| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES - IMPORT article in GENERAL INFORMATION. |
Circuit Description
The VVT system controls intake valve timing in response to driving conditions. ECM uses input from Crankshaft Position (CKP) sensor and Camshaft Position (CMP) sensor to control Oil Control Valve (OCV). OCV varies oil pressure between 2 circuits changing intake camshaft position as much as 60 degrees of crankshaft angle.
DTC P1656 is set when ECM detects an open or short in OCV circuit. Possible causes are
- Open or short in OCV circuit.
- Faulty OCV.
- Faulty ECM.
Diagnostic Aids
Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.