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Home >> Lexus >> 2000 >> SC 400 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P1656 Or P1663: Oil Control Valve (OCV) >> Diagnosis & Repair (Using Lexus Scan Tool)
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Diagnosis & Repair (Using Lexus Scan Tool)

  1. Start and run engine. Allow engine to reach normal operating temperature. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. See Figure. Select VVT from scan tool ACTIVE TEST menu. Using scan tool, turn OCV on and off. If idle speed is normal with OCV off and engine idles rough or stalls when OCV is on, VVT is functioning properly at this time. Fault is intermittent. DTC may have been set because of a foreign object that was temporarily caught in the engine oil system but after a short time system returned to normal. If idle speed does not function as specified, go to next step.
  2. With engine running. Disconnect suspect OCV connector. Connect fused jumper wires between positive battery terminal and OCV connector terminal No. 1, and negative battery terminal and OCV connector terminal No. 2. See Figure. Engine should idle rough or stall. If OCV operates as specified, go to next step. If OCV does not operate as specified, replace OCV.
  3. Start engine. Backprobe ECM connector. For left OCV, using oscilloscope, check waveform pattern between terminals No. 19 (Red/Black wire) and No. 20 (Black/White wire) at ECM E15 connector. See Figure. For right OCV, using oscilloscope, check waveform pattern between terminals No. 19 (White/Red wire) and No. 28 (Green/Yellow wire) at ECM E18 connector. See Figure. Slowly increase engine speed. Waveform frequency "A" should lengthen as engine speed increases. See Figure. If readings are not as specified, replace ECM and retest. If readings are as specified, go to next step.
  4. Check for an open or short circuit and connector in wire harness between suspect OCV and ECM E2 or ECM E18 connector. Repair as necessary. If circuit and connector are okay, problem is intermittent.
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