2000 Lexus SC 400FACTORY OEM SERVICE PROCEDURE

Sensor Power Source Circuit

  1. Turn ignition off. Remove tilt and power telescopic ECU with wiring harness connector attached. Turn ignition on. Turn ignition on. Using a voltmeter, measure voltage by backprobing rear of 18-pin ECU harness connector T10 between terminals No. 17 (Red/White wire) and No. 5 (Brown wire). See Figure. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, go to step  3.
  2. Check wiring harness and connectors for an open between tilt and power telescopic ECU, tilt and power telescopic unit (combination switch) and telescopic position sensor. See WIRING DIAGRAMS . Repair or replace as necessary. If wiring harness and connectors are okay, go to next test listed in SYMPTOM DIAGNOSIS  table under TROUBLE SHOOTING.
  3. Check wiring harness and connectors for a short between tilt and power telescopic ECU, tilt and power telescopic unit (combination switch) and telescopic position sensor. See WIRING DIAGRAMS . Repair or replace as necessary. If wiring harness and connectors are okay, go to next test listed in SYMPTOM DIAGNOSIS  table under TROUBLE SHOOTING.
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