DTC P1259: VTEC System Malfunction

Special Tools Required

Pressure gauge adapter 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
Hose oil pressure 07ZAJ-S5A0200

Reset the ECM/PCM (see HOW TO RESET THE ECM/PCM ).
Check the engine oil level, and refill if necessary.
Start the engine. Hold the engine at 3.000 RPM with no load (in Park or neutral) unit the radiator fan comes on.
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 2 more times.

Is DTC P1259 indicated?
1. YES - Go to step 5.
2. NO - Intermittent failure, system is OK at this time. Check for poor connections or loose wires at the VTEC solenoid valve and at the ECM/PCM.
Turn the ignition switch OFF.
Remove the resonator (see RESONATOR REPLACEMENT ).
Disconnect the VTEC oil pressure switch 2P connector.
Check for continuity on the VTEC oil pressure switch between the VTEC oil pressure switch 2P connector terminals No. 1 and No. 2.

Fig 1: Checking Continuity On VTEC Oil Pressure Switch Between VTEC Oil Pressure Switch 2-Pin Connector Terminals No. 1 & No. 2

Terminal side of male terminals

Is there continuity?
1. YES - Go to step 9.
2. NO - Replace the VTEC oil pressure switch.
Turn the ignition switch ON (II).
Measure voltage between the VTEC oil pressure switch 2P connector terminal No. 1 and body ground.

Fig 2: Measuring Voltage Between VTEC Oil Pressure Switch 2-Pin Connector Terminal No. 1 & Body Ground

Is there battery voltage?
1. YES - Go to step 15.
2. NO - Go to step 11.
Measure voltage between ECM/PCM connector terminal B9 and body ground.

Fig 3: Measuring Voltage Between ECM/PCM Connector Terminal B9 & Body Ground

Is there battery voltage?
1. YES - Repair open in the wire between the VTEC oil pressure switch and the ECM/PCM (B9).
2. NO - Go to step 12.
Turn the ignition switch OFF.
Disconnect ECM/PCM connector B (24P).
Check for continuity between ECM/PCM connector terminal B9 and body ground.

Fig 4: Checking Continuity Between ECM/PCM Connector Terminal B9 & Body Ground

Is there continuity?
1. YES - Repair short in the wire between the VTEC oil pressure switch and the ECM/PCM (B9).
2. NO - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
Measure voltage between the VTEC oil pressure switch 2P connector terminals No. 1 and No. 2.

Fig 5: Measuring Voltage Between VTEC Oil Pressure Switch 2-Pin Connector Terminals No. 1 & No. 2

Is there battery voltage?
1. YES - Go to step 16.
2. NO - Repair open in the wire between the VTEC oil pressure switch and G101.
Turn the ignition switch OFF.
Disconnect the VTEC solenoid valve 1P connector.
Check for resistance between the VTEC solenoid valve 1P connector terminal No. 1 and body ground.

Fig 6: Checking Resistance Between VTEC Solenoid Valve 1-Pin Connector Terminal No. 1 & Body Ground

Terminal side of male terminal

Is there 14-30 ohm ?
1. YES - Go to step 19.
2. NO - Replace the VTEC solenoid valve.
Remove the VTEC oil pressure switch (A) and install the special tools as shown, then reinstall the VTEC oil pressure switch.

Fig 7: Removing/Installing VTEC Oil Pressure Switch
Reconnect the VTEC solenoid valve 1P connector and VTEC oil pressure switch 2P connector.
Connect a tachometer.
Start the engine. Hold the engine at 3.000 RPM with no load (in Park or neutral) unit the radiator fan comes on.
Check oil pressure at engine speeds of 1,000, 2,000 and 4,000 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/cm ² , 7 psi)?
1. YES - Go to step 24.
2. NO - Inspect the VTEC solenoid valve (see VTEC Solenoid Valve Test ).
Turn the ignition switch OFF.
Disconnect the VTEC solenoid valve 1P connector.
Attach the battery positive terminal to the VTEC solenoid valve terminal.
Start the engine, and check oil pressure at an engine speed of 3,000 RPM.
Is pressure above 390 kPa (4.0 kgf/cm ² , 57 psi)?
1. YES - Go to step 28.
2. NO - Inspect the VTEC solenoid valve (see VTEC Solenoid Valve Test ).
With the battery positive terminal still connected to the VTEC solenoid valve, measure voltage between ECM/PCM connector terminal B9 and body ground.

Fig 8: Measuring Voltage Between ECM/PCM Connector Terminal B9 & Body Ground

Is there battery voltage above 4,000 RPM?
1. YES - Go to step 29.
2. NO - Replace the VTEC oil pressure switch.
Turn the ignition switch OFF.
Disconnect the battery positive terminal from the VTEC solenoid valve terminal.
Disconnect ECM/PCM connector B (24P).
Check for continuity between ECM/PCM connector terminal B15 and body ground.

Fig 9: Checking Continuity Between ECM/PCM Connector Terminal B15 & Body Ground

Is there continuity?
1. YES - Repair short in the wire between the VTEC solenoid valve and the ECM/PCM (B15).
2. NO - Go to step 32.
Connect the VTEC solenoid valve 1P connector terminal No. 1 and body ground with a jumper wire.

Fig 10: Connecting VTEC Solenoid Valve 1-Pin Connector Terminal No. 1 & Body Ground
Check for continuity between ECM/PCM connector terminal B15 and body ground.

Fig 11: Checking Continuity Between ECM/PCM Connector Terminal B15 & Body Ground

Is there continuity?
1. YES - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
2. NO - Repair short in the wire between the VTEC solenoid valve and the ECM/PCM (B15).