P2647 Cadillac VTEC Oil Pressure Switch Circuit High Voltage

The VTEC system activates the rocker arm oil control solenoid (VTEC solenoid valve) by command from the engine control module (ECM)/powertrain control module (PCM), and it charges/discharges the hydraulic circuit of the VTEC mechanism that switches valve timing between Low and High. The ECM/PCM monitors oil pressure in the hydraulic circuit of the VTEC mechanism using the rocker arm oil pressure switch (VTEC oil pressure switch) downstream of the rocker arm oil control solenoid (VTEC solenoid valve). If there is a difference between the oil pressure condition in the hydraulic circuit that is determined by the ECM/PCM command and the oil pressure condition that is determined by the status of the rocker arm oil pressure switch (VTEC oil pressure switch), the system is considered faulty, and a DTC is stored.