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Diagnosis & Repair

WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check valve timing. See appropriate article in ENGINES. If no problem exist, go to next step. If problem exists, repair or replace components as necessary.
  2. If Toyota hand-held tester is available, go to next step. If Toyota hand-held tester is not available, go to step  11.
  3. Connect hand-held tester to Data Link Connector (DLC) No. 3 at driver's side of instrument panel. See Figure. Start engine and warm engine to normal operating temperature. Allow engine to idle.
  4. 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 because of a foreign object that was temporarily caught in engine oil system but after a short time system returned to normal.
  5. Remove glove box for access to ECM with electrical connectors still installed on ECM. See Figure. Connect oscilloscope between terminals No. 23 (Yellow/Red wire) and No. 24 (White/Green wire) at ECM electrical connector E7. 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 Fig 1. As engine speed is increased, waveform pattern 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 VVT controller assembly for proper operation. If VVT controller assembly operates properly, go to next step. If VVT controller assembly does not operate properly, replace VVT controller assembly and go to next step.
  8. Check VVT OCV resistance and operation. See VARIABLE VALVE TIMING CAMSHAFT TIMING OIL CONTROL VALVE under VARIABLE VALVE TIMING SYSTEM in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If VVT OCV is okay, go to next step. If VVT OCV is defective, replace VVT OCV and go to next step.
  9. Check for restrictions in VVT OCV, oil filter for VVT OCV and oil passage for VVT OCV. Oil filter for VVT OCV is located behind plug, just below VVT OCV. See Fig 3. If no problem exist, go to next step. If problem exists, repair or replace components as necessary.
  10. Using hand-held tester, clear DTCs from ECM. Start engine and allow engine to idle. Shut engine off. Turn ignition on. Using hand-held tester, check for DTCs. If DTC P1349 exists, replace ECM. If DTC P1349 does not exist, no problem is indicated at this time. DTC may have been set because of a foreign object that was temporarily caught in engine oil system but after a short time system returned to normal.
  11. Start engine and warm engine to normal operating temperature. Allow engine to idle. Note engine idle while disconnecting electrical connector at VVT OCV. VVT OCV is located at intake manifold side of cylinder head, near timing chain end of engine. See Fig 2. Engine idle should not change. 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. Go to step  14.
  12. Reinstall electrical connector on VVT OCV. Remove glove box for access to ECM with electrical connectors still installed on ECM. See Figure. Connect oscilloscope between terminals No. 23 (Yellow/Red wire) and No. 24 (White/Green wire) at ECM electrical connector E7. See Figure. This is the OCV+ and OCV- terminals on ECM.
  13. Start engine and allow engine to idle. Ensure VVT OCV signal waveform pattern is as shown in illustration. See Fig 1. As engine speed is increased, waveform pattern frequency "A" should lengthen. If signal waveform pattern is not as shown, shut engine off. Replace ECM. If signal waveform pattern is as shown, shut engine off. VVT OCV is functioning properly at this time. DTC may have been set because of a foreign object that was temporarily caught in engine oil system but after a short time system returned to normal.
  14. Check VVT controller assembly for proper operation. If VVT controller assembly operates properly, go to next step. If VVT controller assembly does not operate properly, replace VVT controller assembly and go to next step.
  15. Check VVT OCV resistance and operation. See VARIABLE VALVE TIMING CAMSHAFT TIMING OIL CONTROL VALVE under VARIABLE VALVE TIMING SYSTEM in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If VVT OCV is okay, go to next step. If VVT OCV is defective, replace VVT OCV and go to next step.
  16. Check for blockage in VVT OCV, oil filter for VVT OCV and oil passage for VVT OCV. Oil filter for VVT OCV is located behind plug, just below VVT OCV. See Fig 3. If no problem exist, go to next step. If problem exists, repair or replace components as necessary.
  17. Using scan tool, clear DTCs from ECM. Start engine and allow engine to idle. Shut engine off. Turn ignition on. Using scan tool, check for DTCs. If DTC P1349 exists, replace ECM. If DTC P1349 does not exist, no problem is indicated at this time. DTC may have been set because of a foreign object that was temporarily caught in engine oil system but after a short time system returned to normal.
Fig 1: Identifying Variable Valve Timing Oil Control Valve Signal Waveform Pattern
G00023040Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 2: Locating Variable Valve Timing Oil Control Valve
G00023036Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 3: Locating Oil Filter For Variable Valve Timing Oil Control Valve
G00032704Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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