1993 Lexus SC 300 AutomaticFACTORY OEM SERVICE PROCEDURE

Test Preparation

  1. Manufacturer recommends using Check Harness "A" (09990-01000) when using diagnostic code charts to diagnose malfunctions. Check harness "A" is a test harness that is installed between Electronic Control Module (ECM) and ECM connector. Voltage and resistance readings are taken at check harness connectors.
    NOTE: Always check and note diagnostic trouble codes prior to disconnecting ECM connector. Disconnecting ECM connector will erase codes from memory.
  2. To install check harness "A", ensure ignition switch is in the OFF position. Disconnect ECM connector. ECM is located underneath top of passenger-side carpet and is mounted to floor panel. Connect check harness "A" between ECM and ECM connector. Terminal arrangement of check connector is the same as those on the ECM. Proceed to appropriate diagnostic code chart.
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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