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Parking Brake Switch Circuit Test (SC300 M/T)

NOTE: If driver's power seat ECU senses that the parking brake is not applied, it prevents seat from being moved to memorized position.
  1. Start engine. Apply and release parking brake. If parking brake warning light does not come on when parking brake is applied and then go out when it is released, repair warning light circuit before continuing. At driver's seat, remove bolts for front vertical adjuster. Lift front end of seat cushion slightly for access to driver's power seat ECU (DO NOT  lift too far; harness clamp may come loose).
  2. Remove driver's power seat ECU, but leave wiring harness connectors attached. Measure voltage between chassis ground and terminal No. 15 (Gray wire) of driver's power seat ECU connector "A". See Figure.
  3. With parking brake applied, battery voltage should be present. With parking brake released, less than one volt should be present. If voltage is as specified, go to next item listed under TROUBLE SHOOTING .
  4. If voltage is not as specified, repair circuit between driver's power seat ECU and parking brake switch.
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