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
Check (Pre-Check)
|
□ Normal
□ DTC
(_______________________________________) □ Freeze Frame Data
|
Check
mode
|
□ Normal
□ DTC
(_______________________________________) □ Freeze Frame
Date
|
|
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
● CHECK OPEN
CIRCUIT
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).

| |
● CHECK SHORT
CIRCUIT
1. Test Method for Short
to Ground Circuit
• |
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.

2. 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
1) |
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.

|
2) |
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) | |