LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 1998 >> SC 400 >> Repair and Diagnosis (Single Page) >> Body & Frame >> Seats - Power W/Memory >> System Testing >> Ignition Switch Circuit Test
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Ignition Switch Circuit Test

NOTE: If driver's seat ECU senses ignition is not turned on, it prevents seats from being operated.
  1. 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). Remove driver's seat ECU, leaving wiring harness connectors attached. Measure voltage between chassis ground and terminal No. 7 at driver's seat ECU connector "A" (Black/Red wire). See Figure.
  2. With ignition on, battery voltage should be present. With ignition off, no voltage should be present. If voltage is as specified, return to TROUBLE SHOOTING . If voltage is not as specified, check ECU-IG (15-amp) fuse, located in junction block No. 1 under left kick panel. If ECU-IG fuse is blown, check for short to ground. If ECU-IG fuse is okay, repair circuit between driver's seat ECU and battery.
scientia non olet · About LEMON Manuals