Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
VTEC/Variable Cylinder Management (VCM): Control
Based on engine speed, vehicle speed, engine load, throttle position, and the engine coolant temperature signal sent from various sensors, the powertrain control module (PCM) determines the ON/OFF of each of the rocker arm oil control solenoids.
The PCM switches low lift, high lift, and 3 cylinder operation by controlling the respective solenoid valves. Hydraulic pressure switches are installed in each solenoid circuit for monitoring system malfunction.
| Mode | PCM sends command to the rocker arm oil control solenoid | Rocker arm oil pressure switch (detected oil pressure) | ||||
|---|---|---|---|---|---|---|
| Solenoid A (Bank 1) |
Solenoid B (Bank 1) |
Solenoid A (Bank 2) |
Switch A (Bank 1) |
Switch B (Bank 1) |
Switch A (Bank 2) |
|
| 6 Cylinder Low Lift | OFF | OFF | OFF | ON (Low) | OFF (Low) | ON (Low) |
| 6 Cylinder High Lift | ON | OFF | ON | OFF (High) | OFF (Low) | OFF (High) |
| 3 Cylinder | OFF | ON | OFF | ON (Low) | ON (High) | ON (Low) |
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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