P0077

P0077

Component Location:

General Description
Different from the existing fixed cam phase angle type, CVVT (Continuously Variable Valve Timing) is the device which varies cam phase angle continuously to be optimum. And with engine oil pressure, it operates. CVVT consists of OCV (Oil Control Valve) and cam phaser. OCV, mounted on cylinder head, controls the amount and direction of oil delivered to cam phaser by oil valve which is connected to a solenoid. Cam phaser, rotating cam phaser rotor with pressure and amount of oil produced by OCV, rotates cam shaft forcefully for or against the rotating direction and finally, cam shaft phase changes. With the appliance of CVVT, engine power,fuel efficiency and the quality of exhaust gas are improved.

DTC Description
When ECM detects short to power in OCV control circuit, ECM sets DTC P0077.

DTC Detecting Condition:

Specification:

Signal Waveform:

Monitor Scantool Data
1. Connect scantool to DLC (Data Link Cable).
2. Warm up the engine to normal operating temperature.
3. Monitor "OCV" parameter on scantool.






4. Is the "OCV" data displayed correctly?

YES - Fault is intermittent caused by poor contact in the sensor's and/or ECM's connector or was repaired and ECM 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.

NO - Go to "Terminal & Connector Inspection" 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 "Control Circuit Inspection" procedure.

Control Circuit Inspection
1. Check short to ground
1. IG "OFF".
2. Disconnect OCV connector.
3. IG "ON" & ENG "OFF".
4. Measure voltage between terminal 1 of OCV harness connector and chassis ground.

Specification : Approx. 3.2 V






5. Is the measured voltage within specification?

YES - Go to "Component Inspection" procedure.

NO - Repair or replace as necessary and then, go to Verification of Vehicle Repair procedure.

Component Inspection
1. Check OCV
1. IG "OFF".
2. Disconnect OCV connector.
3. Measure resistance between terminal 1 and 2 of OCV harness connector. (Component Side)

Specification :






4. Is the measured resistance within specification?

YES - Substitute with a known - good ECM and check for proper operation. If the problem is corrected, replace ECM 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. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Clear the DTCs and Operate the vehicle within DTC Enable conditions in General information.
3. Are any DTCs present?

YES - Go to the applicable troubleshooting procedure.

NO - System is performing to specification at this time.