How to Proceed With Troubleshooting
HOW TO PROCEED WITH TROUBLESHOOTINGThe Engine Control System broadly consists of the sensors, Engine Control Module (ECM) and actuators. The ECM receives signals from various sensors, judges the operating conditions and determines the optimum injection duration, timing, ignition timing and idle speed.
In general, the Engine Control System is considered to be a very intricate system to troubleshoot. But, the fact is that if you proceed to inspect the circuit one by one following the procedures directed in this section, troubleshooting of this system is not complex.
This section explains the most ideal method of troubleshooting and shows how to carry out the necessary repairs.
1. CUSTOMER PROBLEM ANALYSIS
Using the customer problem analysis check sheet for reference, ask the customer in as much detail as possible about the problem.
2. CHECK AND CLEAR DIAGNOSTIC TROUBLE CODE (PRECHECK)
Before confirming the problem symptom, first check the diagnostic trouble code (Refer to How to Display and Read Diagnostic Trouble Codes) and make a note of any malfunction code which is output, then clear the code (Refer to How to Clear Diagnostic Trouble Codes).
NOTE: Output of the malfunction code indicates that there is a malfunction in the circuit indicated. However, it does not indicate whether the malfunction is still occurring or occurred in the past and returned to normal. In order to determine this, the problem symptoms should be confirmed in step 4 first and the diagnostic trouble code be rechecked in step 6. Accordingly, if troubleshooting is begun based on the malfunction code only in diagnostic trouble code check in step 2, it could result in a misdiagnosis, leading to troubleshooting of circuits which are normal and making it more difficult to locate the cause of the problem.
3. SETTING THE TEST MODE DIAGNOSIS, 4 PROBLEM SYMPTOM CONFIRMATION, 5 SYMPTOM SIMULATION
In order to find out the trouble more quickly, set the diagnosis check in test mode (Refer to How to Display and Read Diagnostic Trouble Codes, Without Scan Tool) and with higher sensing ability of the ECM, confirm the problem symptoms. If the trouble does not reappear, use the symptom simulation method to make sure the trouble is reproduced.
6. DIAGNOSTIC TROUBLE CODE CHECK IN TEST MODE
Check the diagnostic trouble code in test mode. If the malfunction code is output, proceed to step 8. If the normal code is output, proceed to step 7.
7. BASIC INSPECTION
Carry out basic inspection such as the spark check, fuel pressure check, etc. (Refer to Basic Inspection)
8. DIAGNOSTIC TROUBLE CODE CHART
If the malfunction code is displayed, proceed to inspect the circuit indicated by the chart for each code. (Refer to Trouble Code Descriptions)
9. MATRIX CHART OF PROBLEM SYMPTOMS
If the normal code is displayed in the diagnosis in test mode, perform troubleshooting according to the inspection order in the Matrix Chart of Problem Symptoms. Symptom Related Diagnostic Procedures
10. PARTS INSPECTION
When the Matrix Chart of Problem Symptoms instructs to check the part/component, proceed to the appropriate component inspection procedure.
11. CIRCUIT INSPECTION
Determine if the malfunction is in the sensor, actuator, wire harness, connector or the ECM.
12. CHECK FOR MOMENTARY INTERRUPTION
By performing the check for momentary interruption, the place where momentary interruptions or momentary shorts are occurring due to poor contacts can be isolated. (Refer to Check for Momentary Interruption)
13. ADJUSTMENT, REPAIR
After the cause of the problem is located, perform adjustment or repairs by following the inspection and replacement procedures related to the component.
14. CONFIRMATION TEST
After completing adjustment or repairs, confirm not only that the malfunction is eliminated, but also conduct a test drive, etc., to make sure the entire Engine Control System is operating normally.