2003 Lexus GS 300FACTORY OEM SERVICE PROCEDURE

Problem Symptoms Table

The suspected circuits or parts for each problem symptom are shown in the table below. Use this table to troubleshoot the problem when a "Normal" code is displayed in the diagnostic trouble code check but the problem is still occurring. Numbers in the table indicate the inspection order in which the circuits or parts should be checked.

HINT:

When the problem is not detected by the diagnostic system even though the problem symptom is present, it is considered that the problem is occurring outside the detection range of the diagnostic system, or that the problem is occurring in a system other than the diagnostic system.

EXAMPLE OF PROBLEM SYMPTOM CHART

Symptom Suspect Area
Engine does not crank (Does not start) 1. Starter & Starter relay
No initial combustion (Does not start) 1. ECM power source circuit
2. Fuel pump control circuit
3. Engine Control Module (ECM)
No complete combustion (Does not start) 1. Fuel pump control circuit
Engine cranks normally (Difficult to start) 1. Starter signal circuit
2. Fuel pump control circuit
3. Compression
Cold engine (Difficult to start) 1. Starter signal circuit
2. Fuel pump control circuit
Hot engine 1. Starter signal circuit
2. Fuel pump control circuit
Low idle speed (Poor idle) 1. A/C signal circuit (Compressor circuit)
2. Fuel pump control circuit
Factory Service Tools

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Pair factory procedures with proven DIY tools so the instructions are easier to execute.

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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.

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