Initial Inspection and Diagnostic Overview

Flow Of Diagnosis:

(1) Verify the complaint
- Reproduce the complaint. Note the problem and the conditions under which the complaint occurs (engine condition, operating state, etc.).

(2) Read diagnostic trouble codes
- Read the diagnostic trouble code and correct the malfunction when a diagnostic trouble code is output, referring to the diagnostic chart.

(3) Estimate cause of trouble and set check item
- Refer to CHECK CHART CLASSIFIED BY PROBLEM SYMPTOMS, determine the check items and procedures to be followed.

(4) Check engine control module input signals
- Use the scan tool or an analyzer to check the signals input to the engine control module.

- If the input signals are normal, the sensor input is judged to be normal. Then, check the next check item.

(5) Check engine control module output signals and actuator operation
- Use the scan tool to check the signals output from the engine control module. Also, force-drive the actuator using the actuator test function to check the actuator operation.

- Use an analyzer 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) Check harnesses of MFI components
- If the input and output signals for the engine control module are not normal, check the body harnesses of the MFI components and repair as necessary.

- After repairing, check the input and output signals for the engine control module again. If they are normal this time, check the input and output signals for the next check item.

(7) Check individual MFI components
- If the body harnesses are normal but the input and output signals for the engine control module are still abnormal, check the MFI components individually and repair or replace as necessary.

- After repair or replacement, check the input and output signals of the engine control module again. If they are normal this time, check the input and output signals of the next check item.

(8) Examine and check causes of trouble and repair
- If the results of the harness check and individual component check are normal but the input and output signals for the engine control module are still abnormal, re-examine the causes of the trouble, referring to the troubleshooting hints. Then, carry out checking and repairing including other groups.

(9) Confirm completion of repair and prevent reoccurrence
- Try to reproduce the trouble symptom to make sure that the symptom does not occur again.

- Remove the true cause of the trouble to prevent its reoccurrence.