Toyota Celica 2005, Repair Manual

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DIC6I − 02
A21409
Mass Air Flow Sensor
Crankshaft Position Sensor
Actual Valve Timing
Correction
Target Valve Timing
Feedback
Duty Control
ECM
Camshaft Timing
Oil Control
Valve (OCV)
Vehicle Speed Signal
Engine Coolant Temp. Sensor
Throttle Position Sensor
Camshaft Position Sensor
DI − 48
− DIAGNOSTICS ENGINE (1ZZ − FE)
2005 CELICA (RM1131U)
CIRCUIT INSPECTION
DTC P0010 Camshaft Position ”A” Actuator circuit
(Bank 1)
CIRCUIT DESCRIPTION
The Variable Valve Timing (VVT) system includes the ECM, the Oil Control Valve (OCV) and the VVT control-
ler. The ECM sends a target ”duty
− cycle” control signal to the OCV. This control signal, sent to the OCV,
regulates the oil pressure applied to the VVT controller. Camshaft timing control is performed based on en-
gine 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 a result, the relative position between the cam-
shaft and the crankshaft is optimized, and the engine torque and fuel economy improve, and exhaust emis-
sions 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.
DTC No. DTC Detecting Condition Trouble Area
P0010
Open or short in Oil Control Valve (OCV) circuit
(1 trip detection logic)
S Open or short in oil control valve circuit
S Oil control valve
S ECM
MONITOR DESCRIPTION
After the ECM sends the ”target” duty − cycle signal to the OCV (Oil Control Valve), the ECM monitors the
OCV current to establish an ”actual” duty − cycle. When the actual duty − cycle ratio varies from the forget
duty − cycle ratio, the ECM sets a DTC.
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