Component Location
General Description
The CVVT (Continuously Variable Valve Timing) system is installed to the chain sprocket of the intake camshaft. This system controls the intake camshaft to provide the optimal valve timing for every driving condition. The PCM controls the Oil Control Valve(OCV), based on the signals output from mass air flow, throttle position and engine coolant temperature. The CVVT controller regulates the intake camshaft angle using oil pressure through the OCV. As result, the relative position between the camshaft and the crankshaft becomes optimal, and the engine torque improves, fuel economy improves, exhaust emissions decrease under overall driving conditions.
DTC Description
When the enable condition is satisfied, the PCM checks that OCV outputs (Voltage level) are observed when OCVs are commanded. When a OCV output failure is detected, the appropriate fail counter is incremented.
If the failure threshold is exceeded 5 seconds during one diagnostic test(10second), the test is failed and DTC is stored. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
DTC Detecting Condition
Item | Detecting Condition | Possible cause |
DTC Strategy | ? Detects a short to ground or open | ? Poor Connection ? Open in Power Circuit ? Open or short to ground in control circuit ? OCV ? PCM |
Enable Conditions | ? No disabling Faults Present ? Engine Running ? 11V = Ignition Voltage = 16V |
Threshold value | ? Short to ground or open circuit |
Diagnosis Time | ? Continuous (More than 5 seconds failure for every 10 seconds test ) |
MIL On Condition | ? 2 Driving Cycles |
Specification
Resistance (?) | 6.7 ~ 7.7? at 20?(68°F) |
Diagnostic Circuit Diagram
Signal Waveform
Fig.1) Idle
Fig.2) Acceleration
The oil control valve is commanded by a pulse-width-modulated signal from the engine control unit. A duty cycle of zero commands the cam phaser to its default position. A duty cycle of 100% commands the phaser to its maximum phased position. When the phaser must be controlled to an intermediate position, the duty cycle is maintained in the region of the ‘hold position’. This is a medium duty cycle, usually between 35% and 65%, depending on temperature and voltage conditions.