2005 Scion tC AutomaticFACTORY 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 (2AZ-FE)

Symptoms Suspected Areas
Engine does not crank (Does not start) 13. Immobilizer system 14. Starter 15. STARTER relay
No initial combustion (Does not start)
  1. ECM power source circuit
  2. Fuel pump control circuit
  3. ECM
Engine cranks normally but difficult to start
  1. Fuel pump control circuit
  2. Compression
Difficult to start with cold engine
  1. Starter signal circuit
  2. Fuel pump control circuit
  3. Spark plug
  4. Ignition system
  5. Injector
Difficult to start with warm engine
  1. Starter signal circuit
  2. Fuel pump control circuit
  3. Spark plug
  4. Ignition system
  5. Injector
High engine idling speed (Poor idling)
  1. A/C signal circuit (compressor circuit)
  2. ECM power source circuit
  3. Electronic throttle control system
  4. Air induction system
  5. PCV hose
Low engine idling speed (Poor idling)
  1. A/C signal circuit (compressor circuit)
  2. Fuel pump control circuit
  3. Electronic throttle control system
  4. Air induction system
  5. PCV hose
Rough idling (Poor idling)
  1. Compression
  2. Fuel pump control circuit
  3. Electronic throttle control system
  4. Air induction system
  5. PCV hose
Hunting (Poor idling)
  1. ECM power source circuit
  2. Fuel pump control circuit
  3. Spark plug
  4. Ignition system
  5. Injector
  6. Electronic throttle control system
  7. Air induction system
  8. PCV hose
Hesitation/Poor acceleration (Poor driveability)
  1. Fuel pump control circuit
  2. A/T faulty(1)
  3. Spark plug
  4. Ignition system
  5. Injector
Surging (Poor driveability)
  1. Fuel pump control circuit
  2. Spark plug
  3. Ignition system
  4. Injector
Engine stalls soon after starling
  1. Fuel pump control circuit
  2. Spark plug
  3. Ignition system
  4. Injector
Engine stalls during A/C operation
  1. A/C signal circuit (Compressor circuit)
  2. ECM
Unable/difficult to refuel Refueling valve (canister)
(1) A/T only
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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.