Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2008 Scion tC Base, 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 the problem cannot be identified through a basic inspection, troubleshoot according to the priority order indicated in the table below.
SFI system
SFI SYSTEM - PROBLEM SYMPTOMS CHART
| Symptom | Suspected Area | See |
|---|---|---|
| Engine does not crank (Does not start) | 1. Immobiliser system | SYSTEM DESCRIPTION |
| 2. Starter | INSPECTION | |
| 3. STARTER relay | STARTER RELAY | |
| No initial combustion (Does not start) | 1. ECM power source circuit | ECM POWER SOURCE CIRCUIT |
| 2. ECM VC output circuit | VC OUTPUT CIRCUIT | |
| 3. Fuel pump control circuit | FUEL PUMP CONTROL CIRCUIT | |
| 4. ECM | ECM | |
| Engine cranks normally but difficult to start | 1. Fuel pump control circuit | FUEL PUMP CONTROL CIRCUIT |
| 2. Compression | ON-VEHICLE INSPECTION | |
| Difficult to start with cold engine | 1. Start signal circuit | SYSTEM DIAGRAM |
| 2. Fuel pump control circuit | FUEL PUMP CONTROL CIRCUIT | |
| 3. Spark plug | ON-VEHICLE INSPECTION | |
| 4. Ignition system | ON-VEHICLE INSPECTION | |
| 5. Injector | INSPECTION | |
| Difficult to start with warm engine | 1. Start signal circuit | SYSTEM DIAGRAM |
| 2. Fuel pump control circuit | FUEL PUMP CONTROL CIRCUIT | |
| 3. Spark plug | ON-VEHICLE INSPECTION | |
| 4. Ignition system | ON-VEHICLE INSPECTION | |
| 5. Injector | INSPECTION | |
| High engine idling speed (Poor idling) | 1. A/C signal circuit (compressor circuit) | - |
| 2. ECM power source circuit | ECM POWER SOURCE CIRCUIT | |
| 3. Electronic throttle control system | DTC P2102 THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT LOW; DTC P2103 THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT HIGH | |
| 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 | FUEL PUMP CONTROL CIRCUIT | |
| 3. Electronic throttle control system | DTC P2102 THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT LOW; DTC P2103 THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT HIGH | |
| 4. Air induction system | - | |
| 5. PCV hose | - | |
| Rough Idling (Poor idling) | 1. Compression | ON-VEHICLE INSPECTION |
| 2. Fuel pump control circuit | FUEL PUMP CONTROL CIRCUIT | |
| 3. Electronic throttle control system | DTC P2102 THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT LOW; DTC P2103 THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT HIGH | |
| 4. Air induction system | - | |
| 5. PCV hose | - | |
| Hunting (Poor idling) | 1. ECM power source circuit | ECM POWER SOURCE CIRCUIT |
| 2. Fuel pump control circuit | FUEL PUMP CONTROL CIRCUIT | |
| 3. Spark plug | ON-VEHICLE INSPECTION | |
| 4. Ignition system | ON-VEHICLE INSPECTION | |
| 5. Injector | INSPECTION | |
| 6. Electronic throttle control system | DTC P2102 THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT LOW; DTC P2103 THROTTLE ACTUATOR CONTROL MOTOR CIRCUIT HIGH | |
| 7. Air induction system | - | |
| 8. PCV hose | - | |
| Hesitation/Poor acceleration (Poor driveability) | 1. Fuel pump control circuit | FUEL PUMP CONTROL CIRCUIT |
| 2. A/T faulty* | SYSTEM DESCRIPTION | |
| 3. Spark plug | ON-VEHICLE INSPECTION | |
| 4. Ignition system | ON-VEHICLE INSPECTION | |
| 5. Injector | REMOVAL | |
| Surging (Poor driveability) | 1. Fuel pump control circuit | FUEL PUMP CONTROL CIRCUIT |
| 3. Spark plug | ON-VEHICLE INSPECTION | |
| 4. Ignition system | ON-VEHICLE INSPECTION | |
| 5. Injector | INSPECTION | |
| Engine stalls soon after starting | 1. Fuel pump control circuit | FUEL PUMP CONTROL CIRCUIT |
| 2. Spark plug | ON-VEHICLE INSPECTION | |
| 3. Ignition system | ON-VEHICLE INSPECTION | |
| 4. Injector | INSPECTION | |
| Engine stalls during A/C operation | 1. A/C signal circuit (compressor circuit) | - |
| 2. ECM | ECM | |
| Unable/difficult to refuel | Refueling valve (canister) | - |
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.