FixVault
Home › Toyota › 2001 › RAV4 Base, AWD, Automatic › Repair and Diagnosis › Engine Performance › System › Engine Control System Self-Diagnostics › Diagnostic Tests › DTC P1656: Oil Control Valve Circuit Malfunction › Diagnosis & Repair

Diagnosis & Repair

  1. If using Toyota hand-held tester, go to next step. If Toyota hand-held tester is not available, go to step  4.
  2. Connect hand-held tester to Data Link Connector (DLC) No. 3. See Figure. Start engine and warm engine to normal operating temperature. Allow engine to idle.
  3. Select ACTIVE TEST mode and then VVT on hand-held tester to operate the VVT OCV. Note engine idle when VVT OCV is operated by hand-held tester. Engine idle should be normal with VVT OCV off and should become rough or engine may stall when VVT OCV is on. If engine idle does not function as specified, shut engine off. Go to next step. If engine idle is as specified, VVT OCV is functioning properly at this time. DTC may have been set due to intermittent problem in wiring harness or electrical connectors between ECM and VVT OCV.
  4. Disconnect electrical connector at VVT OCV. VVT OCV is located at intake manifold side of cylinder head, near timing chain end of engine. See Figure. Start engine and allow engine to idle. With engine idling, using jumper wires, apply battery voltage and ground to electrical terminals on VVT OCV. Engine should idle rough or stall. If VVT OCV operates as specified, shut engine off. Go to next step. If VVT OCV does not operate as specified, shut engine off. Replace VVT OCV. See VARIABLE VALVE TIMING CAMSHAFT TIMING OIL CONTROL VALVE under VARIABLE VALVE TIMING SYSTEM in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.
  5. Reinstall electrical connector on VVT OCV. Remove glove box and passenger's side kick panel (if necessary) for access to ECM with electrical connectors still installed on ECM. See Figure. Connect oscilloscope between terminals No. 19 (White/Red wire) and No. 29 (White wire) at ECM electrical connector E4. See Figure. This is the OCV+ and OCV- terminals on ECM.
  6. Start engine and allow engine to idle. Ensure VVT OCV signal waveform pattern is as shown in illustration. See Figure. As engine speed is increased, waveform frequency "A" should lengthen. If signal waveform pattern is as shown, shut engine off. Go to next step. If signal waveform pattern is not as shown, shut engine off. Replace ECM.
  7. Check for open and short in wiring harness and electrical connectors between VVT OCV and ECM. See WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, problem is intermittent. Check for defective connections or intermittent problem in wiring between VVT OCV and ECM. If wiring harness or electrical connector is defective, repair as necessary.
About FixVault