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:
Rear suspension
Preparation
Sst
Recomended tools
Equipment
Tire & wheel
Preparation
Equipment
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Checking monitor status
Hint:
”monitor result” indicates normal or malfunction of each
component and system when judgment has done.
1. How to read data
Connect the hand–held tester to the dlc 3.
enter ”monitor result” from ”diagnosis / enhanced
obd ii / monitor info / monitor result”
on ...
Catalyst monitor (o2s type)
Preconditions
The monitor will not run unless:
mil is off.
Engine coolant temperature (ect) is 176°f (80 °C) or greater.
Intake air temperature (iat) is 14°f (–10 °C) or greater.*
Notice:
* 2002 and later my vehicles:
the readiness test can be completed in cold ambient c ...