P2646

DTC P2646: VTEC Oil Pressure Switch Circuit Low Voltage

Special Tools Required
- Pressure gauge adaptor 07NAJ-P07010A
- A/T low pressure gauge w/panel 07406-0070300
- A/T pressure hose 07406-0020201
- A/T pressure hose, 2,210 mm 07MAJ-PY4011A
- A/T pressure adaptor 07MAJ-PY40120
- Oil pressure hose 07ZAJ-S5A0200

1. Turn the ignition switch OFF.
2. Check the engine oil level.

Is the level OK?

YES - Go to step 3.

NO - Adjust the engine oil to the proper level.

3. Turn the ignition switch ON (II).
4. Reset the ECM/PCM.
5. Start the engine. Hold the engine speed at 3,000 rpm with no load (in Park or neutral) until the radiator fan comes on, then let it idle.
6. Test-drive under these conditions:
Accelerate in 1st gear to an engine speed over 5,000 rpm. Hold the speed for at least 2 seconds.

Is DTC P2646 indicated?

YES - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the VTEC oil pressure switch, at the VTEC solenoid valve and at the ECM/PCM.

NO - Go to step 7.

7. Turn the ignition switch OFF.
8. Remove the resonator.




9. Remove the VTEC oil pressure switch (A), and install the special tools as shown, then install the VTEC oil pressure switch (A) on the oil pressure gauge adapter.

NOTE: Install the part in the reverse order of removal with a new O-ring.

10. Disconnect the VTEC solenoid valve 1P connector.
11. Start the engine. Hold the engine speed at 3,000 rpm with no load (in Park or neutral) until the radiator fan comes on, then let it idle.
12. Attach the battery positive terminal to VTEC solenoid valve 1P connector terminal No. 1.
13. Start the engine and check the oil pressure at an engine speed of 3,000 rpm.

Is the oil pressure above 390 kPa (4.0 kgf/Sq.cm, 57 psi)?

YES - Go to step 14.

NO - Inspect the VTEC solenoid valve.

14. Disconnect the VTEC oil pressure switch 2P connector.




15. At the VTEC oil pressure switch side, check for continuity between VTEC oil pressure switch terminals No. 1 and No. 2 with the engine at 3,000 rpm.

Is there continuity?

YES - Replace the VTEC oil pressure switch.

NO - Go to step 16.

16. Turn the ignition switch OFF.
17. Disconnect the battery terminals from the VTEC solenoid valve terminal connector.
18. Disconnect ECM/PCM connector B (24P).




19. Check for continuity between ECM/PCM connector terminal B9 and body ground.

Is there continuity?

YES - Repair short in the wire between the ECM/PCM (B9) and the VTEC oil pressure switch.

NO - Go to step 20.




20. Check for continuity between ECM/PCM connector terminal B15 and body ground.

Is there continuity?

YES - Repair open in the wire between the ECM/PCM (B15) and the VTEC solenoid valve.

NO - Go to step 21.




21. Connect the VTEC solenoid valve 1P connector terminal No. 1 and body ground with a jumper wire.




22. Check for continuity between ECM/PCM connector terminal B15 and body ground.

Is there continuity?

YES - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM,then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.

NO - Repair open in the wire between the ECM/PCM (B15) and the VTEC solenoid valve.