Diagnosis & Repair

WARNING: This page is about a different car, the 2003 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.

If using OBD-II scan tool, go to step 4. If using hand-held tester, start and warm engine. Connect hand-held tester and select VVT from ACTIVE TEST menu. Check engine speed when operating hand-held tester. When VVT/OCV is off, engine speed should be normal. When VVT/OCV is on, idle should be rough or engine should stall. If system operates okay, check for intermittent problem. If system does not operate okay, go to next step.
Start and warm engine. Disconnect OCV connector. Apply battery voltage to OCV terminals. See Fig 1. If engine runs rough or stalls, go to next step. If engine does not run rough or stall, replace OCV.

Fig 1: Checking OCV Operation
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Turn ignition on. Check waveform between terminals OC1+ and OC1-, and OC2+ and OC2- of ECM connector. Waveform frequency is lengthened as engine speed increases. See Fig 2. If waveform is not to specification, replace ECM. If waveform is to specification, check for open or short circuit in harness and connector between OCV and ECM. Repair as necessary. If harness is okay, check for intermittent problem.

Fig 2: Oil Control Valve (OCV) Signal Waveform
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Start and warm engine. Connect OBD-II scan tool. Disconnect OCV connector. Apply battery voltage to OCV terminals. See Fig 1. If engine runs rough or stalls, go to next step. If engine does not run rough or stall, replace OCV.
Turn ignition on. Check waveform between terminals OC1+ and OC1-, and OC2+ and OC2- of ECM connector. See Fig 2. Waveform frequency is lengthened as engine speed increases. If waveform is not to specification, replace ECM. If waveform is to specification, check for open or short circuit in harness and connector between OCV and ECM. Repair as necessary. If harness is okay, check for intermittent problem.