| 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 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 Variable Valve Timing (VVT) sensor to control Oil Control Valve (OCV). OCV varies oil pressure between 2 circuits changing intake camshaft position in relation to crankshaft angle.
DTC is set when ECM detects an open or short in OCV circuit. DTC P1656 is for bank No. 1 OCV. DTC P1663 is for bank No. 2 OCV. 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.