Step 2: DTC / Freeze Frame Data Check, Record and
First, check DTC (including pending DTC), referring to
"DTC Check". If DTC is indicated, print it and freeze
frame data or write them down and then clear them by
referring to "DTC Clearance". 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 5 and recheck DTC according to Step 6 and 7.
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.
Step 3 and 4: 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".
Step 5: Trouble Symptom Confirmation
Based on information obtained in "Step 1: Customer
Complaint Analysis: " and "Step 2: DTC / Freeze Frame
Data Check, Record and Clearance: ", confirm trouble
symptoms. Also, reconfirm DTC according to "DTC
Confirmation Procedure" described in each DTC diag.
Step 6 and 7: Rechecking and Record of DTC /
Freeze Frame Data
Refer to "DTC Check" for checking procedure.
Step 8: Engine Basic Inspection and Engine
Perform basic engine check according to "Engine Basic
Inspection" first. When the end of the flow has been
reached, check the parts of the system suspected as a
possible cause referring to "Engine Symptom Diagnosis"
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
Step 9: Troubleshooting for DTC (See each DTC
Based on the DTC indicated in Step 6 or 7 and referring
to the applicable DTC diag. flow, 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.
Step 10: Intermittent Problems Check
Check parts where an intermittent trouble is easy to
occur (e.g., wire harness, connector, etc.), referring to
"Intermittent and Poor Connection Inspection in Section
00" and related circuit of DTC recorded in Step 2.
Engine General Information and Diagnosis:
Step 11: 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 DTC, clear the DTC once,
perform DTC confirmation procedure and confirm that no
DTC is indicated.
Malfunction Indicator Lamp (MIL) Check
1) Turn ON ignition switch (with engine at stop) and
check that MIL (1) lights.
If MIL does not light up (or MIL dims) but engine can
be starting, go to "Malfunction Indicator Lamp Does
Not Come ON with Ignition Switch ON and Engine
Stop (but Engine Can Be Started)" for
If MIL does not light with ignition switch ON and
engine does not start though it is cranked up, go to
"ECM Power and Ground Circuit Check".
2) Start engine and check that MIL turns OFF.
If MIL remains ON and no DTC is stored in ECM, go
to "Malfunction Indicator Lamp Remains ON after
Engine Starts" for troubleshooting.
• There are two types of OBD system
depending on the vehicle specification.
For identification, refer to "Precaution on
On-Board Diagnostic (OBD) System".
• The MIL is turned on when the ECM and/or
TCM detect malfunction(s). Each ECM and
TCM stores diagnostic information as the
diagnostic trouble code (DTC) in its
memory and outputs the DTC to the scan
Therefore, check both of the ECM and TCM
for any DTC with the scan tool because the
DTC stored in ECM and TCM is not read
and displayed at a time. However, each of
the ECM and TCM needs not to be checked
with the generic scan tool because the
DTC stored in ECM and TCM is read and
displayed at a time.