BASIC TROUBLESHOOTING
GUIDE |

CUSTOMER PROBLEM ANALYSIS SHEET
1. |
VEHICLE INFORMATION
(I)
VIN:
|
(II)
Production Date:
|
(III)
Odometer Reading:
(km)
|
|
2. |
SYMPTOMS
□ Unable
to start
|
□ Engine
does not turn over □ Incomplete combustion □ Initial combustion does not
occur
|
□
Difficult to start
|
□ Engine
turns over slowly □ Other_________________
|
□ Poor
idling
|
□ Rough
idling □ Incorrect idling □
Unstable idling (High: ______ rpm, Low:
______rpm) □ Other
__________________________________
|
□ Engine
stall
|
□ Soon
after starting □ After accelerator pedal
depressed □ After accelerator pedal
released □ During A/C ON □ Shifting
from N to D-range □ Other
_______________________________________________
|
□
Others
|
□ Poor
driving (Surge) □ Knocking □ Poor fuel economy □ Back fire □ After fire □ Other
____________________________
|
|
3. |
ENVIRONMENT
Problem
frequency
|
□
Constant □ Sometimes (_________________) □ Once
only □ Other
___________________________________________
|
Weather
|
□ Fine □
Cloudy □ Rainy □ Snowy □ Other
__________________
|
Outdoor
temperature
|
Approx.
_____ °C/°F
|
Place
|
□
Highway □ Suburbs □ Inner City □ Uphill □
Downhill □ Rough road □ Other
___________________________________
|
Engine
temperature
|
□ Cold □
Warming up □ After warming up □ Any
temperature
|
Engine
operation
|
□
Starting □ Just after starting (____ min) □ Idling □
Racing □ Driving □ Constant speed □
Acceleration □ Deceleration □ A/C
switch ON/OFF □ Other
_____________________________
|
|
4. |
MIL/DTC
MIL
(Malfunction Indicator Lamp)
|
□
Remains ON □ Sometimes lights up □ Does not
light
|
DTC
|
□ Normal
□ DTC
(_______________________________________) □ Freeze Frame
Data
|
|
BASIC INSPECTION PROCEDURE
The measured resistance
at high temperature after vehicle running may be high or low. So all
resistance must be measured at ambient temperature (20°C, 68°F), unless
there is any notice.
The measured resistance in except for ambient
temperature (20°C, 68°F) is reference
value. |
Sometimes the most
difficult case in troubleshooting is when a problem symptom occurs but
does not occur again during testing. An example would be if a problem
appears only when the vehicle is cold but has not appeared when warm. In
this case, technician should thoroughly make out a "CUSTOMER PROBLEM
ANALYSIS SHEET" and recreate (simulate) the environment and condition
which occurred when the vehicle was having the issue.
1. |
Clear Diagnostic Trouble Code
(DTC). |
2. |
Inspect connector connection, and check
terminal for poor connections, loose wires, bent, broken or corroded
pins, and then verify that the connectors are always securely
fastened.

|
3. |
Slightly shake the connector and wiring
harness vertically and
horizontally. |
4. |
Repair or replace the component that has a
problem. |
5. |
Verify that the problem has disappeared with
the road test. |
● SIMULATING
VIBRATION
1) |
Sensors and Actuators
: Slightly vibrate sensors, actuators or
relays with finger.
Strong vibration may break sensors,
actuators or
relays | |
2) |
Connectors and Harness
: Lightly shake the connector and wiring
harness vertically and then
horizontally. |
● SIMULATING
HEAT
1) |
Heat components suspected of causing the
malfunction with a hair dryer or other heat sourre.
•
|
DO NOT heat components to the
point where they may be
damaged. |
•
|
DO NOT heat the ECM
directly. | | |
● SIMULATING WATER
SPRINKLING
1) |
Sprinkle water onto vehicle to simulate a
rainy day or a high humidity condition.
DO NOT sprinkle water directly into the
engine compartment or electronic
components. | |
● SIMULATING ELECTRICAL
LOAD
1) |
Turn on all electrical systems to simulate
excessive electrical loads (Radios, fans, lights,
etc.). |
CONNECTOR INSPECTION PROCEDURE
1. |
Handling of Connector
A. |
Never pull on the wiring harness when
disconnecting connectors.

|
B. |
When removing the connector with a lock,
press or pull locking lever.

|
C. |
Listen for a click when locking
connectors. This sound indicates that they are securely
locked.

|
D. |
When a tester is used to check for
continuity, or to measure voltage, always insert tester probe
from wire harness side.

|
E. |
Check waterproof connector terminals
from the connector side. Waterproof connectors cannot be
accessed from harness side.

|
•
|
Use a fine wire to prevent damage
to the terminal. |
•
|
Do not damage the terminal when
inserting the tester
lead. | | |
2. |
Checking Point for Connector
A. |
While the connector is
connected:
Hold the connector, check connecting
condition and locking
efficiency. |
B. |
When the connector is
disconnected:
Check missed terminal, crimped terminal
or broken core wire by slightly pulling the wire
harness.
Visually check for rust, contamination,
deformation and bend. |
C. |
Check terminal tightening
condition:
Insert a spare male terminal into a
female terminal, and then check terminal tightening
conditions. |
D. |
Pull lightly on individual wires to
ensure that each wire is secured in the terminal.

| |
3. |
Repair Method of Connector
Terminal
A. |
Clean the contact points using air gun
and/or shop rag.
Never use sand paper when
polishing the contact points, otherwise the contact
point may be
damaged. | |
B. |
In case of abnormal contact pressure,
replace the female
terminal. | |
WIRE HARNESS INSPECTION PROCEDURE
1. |
Before removing the wire harness, check the
wire harness position and crimping in order to restore it
correctly. |
2. |
Check whether the wire harness is twisted,
pulled or loosened. |
3. |
Check whether the temperature of the wire
harness is abnormally high. |
4. |
Check whether the wire harness is rotating,
moving or vibrating against the sharp edge of a
part. |
5. |
Check the connection between the wire harness
and any installed part. |
6. |
If the covering of wire harness is damaged;
secure, repair or replace the
harness. |
ELECTRICAL CIRCUIT INSPECTION PROCEDURE
1. |
Procedures for Open Circuit
If an open circuit occurs (as seen in [FIG.
1]), it can be found by performing Step 2 (Continuity Check Method)
or Step 3 (Voltage Check Method) as shown below.

|
2. |
Continuity Check Method
When measuring for resistance, lightly
shake the wire harness above and below or from side to
side. |
Specification (Resistance)
1Ω or less → Normal Circuit
1MΩ or Higher → Open
Circuit
|
A. |
Disconnect connectors (A), (C) and
measure resistance between connector (A) and (C) as shown in
[FIG. 2].
In [FIG.2.] the measured resistance of
line 1 and 2 is higher than 1MΩ and below 1 Ω respectively.
Specifically the open circuit is line 1 (Line 2 is normal). To
find exact break point, check sub line of line 1 as described
in next step.

|
B. |
Disconnect connector (B), and measure
for resistance between connector (C) and (B1) and between (B2)
and (A) as shown in [FIG. 3].
In this case the measured resistance
between connector (C) and (B1) is higher than 1MΩ and the open
circuit is between terminal 1 of connector (C) and terminal 1
of connector (B1).

| |
3. |
Voltage Check Method
A. |
With each connector still connected,
measure the voltage between the chassis ground and terminal 1
of each connectors (A), (B) and (C) as shown in [FIG.
4].
The measured voltage of each connector
is 5V, 5V and 0V respectively. So the open circuit is between
connector (C) and (B).

| |
4. |
Test Method for Short to Ground
Circuit
A. |
Continuity Check with Chassis
Ground |
If short to ground circuit occurs as shown in
[FIG. 5], the broken point can be found by performing below Step 2
(Continuity Check Method with Chassis Ground) as shown
below.

|
5. |
Continuity Check Method (with Chassis
Ground)
Lightly shake the wire harness above and
below, or from side to side when measuring the
resistance. |
Specification (Resistance)
1Ω or less → Short to Ground
Circuit
1MΩ or Higher → Normal
Circuit
|
A. |
Disconnect connectors (A), (C) and
measure for resistance between connector (A) and Chassis
Ground as shown in [FIG. 6].
The measured resistance of line 1 and 2
in this example is below 1 Ω and higher than 1MΩ respectively.
Specifically the short to ground circuit is line 1 (Line 2 is
normal). To find exact broken point, check the sub line of
line 1 as described in the folowing step.

|
B. |
Disconnect connector (B), and measure
the resistance between connector (A) and chassis ground, and
between (B1) and chassis ground as shown in [FIG.
7].
The measured resistance between
connector (B1) and chassis ground is 1Ω or less. The short to
ground circuit is between terminal 1 of connector (C) and
terminal 1 of connector (B1).

| |
SYMPTOM TROUBLESHOOTING GUIDE CHART
MAIN SYMPTOM
|
DIAGNOSTIC
PROCEDURE
|
ALSO CHECK FOR
|
Unable to
start (Engine does not turn
over)
|
3. |
Inhibitor switch (A/T) or clutch start
switch (M/T) | |
|
Unable to
start (Incomplete
combustion)
|
2. |
Check the fuel
pressure |
3. |
Check the ignition
circuit |
4. |
Troubleshooting the immobilizer system
(In case of immobilizer lamp
ON) | |
•
|
Slipped or broken timing
belt |
|
Difficult to
start
|
2. |
Check the fuel
pressure |
3. |
Check the ECT sensor and circuit (Check
DTC) |
4. |
Check the ignition
circuit | |
|
Poor
idling (Rough, unstable or incorrect
Idle)
|
1. |
Check the fuel
pressure |
3. |
Check the long term fuel trim and short
term fuel trim (Refer to CUSTOMER
DATASTREAM) |
4. |
Check the ISCA and ISCA circuit (Check
DTC) |
5. |
Inspect and test the Throttle
Body |
6. |
Check the ECT sensor and circuit (Check
DTC) | |
|
Engine
stall
|
2. |
Check the fuel
pressure |
3. |
Check the ISCA and ISCA circuit (Check
DTC) |
4. |
Check the ignition
circuit |
5. |
Check the CKPS Circuit (Check
DTC) | |
|
Poor
driving (Surge)
|
1. |
Check the fuel
pressure |
2. |
Inspect and test Throttle
Body |
3. |
Check the ignition
circuit |
4. |
Check the ECT Sensor and Circuit (Check
DTC) |
5. |
Test the exhaust system for a possible
restriction |
6. |
Check the long term fuel trim and short
term fuel trim (Refer to CUSTOMER
DATASTREAM) | |
|
Knocking
|
1. |
Check the fuel
pressure |
2. |
Inspect the engine
coolant |
3. |
Inspect the radiator and the electric
cooling fan |
|
|
Poor fuel
economy
|
1. |
Check customer's driving
habits |
•
|
Is A/C on full time or the
defroster mode on? |
•
|
Are tires at correct
pressure? |
•
|
Is excessively heavy load being
carried? |
•
|
Is acceleration too much, too
often? | |
2. |
Check the fuel
pressure |
4. |
Test the exhaust system for a possible
restriction |
5. |
Check the ECT sensor and
circuit | |
|
Hard to
refueling (Overflow during
refueling)
|
1. |
Test the canister close
valve |
2. |
Inspect the fuel filler
hose/pipe |
•
|
Pinched, kinked or
blocked? |
|
3. |
Inspect the fuel tank vapor vent hose
between the EVAP. canister and air
filter |
4. |
Check the EVAP.
canister | |
•
|
Malfunctioning gas station filling
nozzle (If this problem occurs at a specific gas station
during
refueling) | |