2003 Lexus LS 430FACTORY OEM SERVICE PROCEDURE

Electronic Control

WARNING: This page is about a different car, the 2002 Toyota Highlander. However, it is still accessible from the selected car via links, so may be relevant.
  1. Removal and installation of battery terminal:
    1. Before performing electrical work, disconnect the battery negative (-) terminal cable beforehand so as to prevent burnt-out damage by short.
    2. When disconnecting and installing the terminal cable, turn the ignition switch and lighting switch OFF, and loosen the terminal nut completely. Perform these operations without twisting or prying the terminal.
    3. When the battery terminal is removed, all the memories of the clock, radio, DTCs, etc. will be erased. So before removing it, check them and note them down.
  2. Handling of electronic parts:
    1. Do not open the cover or case of the ECU unless absolutely necessary. (if the IC terminals are touched, the IC may be destroyed by static electricity.)
    2. To disconnect electrical connectors, pull the connector itself, not the wires.
    3. Be careful not to drop electrical components, such as sensors or relays. If they are dropped on a hard floor, they should be replaced and not reused.
    4. When cleaning the engine with steam, protect the electronic components, air filter and emission-related components from water.
    5. Never use an impact wrench to remove or install temperature switches or temperature sensors.
    6. When checking the continuity at the wire connector, insert the tester probe carefully to prevent terminals from bending.
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When to See a Mechanic

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

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

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