Circuit Description
VVT system controls intake camshaft to provide optimal valve timing for every driving condition. This control is performed based on signals of conditions such as intake air volume, throttle position and engine coolant temperature. ECM controls Oil Control Valve (OCV), based on signals output from sensors. VVT controller regulates intake camshaft angle using oil pressure through OCV. As a result, relative positions of camshaft and crankshaft become optimal. Engine torque improves, fuel economy improves and exhaust emissions decrease under overall driving conditions. Also, ECM detects actual valve timing using signals from camshaft position sensor and crankshaft position sensor, and performs feedback control. This is how target valve timing is achieved by ECM. See Fig 1. If DTC is set, an open or short is present in oil control valve assembly circuit, camshaft timing oil control valve assembly, and/or ECM.