Explanation of Troubleshooting Procedures

NOTE: Effective troubleshooting procedures for Multiport Fuel Injection (MFI) system problems are given below.




Procedures
1. Verification of trouble system
- Reproduce the trouble symptoms and verify the characteristics of the trouble and the conditions (engine condition, driving conditions, etc.) under which they are produced.
2. Reading of diagnostic trouble code
- Take a reading of the diagnostic trouble codes and if a diagnostic trouble code is output, locate and correct the trouble while referring to the DIAGNOSTIC CHART (above).
3. Estimation of the causes of trouble and setting of check items
- Referring to the Check Chart, verify the check items and checking order for the trouble symptom.
4. Checking engine control module input and output signals
- Using a scan tool or analyzer, check the input and output signals of the engine control module.
- If the input and output signals are normal, the sensor input actuator control is judged as normal. Then, check the input and output signals of the next check item.
5. Checking engine control module output signals and actuator operation
- Use the scan tool to check the signals output from the engine control module. Also, drive the actuator using the actuator test function to check the actuator operation.
- Use an oscilloscope to check the signals output from the engine control module.
- If the signals output from the engine control module and the operation of the actuator are normal, the actuator control is judged to be normal. Then, check the next check item.
6. Inspect of MFI system component harness
- If the engine control module input/output signals are abnormal, check the MFI system component body harness and repair as necessary.
- After repairing, check the engine control module input/output signals again. If they are normal, proceed to check the input/output signals of the next check item.
7. Inspection of individual MFI system components
- If the body harness is normal but the engine control module input/output signals are abnormal, check individual MFI system components and repair or replace as necessary.
- After repairing or replacement, check the engine control module input/output signals again. If they are normal, proceed to check the input/output signals of the next check item.
8. Re-inspection and repair of trouble
- If the harness inspection and individual component inspection results are normal but the engine control module input/output signals are abnormal, re-examine the causes of the trouble while referring to the troubleshooting hints and the checks and repairs included in other groups.
9. Verification and prevention of reoccurrence after repair
- Carry out tests to see if the same problems occur again and make sure that the same problems will not be repeated.
- Eliminate the causes of the trouble to prevent its reoccurrence.