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Home >> Lexus >> 2002 >> ES 300 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P1656 Or DTC P1663 >> Diagnosis & Repair (Using OBD-II Scan Tool)
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Diagnosis & Repair (Using OBD-II Scan Tool)

  1. Start engine and allow it to idle. Disconnect suspect Oil Control Valve (OCV) and note idle speed. OCV is located in each cylinder head at flywheel side of engine. Engine idle speed should not change. Using jumper wires, apply battery voltage and ground to OCV. Engine should idle rough or stall. If OCV operates as specified, go to next step. If OCV does not operate as specified, replace OCV.
  2. With engine idling, check voltage to OCV. If checking OCV for bank No. 1 (right cylinder head), backprobing, connect oscilloscope between ECM E8 connector terminals No. 13 (Blue/White wire) and No. 14 (Blue/Red wire). See Figure. If checking OCV for bank No. 2 (left cylinder head), backprobing, connect oscilloscope between ECM E8 connector terminals No. 15 (Green/Red wire) and No. 16 (Green/Black wire). On all applications, ensure oscilloscope pattern is as shown. See Figure. As engine speed is increased, waveform frequency ("A") should lengthen. If waveform pattern is as shown, go to next step. If waveform pattern is not as shown, replace ECM.
  3. Check for an open or short circuit in wiring harness between suspect OCV and ECM. Repair wiring harness as necessary. If wiring harness is okay, fault is intermittent.
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