P1259

DTC P1259: A problem in the VTEC Oil Pressure Switch circuit or VTEC Solenoid Valve circuit.

Special Tools Required
- Pressure Gauge Adaptor 07NAJ-P07010A
- A/T Low Pressure Gauge W/Panel 07406-0070300
- A/T Pressure Hose, 2,210 mm 07MAJ-PY4011A
- A/T Pressure Adaptor 07MAJ-PY40120

1. Do the Powertrain Control Module (PCM) reset procedure.
2. Start the engine.
3. Warm up the engine to normal operating temperature (cooling fan comes on).
4. Road Test the vehicle: Accelerate in 1st gear to an engine speed over 4,000 rpm. Hold that engine speed for at least 2 seconds. If DTC P1259 is not repeated during the first road test, repeat this test two more times.
Is DTC P1259 indicated ?
YES-Go to step 5.
NO-Intermittent failure, system is OK at this time. Check for poor connections or loose wires at the VTEC solenoid valve and PCM.
5. Turn the ignition switch OFF.
6. Disconnect the VTEC oil pressure switch 2P connector.





7. Check for continuity on the VTEC oil pressure switch between the pressure switch 2P connector terminals No.1 and No. 2.
Is there continuity?
YES-Go to step 8.
NO-Replace the VTEC oil pressure switch.
8. Turn the ignition switch ON (II).





9. Measure the voltage between VTEC oil pressure switch harness 2P connector No. 1 terminal and body ground.
Is there battery voltage?
YES-Go to step 10.
NO-Inspect for an open or short to ground in the wire between the VTEC oil pressure switch and the PCM (C10). If the wire is OK, substitute a known good PCM and recheck.





10. Measure voltage across the VTEC oil pressure switch harness 2P connector.
Is there battery voltage?
YES-Go to step 11.
NO-Repair open in the wire between the VTEC oil pressure switch and G101. If the wire is OK, substitute a known-good PCM and rechecked
11. Turn the ignition switch OFF.
12. Disconnect the VTEC solenoid valve 1P connector.





13. Check for continuity on the VTEC solenoid valve between the solenoid valve 1P connector terminal and body ground.
Is there 14 - 30 ohms ?
YES-Go to step 14.
NO-Replace the VTEC solenoid valve.
14. Remove the VTEC oil pressure switch (A) and install the special tools as shown, then reinstall the VTEC oil pressure switch.





15. Reconnect the VTEC solenoid valve 1P connector and VTEC oil pressure switch 2P connector.
16. Connect a tachometer.
17. Warm up the engine to normal operating temperature (cooling fan comes on).
18. Check oil pressure at engine speeds of 1,000, 2,000 and 3,000 rpm. Keep measuring time as short as possible because the engine is running with no load (less than 1 minute).
Is pressure below 49 kPa (0.5 kgf/cm2, 7 psi)?
YES-Go to step 19.
NO-Inspect the VTEC solenoid valve.
19. Turn the ignition switch OFF.
20. Disconnect the VTEC solenoid valve 1P connector.
21. Attach the battery positive terminal to the VTEC solenoid valve terminal.
22. Start the engine and check oil pressure at an engine speed of 3,000 rpm.
Is pressure above 390 kPa (4.0 kgf/cm2, 57 psi)?
YES-Go to step 23.
NO-Inspect the VTEC solenoid valve.





23. With the battery positive terminal still connected to the VTEC solenoid valve, measure voltage between C10 and body ground.
Is there battery voltage above 4,000 rpm?
YES-Go to step 24.
NO-Replace the VTEC oil pressure switch.
24. Turn the ignition switch OFF.
25. Disconnect the battery positive terminal from the VTEC solenoid valve terminal.





26. Check for continuity between the VTEC solenoid valve harness 1P connector terminal and the PCM connector terminal B12.
Is there continuity?
YES-Go to step 27.
NO-Repair open in the wire between the PCM (B12) and VTEC solenoid valve connector.





27. Check for continuity between the VTEC solenoid valve 1P connector terminal and body ground.
Is there continuity?
YES-Repair short in the wire between the PCM (B12) and VTEC solenoid valve connectors
NO-Substitute a known-good PCM and recheck. If symptom indication goes away, replace the original PCM.