Basic Troubleshooting Guide
Customer Problem Analysis Sheet
Basic Inspection Procedure
Measuring Condition of Electronic Parts' Resistance
The resistance measured at high temperature after running the
vehicle 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 measure resistance at temperatures other than ambient temperature (20°C, 68°F) is reference value. |
Intermittent Problem Inspection Procedure
In terms of troubleshooting, the most difficult case is that a
symptom which caused trouble cannot be simulated during testing. For
example, a symptom appears if the vehicle is cold but not appear if it
is warm. In this case, the service technician should understand the
“Customer Problem Analysis Sheet” and reproduce the environment and
condition in which the vehicle showed the symptom.
| 1. |
Clear Diagnostic Trouble Code (DTC). |
| 2. |
Inspect the connector, and check the terminal for poor
connections, loose wires and bent, broken or corroded pins. And check
whether the connectors are securely fastened. 
|
| 3. |
Slightly shake the connector and wiring harness up and down or from side to side. |
| 4. |
Repair or replace the problematic component. |
| 5. |
Confirm that the symptom has disappeared after performing the road test. |
? Simulating Vibration
| 1) |
Sensors and Actuators
: Slightly vibrate sensors, actuators or relays by hand.
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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 up and down or from side to side. |
? Simulating Heat
| 1) |
Heat components suspected of causing the malfunction with a hair dryer or other heat source.
| • |
DO NOT heat components to the point where they may be damaged. |
| • |
DO NOT heat the ECM directly. |
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? Simulating Water Sprinkling
| 1) |
With a hair dryer or other devices, apply heat to the components suspected of being the cause of the malfunction.
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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.). |
Connector Inspection Procedure
| 1. |
Handling of Connector
| A. |
When disconnecting the connectors, pull on the connector, not the wiring harness. 
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| B. |
When removing the connector with a lock, press or pull locking lever. 
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| C. |
When connecting the connectors, check whether a clicking
sound is heard to make sure that the connectors are securely connected. 
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| D. |
When a tester is used to check for continuity, or to measure voltage, always insert the test probe in the wiring harness side. 
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| E. |
Check waterproof connector terminals from the connector side.
Waterproof connectors cannot be accessed through the harness side. 
| • |
Use a fine wire to prevent the terminal from being damaged. |
| • |
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. |
| 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 sagging. |
| 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. 
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| 3. |
Repair Method of Connector Terminal
| A. |
Clean the contact points using air gun and/or a cotton towel.
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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
| 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, sagging 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. |
Check whether the covering of wire harness is damaged. |
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. 
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| 2. |
Continuity Check Method
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When measuring the resistance, lightly shake the wire harness up and down or from side to side. |
Specification (Resistance)
1? or less > Normal Circuit
1M? 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].
If the measured resistance of line 1 and 2 is higher than 1M
? and 1 ?, respectively in [FIG. 2], the line 1 is the open circuit
(line 2 is normal). To find the exact break point, inspect the sub line
of line 1 (the next step). 
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| B. |
Disconnect connector (B), and measure resistance between connector (C) and (B1) and between (B2) and (A) as shown in [FIG. 3].
If the measured resistance between connector (C) and (B1) is
1M ? or higher, and the resistance between (B2) and (A) is 1 ? or
lower, line 1 of connector (C) and line 1 of connector (B1) are open
circuits. 
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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
| 1. |
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 Step 2 (Continuity Check Method
with Chassis Ground) as shown below. 
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| 2. |
Continuity Check Method (with Chassis Ground)
|
Lightly shake the wire harness up and down, or from side to side when measuring the resistance. |
Specification (Resistance)
1? or less > Short to Ground Circuit
1M? or Higher > Normal Circuit
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| A. |
Disconnect connectors (A), (C) and measure 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 ? and higher than 1M? 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 1? 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 or switch.
| 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. |
| 2) |
Connect the negative lead to the other end of the wire. (or the other side of the connector or switch) |
| 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 any dirt and
loose connections. |
Symptom Troubleshooting Guide Chart
Main symptom
| Diagnostic procedure
| Also check for
|
Unable to start
(Engine does not turn over)
|
| 1. |
Test the battery.
(Refer to Engine Electrical System - "Battery") |
| 2. |
Test the starter.
(Refer to Engine Electrical System - "Starter") |
| 3. |
Inhibitor switch (A/T) or clutch start switch (M/T) |
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Unable to start
(Incomplete combustion)
|
| 1. |
Test the battery.
(Refer to Engine Electrical System - "Battery") |
| 2. |
Check the fuel pressure.
(Refer to Fuel Delivery System - Repair procedures - "Fuel Pressure Test") |
| 3. |
Check the ignition circuit.
(Refer to Engine Electrical System - "Ignition System") |
| 4. |
Troubleshooting the immobilizer system.
(Refer to Body Electrical System - "Immobilizer System")
(In case of immobilizer lamp flashing) |
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| • |
Slipped or broken timing belt |
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Difficult to start
|
| 1. |
Test the battery.
(Refer to Engine Electrical System - "Battery") |
| 2. |
Check the fuel pressure.
(Refer to Fuel Delivery System - Repair procedures - "Fuel Pressure Test") |
| 3. |
Check the ECT sensor and circuit (Check DTC) |
| 4. |
Check the ignition circuit.
(Refer to Engine Electrical System - "Ignition System") |
|
|
Poor idling
(Rough, unstable or incorrect Idle)
|
| 1. |
Check the fuel pressure.
(Refer to Fuel Delivery System - Repair procedures - "Fuel Pressure Test") |
| 2. |
Check the Injector.
(Refer to Engine Control System - "Injector") |
| 3. |
Check the long term fuel trim and short term fuel trim
(Refer to CUSTOMER DATASTREAM) |
| 4. |
Check the idle speed control circuit (Check DTC) |
| 5. |
Inspect and test the Throttle Body |
| 6. |
Check the ECT sensor and circuit (Check DTC) |
|
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Engine stall
|
| 1. |
Test the battery.
(Refer to Engine Electrical System - "Battery") |
| 2. |
Check the fuel pressure.
(Refer to Fuel Delivery System - Repair procedures - "Fuel Pressure Test") |
| 3. |
Check the idle speed control circuit (Check DTC) |
| 4. |
Check the ignition circuit.
(Refer to Engine Electrical System - "Ignition System") |
| 5. |
Check the CKPS Circuit (Check DTC) |
|
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Poor driving
(Surge)
|
| 1. |
Check the fuel pressure.
(Refer to Fuel Delivery System - Repair procedures - "Fuel Pressure Test") |
| 2. |
Inspect and test Throttle Body |
| 3. |
Check the ignition circuit.
(Refer to Engine Electrical System - "Ignition System") |
| 4. |
Check the ECT Sensor and Circuit (Check DTC) |
| 5. |
Test the exhaust system for a possible restriction.
(Refer to Engine Mechanical System - "Exhaust Manifold") |
| 6. |
Check the long term fuel trim and short term fuel trim.
(Refer to CUSTOMER DATASTREAM) |
|
|
Knocking
|
| 1. |
Check the fuel pressure.
(Refer to Fuel Delivery System - Repair procedures - "Fuel Pressure Test") |
| 2. |
Inspect the engine coolant.
(Engine Mechanical System - "Radiator") |
| 3. |
Inspect the radiator and the electric cooling fan.
(Engine Mechanical System - "Radiator") |
| 4. |
Check the spark plugs.
(Refer to Engine Electrical System - "Ignition System") |
|
|
Poor fuel economy
|
| 1. |
Check customer's driving habits
· A/C on full time or the defroster mode on?
· Are tires at proper pressure?
· Is heavy load being excessively carried?
· Is acceleration too much, too often? |
| 2. |
Check the fuel pressure.
(Refer to Fuel Delivery System - Repair procedures - "Fuel Pressure Test") |
| 3. |
Check the injector.
(Refer to Engine Control System - "Injector") |
| 4. |
Test the exhaust system for a possible restriction |
| 5. |
Check the ECT sensor and circuit |
|
|
Hard to refuel
(Overflow during refueling)
|
| 1. |
Test the canister close valve.
(Refer to Engine Control System - "Canister Close Valve) |
| 2. |
Inspect the fuel filler hose/pipe
· Pinched, kinked or blocked?
· Filler hose is torn |
| 3. |
Inspect the fuel tank vapor vent hose between the EVAP. canister and air filter |
| 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
