2004 Toyota MR2 C56FACTORY OEM SERVICE PROCEDURE

Problem Symptoms Table

When the malfunction is not confirmed in the DTC check and the problem still cannot be confirmed in the basic inspection, use problem symptoms table below and troubleshoot systems in the order listed under "Suspected Area", according to the numbered order given below.

ENGINE CONTROLS SYSTEM - PROBLEM SYMPTOMS TABLE

Symptom Suspected Area Refer To
Engine does not crank (does not start)
  • 8. Starter
  • 9. Starter relay
  • 10. Body ECU
 8. STARTER
9. STARTER RELAY TEST
10. BODY CONTROL SYSTEM - DIAGNOSTICS
No initial combustion (does not start)
  1. ECM power source circuit
  2. Ignition coil with igniter
  3. Fuel control circuit
  4. Injector circuit
  1. ECM POWER SOURCE CIRCUIT 
  2. IGNITION COIL CIRCUITS 
  3. FUEL PUMP CONTROL CIRCUIT 
  4. MISFIRE DETECTED 
No complete combustion (does not start)
  1. Ignition coil with igniter
  2. Fuel control circuit
  3. Injector circuit
  1. IGNITION COIL CIRCUITS 
  2. FUEL PUMP CONTROL CIRCUIT 
  3. MISFIRE DETECTED 
Engine cranks normally (difficult to start)
  1. Starter signal circuit
  2. Ignition coil with igniter
  3. Sparkplug
  4. Compression
  5. Injector circuit
  6. Fuel control circuit
  7. IAC valve circuit (M/T)
  8. Throttle body (Sequential M/T)
  1. STARTER SIGNAL CIRCUIT 
  2. IGNITION COIL CIRCUITS 
  3. IGNITION SYSTEM
  4. COMPRESSION
  5. MISFIRE DETECTED 
  6. FUEL PUMP CONTROL CIRCUIT 
  7. IDLE AIR CONTROL VALVE CIRCUIT 
  8. INSPECTION
Cold engine (difficult to start)
  1. Starter signal circuit
  2. Injector circuit
  3. Ignition coil with igniter
  4. Spark plug
  5. Fuel control circuit
  6. IAC valve circuit (M/T)
  7. Throttle body (Sequential M/T)
  1. STARTER SIGNAL CIRCUIT 
  2. MISFIRE DETECTED 
  3. IGNITION COIL CIRCUITS 
  4. IGNITION SYSTEM
  5. FUEL PUMP CONTROL CIRCUIT 
  6. IDLE AIR CONTROL VALVE CIRCUIT 
  7. INSPECTION
Hot engine (difficult to start)
  1. Starter signal circuit
  2. Injector circuit
  3. Ignition coil
  4. Sparkplug
  5. Fuel control circuit
  6. IAC valve circuit (M/T)
  7. Throttle body (Sequential M/T)
  1. STARTER SIGNAL CIRCUIT 
  2. MISFIRE DETECTED 
  3. IGNITION COIL CIRCUITS 
  4. IGNITION SYSTEM
  5. FUEL PUMP CONTROL CIRCUIT 
  6. IDLE AIR CONTROL VALVE CIRCUIT 
  7. INSPECTION
High engine idle speed (poor idling)
  1. ECM power source circuit
  2. Back-up power source circuit
  3. IAC valve circuit (M/T)
  4. Throttle body (Sequential M/T)
  1. ECM POWER SOURCE CIRCUIT 
  2. SYSTEM VOLTAGE 
  3. IDLE AIR CONTROL VALVE CIRCUIT 
  4. INSPECTION
Low engine idle speed (poor idling)
  1. Injector circuit
  2. Back-up power source circuit
  3. Fuel control circuit
  4. IAC valve circuit (M/T)
  5. Throttle body (Sequential M/T)
  1. MISFIRE DETECTED 
  2. SYSTEM VOLTAGE 
  3. FUEL PUMP CONTROL CIRCUIT 
  4. IDLE AIR CONTROL VALVE CIRCUIT 
  5. INSPECTION
Rough idling (poor idling)
  1. IAC valve circuit
  2. Injector circuit
  3. Fuel control circuit
  4. Ignition coil with igniter
  5. Compression
  1. IDLE AIR CONTROL VALVE CIRCUIT 
  2. MISFIRE DETECTED 
  3. FUEL PUMP CONTROL CIRCUIT 
  4. IGNITION COIL CIRCUITS 
  5. COMPRESSION
Hunting (poor idling)
  1. ECM power source circuit
  2. Fuel control circuit
  3. IAC valve circuit (M/T)
  4. Throttle body (Sequential M/T)
  1. ECM POWER SOURCE CIRCUIT 
  2. FUEL PUMP CONTROL CIRCUIT 
  3. IDLE AIR CONTROL VALVE CIRCUIT 
  4. INSPECTION
Hesitation/Poor acceleration (poor driveability)
  1. Injector circuit
  2. Ignition coil with igniter
  3. Fuel control circuit
  1. MISFIRE DETECTED 
  2. IGNITION COIL CIRCUITS 
  3. FUEL PUMP CONTROL CIRCUIT 
Muffler explosion, after fire (poor driveability)
  1. Ignition coil
  2. Sparkplug
  3. Injector circuit
  1. IGNITION COIL CIRCUITS 
  2. IGNITION SYSTEM
  3. MISFIRE DETECTED 
Surging (poor driveability)
  1. Sparkplug
  2. Injector circuit
  1. IGNITION SYSTEM
  2. MISFIRE DETECTED 
Engine stall (soon after starting)
  1. Fuel control circuit
  2. IAC valve circuit (M/T)
  3. Throttle body (Sequential M/T)
  1. FUEL PUMP CONTROL CIRCUIT 
  2. IDLE AIR CONTROL VALVE CIRCUIT 
  3. INSPECTION
Engine stall (after accelerator pedal depressed)
  1. Injector circuit
  2. IAC valve circuit (M/T)
  3. Throttle body (Sequential M/T)
  4. ECM
  1. MISFIRE DETECTED 
  2. IDLE AIR CONTROL VALVE CIRCUIT 
  3. INSPECTION
  4. PROCEDURE
Engine stall (after accelerator pedal released)
  1. ECM
  2. IAC valve circuit (M/T)
  3. Throttle body (Sequential M/T)
  1. PROCEDURE
  2. IDLE AIR CONTROL VALVE CIRCUIT 
  3. INSPECTION
Engine stall (during A/C operation)
  1. A/C signal circuit (Compressor circuit)
  2. ECM
  1. A/C COMPRESSOR CIRCUIT 
  2. PROCEDURE
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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