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Home >> Lexus >> 1999 >> SC 400 >> Repair and Diagnosis >> Steering >> Steering Column >> Power Tilt Steering Column Systems >> Circuit Tests >> Door Courtesy Switch Circuit
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Door Courtesy Switch Circuit

  1. Open driver's door and ensure door courtesy light illuminates. If door courtesy light illuminates, go to next step. If door courtesy light does not illuminate, check and repair door courtesy light circuit. See appropriate wiring diagram in ILLUMINATION/INTERIOR LIGHTS article.
  2. Turn ignition off. Remove tilt and telescopic ECU with wiring harness connector attached. Using a voltmeter, measure voltage by backprobing rear of 18-pin ECU connector T10 between terminal No. 2 (Red/Black wire) and ground. See Figure. With driver's door closed, voltage should be 10-14 volts. With driver's door open, voltage should be less than one volt. If voltage is not as specified, go to next step. If voltage is as specified, go to next test listed in SYMPTOM DIAGNOSIS  table under TROUBLE SHOOTING.
  3. Check and repair open wiring harness between tilt and telescopic ECU and driver's door courtesy switch. See WIRING DIAGRAMS .
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