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:
Overhaul
1. Drain brake fluid
Notice:
wash the brake fluid off immediately if it comes into contact with any painted
surface.
2. Remove air cleaner cap sub–assy
3. Remove brake master cylinder sub–assy
disconnect the brake fluid level switch connector from
master cylinder reservoir sub ...
Precaution
Caution:
replace the faulty parts of the seat belt systems (outer belt, inner belt,
bolts, nuts, adjustable shoulder
anchor, tether anchor hardware, sill–bar, etc.).
Seat belt systems not in use at the time of a collision should also be inspected
and replaced if found
to be damaged or wo ...
Inspection procedure
1 Check operation(overdrive)
Drive the vehicle after the engine warms up.
check that overdrive on e off occurs by an operation of the o/d
switch on–off.
2 Inspect terminal voltage(od)
Remove the cruise control ecu assy with the connector
still connected.
tur ...