Basic Troubleshooting
Basic Troubleshooting Guide
Customer Problem Analysis Sheet
Basic Inspection Procedure
Measuring Condition of Electronic Parts' Resistance
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 stated otherwise.
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The measured resistance in except for ambient temperature (20°C,
68°F) is reference value.
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Intermittent Problem Inspection Procedure
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, the 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.
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1. |
Clear Diagnostic Trouble Code (DTC).
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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.
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3. |
Slightly shake the connector and wiring harness vertically and
horizontally.
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4. |
Repair or replace the component that has a problem.
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5. |
Verify that the problem has disappeared with the road test.
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● Simulating Vibration
| 1) |
Sensors and Actuators
: Slightly vibrate sensors, actuators or relays with finger.
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Strong vibration may break sensors, actuators or relays
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| 2) |
Connectors and Harness
: Lightly shake the connector and wiring harness vertically and
then horizontally.
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● Simulating Heat
| 1) |
Heat components suspected of causing the malfunction with a hair
dryer or other heat source.
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• |
DO NOT heat components to the point where they
may be damaged.
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• |
DO NOT heat the ECM directly.
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● Simulating Water Sprinkling
| 1) |
Sprinkle water onto vehicle to simulate a rainy day or a high
humidity condition.
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DO NOT sprinkle water directly into the engine compartment
or electronic components.
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● Simulating Electrical Load
| 1) |
Turn on all electrical systems to simulate excessive electrical
loads (Radios, fans, lights, rear window defogger, etc.).
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Connector Inspection Procedure
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1. |
Handling of Connector
| A. |
Never pull on the wiring harness when disconnecting connectors.
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| B. |
When removing the connector with a lock, press or pull
locking lever.
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| C. |
Listen for a click when locking connectors. This sound
indicates that they are securely locked.
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| D. |
When a tester is used to check for continuity, or to measure
voltage, always insert tester probe from wire harness side.
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| E. |
Check waterproof connector terminals from the connector
side. Waterproof connectors cannot be accessed from harness
side.
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• |
Use a fine wire to prevent damage to the
terminal.
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• |
Do not damage the terminal when inserting
the tester lead.
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2. |
Checking Point for Connector
| A. |
While the connector is connected:
Hold the connector, check connecting condition and locking
efficiency.
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| 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.
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| C. |
Check terminal tightening condition:
Insert a spare male terminal into a female terminal, and
then check terminal tightening conditions.
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| D. |
Pull lightly on individual wires to ensure that each wire
is secured in the terminal.
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3. |
Repair Method of Connector Terminal
| A. |
Clean the contact points using air gun and/or shop rag.
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Never use sand paper when polishing the contact
points, otherwise the contact point may be damaged.
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| B. |
In case of abnormal contact pressure, replace the female
terminal.
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Wire Harness Inspection Procedure
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1. |
Before removing the wire harness, check the wire harness position
and crimping in order to restore it correctly.
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2. |
Check whether the wire harness is twisted, pulled or loosened.
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3. |
Check whether the temperature of the wire harness is abnormally
high.
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4. |
Check whether the wire harness is rotating, moving or vibrating
against the sharp edge of a part.
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5. |
Check the connection between the wire harness and any installed
part.
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6. |
If the covering of wire harness is damaged; secure, repair or
replace the harness.
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Electrical Circuit Inspection Procedure
● Check Open Circuit
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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.
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2. |
Continuity Check Method
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When measuring for resistance, lightly shake the wire
harness above and below or from side to side.
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Specification (Resistance)
1Ω or less → Normal Circuit
1MΩ or Higher → Open Circuit
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| 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.
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| 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).
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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).
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● Check Short Circuit
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1. |
Test Method for Short to Ground Circuit
| A. |
Continuity Check with Chassis Ground
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If short to ground circuit occurs as shown in [FIG. 5], the broken
point can be found by performing Step 2 (Continuity Check Method with
Chassis Ground) as shown below.
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2. |
Continuity Check Method (with Chassis Ground)
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Lightly shake the wire harness above and below, or from
side to side when measuring the resistance.
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Specification (Resistance)
1Ω or less → Short to Ground Circuit
1MΩ or Higher → Normal Circuit
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| 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 following step.
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| 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).
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● Testing For Voltage Drop
This test checks for voltage drop along a wire, or through a connection
orswitch.
| 1) |
Connect the positive lead of a voltmeter to the end of the wire
(or to the side of the connector or switch) closest to the battery.
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| 2) |
Connect the negative lead to the other end of the wire. (or the
other side of the connector or switch)
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| 4) |
The voltmeter will show the difference in voltage between the
two points. A difference, or drop of more than 0.1 volts (50mV in 5V
circuits), may indicate a problem. Check the circuit for loose or dirty
connections.
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Symptom Troubleshooting Guide Chart
Main symptom
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Diagnostic procedure
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Also check for
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Unable to start
(Engine does not turn over)
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| 3. |
Inhibitor switch (A/T) or clutch start switch (M/T)
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Unable to start
(Incomplete combustion)
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| 2. |
Check the fuel pressure
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| 3. |
Check the ignition circuit
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| 4. |
Troubleshooting the immobilizer system
(In case of immobilizer lamp flashing)
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Slipped or broken timing belt
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Difficult to start
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| 2. |
Check the fuel pressure
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| 3. |
Check the ECT sensor and circuit (Check DTC)
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| 4. |
Check the ignition circuit
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Poor idling
(Rough, unstable or incorrect Idle)
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| 1. |
Check the fuel pressure
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| 3. |
Check the long term fuel trim and short term fuel trim
(Refer to CUSTOMER DATASTREAM)
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| 4. |
Check the idle speed control circuit (Check DTC)
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| 5. |
Inspect and test the Throttle Body
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| 6. |
Check the ECT sensor and circuit (Check DTC)
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Engine stall
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| 2. |
Check the fuel pressure
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| 3. |
Check the idle speed control circuit (Check DTC)
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| 4. |
Check the ignition circuit
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| 5. |
Check the CKPS Circuit (Check DTC)
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Poor driving
(Surge)
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| 1. |
Check the fuel pressure
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| 2. |
Inspect and test Throttle Body
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| 3. |
Check the ignition circuit
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| 4. |
Check the ECT Sensor and Circuit (Check DTC)
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| 5. |
Test the exhaust system for a possible restriction
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| 6. |
Check the long term fuel trim and short term fuel trim
(Refer to CUSTOMER DATASTREAM)
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Knocking
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| 1. |
Check the fuel pressure
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| 2. |
Inspect the engine coolant
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| 3. |
Inspect the radiator and the electric cooling fan
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Poor fuel economy
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| 1. |
Check customer's driving habitsIs
· 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?
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| 2. |
Check the fuel pressure
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| 4. |
Test the exhaust system for a possible restriction
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| 5. |
Check the ECT sensor and circuit
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Hard to refuel
(Overflow during refueling)
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| 1. |
Test the canister close valve
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| 2. |
Inspect the fuel filler hose/pipe
· Pinched, kinked or blocked?
· Filler hose is torn
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| 3. |
Inspect the fuel tank vapor vent hose between the EVAP.
canister and air filter
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| 4. |
Check the EVAP. canister
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Malfunctioning gas station filling nozzle (If this problem
occurs at a specific gas station during refueling)
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Special Service Tools
Tool (Number and Name)
Illustration
Application
Fuel Pressure Gauge
(09353-24100)
Measuring t ...
Hyundai Elantra MD/UD: Troubleshooting
