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Diagnosis & Repair (Using OBD-II Scan Tool)

  1. Access ECM at left front of engine compartment. Backprobing ECM connector, measure voltage between ground and following terminal:
    • On GS300, terminal No. 2 (Black wire) at ECM connector E5. See Figure.
    • On IS300, terminal No. 2 (Black wire) at ECM connector E4. See Figure.
    • On GS430, terminal No. 12 (Black wire) at ECM connector E6. See Figure.
    • On LS430, terminal No. 12 (Blue/Orange wire) at ECM connector E3. See Figure.

    On all models, go to next step.

  2. Turn ignition switch to START position. With starter being cranked, voltage should be 6 volts or more. If voltage is not as specified, go to next step. If voltage is as specified, no problem is indicated at this time. Diagnose by symptom. See TROUBLE SHOOTING - NO CODES article.
  3. Check for open in wiring harness between ECM and starter relay. See WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest.
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