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Home >> Toyota >> 2001 >> Avalon XLS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P1656 Or P1663: Oil Control Valve Malfunction >> 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) harness connector and note idle speed. OCV is located in each cylinder head, underneath lower intake manifold. 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. Connect OCV harness connector. Access ECM behind passenger-side kick panel. See Figure. Using oscilloscope, backprobe ECM harness connector. If checking OCV for bank No. 1 (right cylinder head), connect oscilloscope between terminals No. 18 (Red/White wire) and No. 29 (Red/Blue wire) at ECM harness connector E4. See Figure. If checking OCV for bank No. 2 (left cylinder head), connect oscilloscope between terminals No. 5 (Red wire) and No. 6 (Red/Black wire) at ECM harness connector E4. On all applications, start engine and let idle. Ensure oscilloscope pattern is as shown in illustration. 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 in wiring between suspect OCV and ECM. If problem exists, repair wiring as necessary. If problem does not exist, problem is intermittent. Check component and ECM connections.
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