DTC P2646: VTEC OIL PRESSURE SWITCH CIRCUIT LOW VOLTAGE
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
5. Start the engine. Hold the engine speed at 3,000 RPM with no load (in neutral) until the radiator fan comes on, then let it idle.
6. Test-drive under following conditions: Accelerate in 1st gear to an engine over 5,000 RPM. Hold the speed for at least 2 seconds.
Is DTC P2646 indicated?
YES: Go to step 7.
NO: Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the VTEC oil pressure switch, the VTEC solenoid valve and the ECM.
7. Turn the ignition switch OFF.
8. Remove the VTEC oil pressure switch (A) and install the special tools as shown, then install the VTEC oil pressure switch (A) to the oil pressure gauge adapter (B).
9. Disconnect the VTEC solenoid valve 2P connector.
10. Start the engine. Hold the engine speed at 3,000 RPM with no load (in neutral) until the radiator fan comes on, then let it idle.
11. Attach the battery positive terminal to VTEC solenoid valve 2P connector terminal No. 2.
12. Start the engine, then connect the battery negative terminal to VTEC solenoid valve 2P connector terminal No. 1, and check the oil pressure at an engine speed of 3,000 RPM.
Is the oil pressure above 390 kPa (4.0 kgf/cm 2 , 57 psi)?
YES: Go to step 13.
NO: Inspect the VTEC solenoid valve
13. Disconnect the VTEC oil pressure switch 2P connector.
14. At VTEC oil pressure switch side, check for continuity between VTEC oil pressure switch terminals No. 1 and No. 2 in the condition of step 12.
Is there continuity?
YES: Replace the VTEC oil pressure switch.
NO: Go to step 15.
15. Turn the ignition switch OFF.
16. Disconnect the battery terminals from the VTEC solenoid valve terminal connector.
17. Disconnect ECM/PCM connector B (24P).
18. Check for continuity between ECM connector terminal B9 and body ground.
Is there continuity?
YES: Repair short in the wire between the ECM (B9) and the VTEC oil pressure switch.
NO: Go to step 19.
19. Check for continuity between VTEC solenoid valve 2P connector terminal No. 1 and body ground.
Is there continuity?
YES: Go to step 20.
NO: Repair open in the wire between the VTEC solenoid valve and G101.
20. Check for continuity between ECM connector terminal B15 and body ground.
Is there continuity?
YES: Repair short in the wire between the ECM (B15) and the VTEC solenoid valve.
NO: Go to step 21.
21. Connect the VTEC solenoid valve 2P connector terminal No. 2 and body ground with a jumper wire.
22. Check for continuity between ECM connector terminal B15 and body ground.
Is there continuity?
YES: Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.
NO: Repair open in the wire between the ECM (B15) and the VTEC solenoid valve
