check the parameter(s) below with the HDS.
Signal
Current conditions
Values
Unit
VTEC PRES SW B1
    

Is ON indicated?

     
YES
     
     
     
Go to step 5.
     
NO
     
     
     
Go to step 4.
4.
VTEC system oil pressure check:

VTEC system oil pressure check
?1.
Press the engine start/stop button to select the OFF mode.

?2.
Remove rocker arm oil pressure switch A (Bank 1), and attach the special tools as shown, then attach rocker arm oil pressure switch A (Bank 1) to the oil pressure gauge adapter (B).


?3.
Reconnect rocker arm oil pressure switch A (Bank 1) 2P connector.

?4.
Start the engine.

?5.
Select the VTEC+VCM TEST in the INSPECTION MENU with the HDS, then select the VEB VTEC TEST with the HDS.

  

?6.
Check the oil pressure.

Does the oil pressure increase to 392 kPa (4.0 kgf/cm2, 56.9 psi)?

     
YES
     
     
     
Replace rocker arm oil pressure switch A (Bank 1), then do the repair verification.
     
NO
     
     
     
5.
Shorted wire check (VTMB1 line):

Shorted wire check (VTMB1 line)
?1.
Press the engine start/stop button to select the OFF mode.

?2.
Jump the SCS line with the HDS.


?3.
Disconnect the following connector.

?4.
Check for continuity between test points 1 and 2.
Test condition
OFF mode
 
Rocker arm oil pressure switch A (Bank 1) 2P connector: disconnected
 
PCM connector C (51P): disconnected
Test circuit
VTMB1
Test point 1
PCM connector C (51P) No. 22 (PUR)
Test point 2
Body ground


Is there continuity?

     
YES
     
     
     
Repair a short in the VTMB1 wire between rocker arm oil pressure switch A (Bank 1) and the PCM (C22), then do the repair verification.
     
NO
     
     
     
The VTMB1 wire is OK. Update the PCM if it does not have the latest software, or substitute a known-good PCM, then do the repair verification.
Repair verification:

?1.
Reconnect all connectors.

?2.
Exit the SCS mode with the HDS.


?3.
Press the engine start/stop button to select the ON mode.

?4.
Reset the PCM with the HDS.


?5.
Do the PCM idle learn procedure.

?6.
Select the VTEC+VCM TEST in the INSPECTION MENU with the HDS, then select the VEB VTEC TEST with the HDS.

  

?7.
Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P2646 Rocker Arm Oil Pressure Switch A (Bank 1) Circuit Low Voltage
      


Is DTC P2646 indicated?

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