Engine Diagnostic Flow Chart
GENERAL DESCRIPTIONThis vehicle is equipped with an engine and emission control system which are under control of ECM. The engine and emission control system in this vehicle are controlled by ECM. ECM has an On-Board Diagnostic system which detects a malfunction in this system and abnormality of those parts that influence the engine exhaust emission. When diagnosing engine troubles, be sure to have full understanding of the outline of "On-Board Diagnostic System" (see Description and Operation) and each item in "Precaution in Diagnosing Trouble" (see Diagnostic Strategies) and execute diagnosis according to "ENGINE DIAGNOSTIC FLOW CHART".
There is a close relationship between the engine mechanical, engine cooling system, ignition system, exhaust system, etc. and the engine and emission control system in their structure and operation. In case of an engine trouble, even when the malfunction indicator lamp (MIL, "SERVICE ENGINE SOON" lamp) doesn't turn ON, it should be diagnosed according to the following flow chart.
ENGINE DIAGNOSTIC FLOW CHART
1. CUSTOMER COMPLAINT ANALYSIS
Record details of the problem (failure, complaint) and how it occurred as described by the customer. For this purpose, use of such an inspection form will facilitate collecting information to the point required for proper analysis and diagnosis.
2. DIAGNOSTIC TROUBLE CODE (DTC)/FREEZE FRAME DATA CHECK, RECORD AND CLEARANCE
First, check DTC (including pending DTC), referring to "DTC check" section. If DTC is indicated, print it and freeze frame data or write them down and then clear them by referring to DTC clearance section. DTC indicates malfunction that occurred in the system but does not indicate whether it exists now or it occurred in the past and the normal condition has been restored now. To check which case applies, check the symptom in question according to Step 4 and recheck DTC according to Step 5.
Attempt to diagnose a trouble based on DTC in this step only or failure to clear the DTC in this step will lead to incorrect diagnosis, trouble diagnosis of a normal circuit or difficulty in troubleshooting.
NOTE:
- If only DTC P0461 (Fuel level sensor circuit performance problem) is indicated in this step, perform visual inspection according to Step 3 and then proceed to DTC P0461 Flow Chart.
- For 4A/T vehicle, if only DTC P0705, P0720, P0741, P0743, P0751, P0753, P0756, P0758 or P1875 is indicated in this step, proceed to DIAGNOSIS.
3. VISUAL INSPECTION
As a preliminary step, be sure to perform visual check of the items that support proper function of the engine referring to "Visual Inspection" section.
4. TROUBLE SYMPTOM CONFIRMATION
Based on information obtained in Step 1 Customer complaint analysis and Step 2 DTC/freeze frame data check, confirm trouble symptoms. Also, reconfirm DTC according to "DTC Confirmation Procedure" described in each "DTC FLOW CHART".
5. DTC/FREEZE FRAME DATA RECHECK, RECORD AND CLEARANCE
Refer to "DTC CHECK" for checking procedure.
6. ENGINE BASIC CHECK AND SYMPTOMS DIAGNOSIS TABLE
Perform basic engine check according to the "Engine Basic Check Flow Chart" first. When the end of the flow chart has been reached, check the parts of the system suspected as a possible cause referring to ENGINE DIAGNOSIS TABLE on and based on symptoms appearing on the vehicle (symptoms obtained through steps of customer complaint analysis, trouble symptom confirmation and/or basic engine check) and repair or replace faulty parts, if any.
7. DIAGNOSTIC TROUBLE CODE FLOW CHART
Based on the DTC indicated in Step 5 and referring to "DIAGNOSTIC TROUBLE CODE FLOW CHART" in this section, locate the cause of the trouble, namely in a sensor, switch, wire harness, connector, actuator, ECM or other part and repair or replace faulty parts.
NOTE: For 3A/T vehicle, if only DTC P0740 is indicated in Step 5, diagnose referring to "DIAGNOSTIC TROUBLE CODE FLOW CHART".
8. CHECK FOR INTERMITTENT PROBLEM
Check parts where an intermittent trouble is easy to occur (e.g., wire harness, connector' etc.), referring to "INTERMITTENT AND POOR CONNECTION" and related circuit of DTC recorded in Step 2.
9. FINAL CONFIRMATION TEST
Confirm that the problem symptom has gone and the engine is free from any abnormal conditions. If what has been repaired is related to the malfunction DTC, clear the DTC once and perform DTC confirmation procedure and confirm that no DTC is indicated.