2005 Toyota Avalon XLSFACTORY OEM SERVICE PROCEDURE

Problem Symptoms Table

HINT:

When a malfunction is not confirmed by a DTC (Diagnostic Trouble Code) check and the cause of problem cannot be identified through a basic inspection, troubleshoot according to the priority order indicated in the table below.

PROBLEM SYMPTOMS TABLE - ENGINE CONTROL SYSTEM

Symptoms Suspected Areas
Without Smart Key System: 
Engine does not crank (Does not start)
  • 26. Immobilizer system
  • 27. Starter signal circuit
  • 28. Starter
  • 29. STARTER relay
With Smart Key System: 
Engine does not crank (Does not start)
  1. Immobilizer system
  2. Cranking holding function circuit
  3. Starter signal circuit
  4. Starter
  5. STARTER relay
  6. ECM power source circuit
  7. ECM
No initial combustion (Does not start)
  1. ECM power source circuit
  2. Ignition system
  3. Fuel pump control circuit
  4. Injector
  5. Crank angle sensor
  6. ECM
Engine cranks normally but difficult to start
  1. Electronic Throttle Control System (ETCS)
  2. Fuel pump control circuit
  3. Ignition system
  4. Spark plug
  5. Compression
  6. Injector
  7. Crank angle sensor
Difficult to start with cold engine
  1. Starter signal circuit
  2. Electronic Throttle Control System (ETCS)
  3. Fuel pump control circuit
  4. Spark plug
  5. Ignition system
  6. Injector
  7. Engine coolant temperature sensor
Difficult to start with warm engine
  1. Starter signal circuit
  2. Electronic Throttle Control System (ETCS)
  3. Fuel pump control circuit
  4. Spark plug
  5. Ignition system
  6. Injector
  7. Engine coolant temperature sensor
High engine idling speed (Poor idling)
  1. Electronic Throttle Control System (ETCS)
  2. ECM power source circuit
  3. A/C signal circuit (Compressor circuit)
  4. Acoustic Control Induction System (ACIS)
  5. PCV hose
  6. ECM
Low engine idling speed (Poor idling)
  1. Electronic Throttle Control System (ETCS)
  2. ECM power source circuit
  3. A/C signal circuit (Compressor circuit)
  4. Acoustic Control Induction System (ACIS)
  5. PCV hose
  6. Injector
  7. ECM
Rough idling (Poor idling)
  1. Electronic Throttle Control System (ETCS)
  2. Injector
  3. Ignition system
  4. Compression
  5. Fuel pump control circuit
  6. Spark plug
  7. Acoustic Control Induction System (ACIS)
  8. PCV hose
Hunting (Poor idling)
  1. Electronic Throttle Control System (ETCS)
  2. ECM power source circuit
  3. Fuel pump control circuit
  4. Spark plug
  5. Ignition system
  6. Injector
  7. Acoustic Control Induction System (ACIS)
  8. PCV hose
Hesitation/Poor acceleration (Poor driveability)
  1. Injector
  2. Fuel pump control circuit
  3. Ignition system
  4. Spark plug
  5. Air Intake Control System (AICS)
  6. A/T faulty
Surging (Poor driveability)
  1. Fuel pump control circuit
  2. Spark plug
  3. Ignition system
  4. Injector
Engine stalls soon after starting
  1. Fuel pump control circuit
  2. Electronic Throttle Control System (ETCS)
  3. Crank angle sensor
  4. Spark plug
  5. Ignition system
  6. Injector
Engine stalls during A/C operation
  1. Air conditioning system (Compressor Air)
  2. ECM
Unable/difficult to refuel Refueling valve (canister)
Engine vibrates frequently when idling (Active Control engine Mount (ACM) system does not operate) Active control engine mount circuit
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.