2005 Lexus IS 300 Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Problem Symptoms Table

PROBLEM SYMPTOMS TABLE - ENGINE CONTROL SYSTEM

Symptom Suspect Area
Engine does not crank (Does not start)
  • 14. Starter
  • 15. Starter relay
No initial combustion (Does not start)
  1. Engine immobilizer system
  2. ECM power source circuit
  3. Fuel pump control circuit
No complete combustion (Does not start)
  1. Fuel pump control circuit
Under normal condition (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 (Difficult to start)
  1. Starter signal circuit
  2. Fuel pump control circuit
High engine idle speed (Poor idling)
  1. A/C signal circuit (Compressor circuit)
  2. ECM power source circuit
Low engine idle speed (Poor idling)
  1. A/C signal circuit (Compressor circuit)
  2. Fuel pump control circuit
Rough idling (Poor idling)
  1. Compression
  2. Fuel pump control circuit
Hunting (Poor idling)
  1. ECM power source circuit
  2. Fuel pump control circuit
Hesitation/Poor acceleration (Poor driveability)
  1. Fuel pump control circuit
  2. A/T faulty
Surging (Poor driveability)
  1. Fuel pump control circuit
Soon after starting (Engine stall)
  1. Engine immobilizer system
  2. Fuel pump control circuit
During A/C operation (Engine stall)
  1. A/C signal circuit (Compressor circuit)
  2. ECM
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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