Toyota Corolla (E120) 2002–2008 Repair Manual / Diagnostics / Sfi system / Camshaft position ”a” actuator
circuit / Circuit description
Toyota Corolla (E120): Circuit description
The variable valve timing (vvt) system includes the ecm, the oil control valve (ocv) and the vvt controller.
The ecm sends a target ”duty–cycle” control signal to the ocv. This control signal, applied to the ocv, regulates the oil pressure supplied to the vvt controller. Camshaft timing control is performed based on engine operation conditions such as the intake air volume, throttle position and engine coolant temperature.
The ecm controls the ocv, based on the signals output from the sensors. The vvt controller regulates the intake camshaft angle using oil pressure through the ocv. As result, the relative position between the camshaft and the crankshaft is optimized, and the engine torque improves, fuel economy improves, and exhaust emissions decrease under overall driving conditions. Also, the ecm detects the actual valve timing using signals from the camshaft position sensor and the crankshaft position sensor, and performs the feedback control. This is how target valve timing is verified by the ecm.
Monitor description
After the ecm sends the ”target” duty–cycle signal to the ocv, the ecm monitors the ocv current to establish an ”actual” duty–cycle. The ecm detects a malfunction and sets a dtc when the actual duty–cycle ratio varies from the target duty–cycle ratio.
Monitor strategy
Typical enabling conditions
Typical malfunction thresholds
Component operating ra
Wiring diagram
Other materials:
Lubrication system
On–vehicle inspection
1. Check engine oil level
after warming up the engine and then 5 minutes after the engine
stops, oil level should be between
the ”l” and ”f” marks on the oil level gage.
If low, check for leakage and add oil up to the ”f” mark.
Notice:
do not ...
Precaution
1. Do not handle refrigerant in an enclosed
area or near an open flame
2. Always wear eye protection
3. Be careful not to get liquid refrigerant in your eyes or on your skin
If liquid refrigerant gets in your eyes or on your skin.
wash the area with lots of cool water.
Cautio ...
Oil filter sub–assy
Replacement
Caution:
prolonged and repeated contact with mineral oil will result in the
removal of natural fats from
the skin, leading to dryness, irritation and dermatitis. In addition, used
engine oil contains potentially
harmful contaminants which may cause skin cancer.
Exercise ...