| CAUTION | If Engine Control Module (ECM) replacement is instructed in following test, always ensure ECM electrical connectors and ground circuits are okay. If either are defective, repair and repeat testing to confirm ECM malfunction. On models equipped with engine immobilizer, 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, or appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT. |
Circuit Description
The Variable Valve Timing (VVT) system controls intake valve timing in response to driving conditions. ECM controls Variable Valve Timing (VVT) Oil Control Valve (OCV) to ensure correct intake valve timing. Engine oil pressure which is controlled by VVT OCV is supplied to VVT controller on front of intake camshaft. VVT controller changes relative position between camshaft and crankshaft. VVT OCV may also be referred to as VVT camshaft timing oil control valve. DTC is set if ECM detects valve timing remains fixed and does not change when engine is at normal operating temperature and engine speed is 400-4000 RPM. Possible causes are
- Incorrect valve timing.
- Defective VVT OCV.
- Defective VVT controller.
- Defective ECM.
Diagnostic Aids
Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.