1998 Lexus SC 400FACTORY OEM SERVICE PROCEDURE

Key Unlock Warning Switch Circuit Test

Ensure key is not in ignition switch. Backprobe for voltage between wireless door lock ECU terminal No. 10 (Yellow wire) and ground. See Figure. If battery voltage exists, go to next test listed in TROUBLE SHOOTINGΒ . If battery voltage does not exist, check circuit between wireless door lock ECU and key unlock warning switch. See WIRING DIAGRAMSΒ . Repair or replace as necessary. Retest system operation.

Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.