P0026
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 ECM 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
Small particles in the engine oil may cause the oil control valve to bind or otherwise get stuck at certain spool positions. A test is used in this diagnostic to detect a stuck valve spool. A cleaning function is then used to try and free the spool. If unsuccessful, the diagnostic test is failed.
Figure 1. illustrates the principle of the valve stuck diagnostic test. As in the phaser error diagnostic illustration, there are two cases shown in the figure. The case on the left shows a case where the dutycycle is above a calibration threshold, yet the phaser position is near the minimum position. Under normal operation, such a duty cycle command would move the phaser toward its maximum position.The case on the right shows the opposite situation. The duty cycle command is below a threshold, yet the phaser position is near its maximum.
PCM monitors OCV stuck while cam offset is available and Valve cleaning is not in progress.If the PCM detects that CAM position angle is over 20 CAD(Crank Angle Degree) than expected cam positionthat PCM controls the OCV while cam position is in designated crank angle degree, PCM determines that a faultexists and a DTC is stored.
DTC DETECTING CONDITION
SIGNAL WAVEFORM AND DATA
SPECIFICATION
SCHEMATIC DIAGRAM
MONITOR DTC STATUS
1. Check DTC Status
(1) Connect scantool to Data Link Connector(DLC).
(2) IG "ON".
(3) Select "Diagnostic Trouble Codes(DTCs)" mode, and then Press F4(DTAL) to check DTC's information from the DTCs menu
(4) Read "DTC Status" parameter.
(5) Is parameter displayed "Present fault"?
YES
> Go to "Terminal and connector inspection" procedure.
NO
> Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
TERMINAL AND CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES
> Repair as necessary and go to "Verification of Vehicle Repair" procedure
NO
> Go to " Power Circuit Inspection " as follow
POWER CIRCUIT INSPECTION
1. IG "OFF" and disconnect OCV connector.
2. IG "ON" & ENG "OFF".
3. Measure voltage between terminal 2 of OCV harness connector and chassis ground.
Specification : B+
4. Is the measured voltage within specification ?
YES
> Go to " Control Circuit Inspection " procedure.
NO
> Check that Fuse between Main Relay and OCV is open.
> Check open between main relay and OCV.
> Check short to ground between Main Relay and OCV.
> Repair or replace as necessay go to "Verification of Vehicle Repair " procedure.
CONTROL CIRCUIT INSPECTION
1. IG "OFF" and disconnect OCV connector.
2. IG "ON" & ENG "OFF".
3. Measure voltage between terminal 1 of OCV harness connector and chassis ground.
Specification : Approx. below 1V
4. Is the measured voltage within specification ?
YES
> Go to "System Inspection" procedure.
NO
> Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
SYSTEM INSPECTION
1. Visual Inspection
(1) Check oil level is O.K.
(2) Check oil is contaminated.
(3) Check that any oil leakage is occurred around CVVT system.
(4) Has a problem been found ?
YES
> Repair or replace as necessary and then, go to " Verification of Vehicle Repair" procedure.
NO
> Go to "Component Inspection" procedure
COMPONENT INSPECTION
1. OCV Inspection
(1) IG "OFF" & Disconnect OCV connector.
(2) Measure resistance between terminal 1 and 2 of OCV connector (Component Side)
Specification :
(3) Is the measured resistance within specification?
YES
> Go to "Actuation Test" as follow.
NO
> Substitute with a known - good OCV and check for proper operation. If the problem is corrected, replace OCV and go to "Verification of Vehicle Repair" procedure.
2. Actuation Test
(1) IG "OFF" and connect OCV connector
(2) IG "ON" & ENG "OFF"
(3) Check that click sound can be heard when actuation operates with scantool.
(4) Does the OCV operate corectly when actuation operates ?
YES
> Substitute with a known - good PCM and check for proper operation. If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.
NOTE:
There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by PCM.
Before or after testing PCM on the vehicle, use this function to reuse the PCM on the others.
NO
> Substitute with a known - good OCV and check for proper operation. If the problem is corrected, replace OCV and go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions
4. Monitor that all rediness test have been verified as " Complete "
5. Are any DTCs present ?
YES
> Go to the applicable troubleshoooting procedure.
NO
> System is performing to specification at this time.