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Park/Neutral Position Switch Circuit Test

NOTE: On automatic transmission equipped vehicles, if driver's seat ECU senses transmission is not in Park, it prevents seat from being moved to memorized position.
  1. If shift indicator light for Park position does not come on when transmission is in Park, repair indicator light circuit before continuing. See INSTRUMENT PANELS - GS300 & GS400 article. At driver's seat, remove bolts for front vertical adjuster. Lift front end of seat cushion slightly for access to driver's seat ECU (do not lift too far; harness clamp may come loose).
  2. Remove driver's seat ECU, leaving wiring harness connectors attached. Measure voltage between chassis ground and terminal No. 15 of driver's seat ECU connector "A" (Black/White wire). See Figure.
  3. With transmission in Park, battery voltage should be present. With transmission in any other position, no voltage should be present. If voltage is okay, return to TROUBLE SHOOTING . If voltage is not as specified, repair Black/White wire between driver's seat ECU and park/neutral position switch. See WIRING DIAGRAMS .
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