1990 Lexus LS 400FACTORY OEM SERVICE PROCEDURE

Difficult To Start Cold

  • Check water temperature sensor circuit. See CODE 22 in TESTS W/CODES article.
  • Check starter signal circuit. See CODE 43 in TESTS W/CODES article.
  • Check for vacuum leaks.
  • Check fuel quality.
  • Check idle speed control valve circuit. See IDLE SPEED CONTROL (ISC) VALVE CIRCUIT chart in TESTS W/CODES article.
  • Check EGR system. See CODE 71 in TESTS W/CODES article.
  • Check cold start injector circuit. See COLD START INJECTOR CIRCUIT chart in TESTS W/CODES article.
  • Check intake air temperature sensor circuit. See CODE 24 in TESTS W/CODES article.
  • Check fuel system circuit. See FUEL SYSTEM CIRCUIT chart in TESTS W/CODES article.
  • Check injector circuit. See INJECTOR CIRCUIT chart in TESTS W/CODES article.
  • Check ignition coil. See SYSTEM/COMP TESTS article.
  • Check distributor and spark plugs.
  • Check ECU. See SYSTEM/COMP TESTS article.
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:

  • • 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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