Troubleshooting Of Each Problem Symptom

The problem is still occurring in a place other than the diagnostic circuit (the DTC displayed first is either for a past problem or a secondary problem). 4. SYMPTOM SIMULATION HINT:

The most difficult case in troubleshooting is when no problem symptoms occur. In such a case, a thorough problem analysis must be carried out. A simulation of the same or similar conditions and environment in which the problem occurred in the customer's vehicle should be carried out. No matter how much skill or experience a technician has, troubleshooting without confirming the problem symptoms will lead to important repairs being overlooked and mistakes or delays.

Vibrate Slightly

Vibrate Slightly

Shake Slightly ^

Vibrate Slightly

Shake Slightly ^

Vibrate Slightly

For example: With a problem that only occurs when the engine is cold or as a result of vibration caused by the road during driving, the problem can never be determined if the symptoms are being checked on a stationary vehicle or on a vehicle with a warmed-up engine. Vibration, heat or water penetration (moisture) is difficult to reproduce. The symptom simulation tests below are effective substitutes for the conditions and can be applied on a stationary vehicle.

Important points in the symptom simulation test: In the symptom simulation test, the problem symptoms as well as the problem area or parts must be confirmed. First, narrow down the possible problem circuits according to the symptoms. Then, connect the tester and carry out the symptom simulation test, judging whether the circuit being tested is defective or normal. Also, confirm the problem symptoms at the same time. Refer to the problem symptoms table for each system to narrow down the possible causes.

(a) VIBRATION METHOD:

When a malfunction seems to occur as a result of vibration.

(1) PART AND SENSOR

Apply slight vibration with a finger to the part of the sensor suspected to be the cause of the problem, and check whether or not the malfunction occurs. NOTICE:

Applying strong vibration to relays may open them.

(2) CONNECTORS

Slightly shake the connector vertically and horizontally.

(3) WIRE HARNESS

Slightly shake the wire harness vertically and horizontally.

HINT:

The connector joint and fulcrum of the vibration are the major areas that should be checked thoroughly.

When a malfunction seems to occur when the area in question is heated.

(1) Heat the component that is the possible cause of the malfunction with a hair dryer or similar device. Check if the malfunction occurs. NOTICE:

• Do not heat to more than 60°C (140°F). Exceeding this temperature may damage components.

• Do not apply heat directly to the parts in the ECU.

(c) WATER SPRINKLING METHOD:

When a malfunction seems to occur on a rainy day or in high-humidity.

(1) Sprinkle water onto the vehicle and check if the malfunction occurs. NOTICE:

• Never sprinkle water directly into the engine compartment. Indirectly change the temperature and humidity by spraying water onto the front of the radiator.

• Never apply water directly onto the electronic components.

HINT:

If the vehicle has or had a water leakage problem, the leakage may have damaged the ECU or connections. Look for evidence of corrosion or short circuits. Proceed with caution during water tests.

(d) HIGH ELECTRICAL LOAD METHOD: When a malfunction seems to occur when the electrical load is excessive.

(1) Turn on the heater blower, headlight, rear window defogger and all other electrical loads. Check if the malfunction reoccurs. 5. DIAGNOSTIC TROUBLE CODE CHART Look for output Diagnostic Trouble Codes (DTCs) (from the DTC checks) in the appropriate section's Diagnostic Trouble Code Chart. Use the chart to determine the trouble area and the proper inspection procedure. A description of each of the chart's columns are below.

Item

Description

DTC No.

Indicates the diagnostic trouble code

Detection Item

Indicates the system or details of the problem

Trouble Area

Indicates the suspected areas of the problem

See Page

Indicates the page where the inspection procedures for each circuit are to be found, or gives instruction for checking and repairs

6. PROBLEM SYMPTOMS TABLE

When a "Normal" code is output during a DTC check but the problem is still occurring, use the Problem Symptoms Table. The suspected areas (circuits or parts) for each problem symptom are in the table. The suspected areas are listed in order of probability. A description of each of the chart's columns is below. HINT:

In some cases, the problem is not detected by the diagnostic system even though a problem symptom is present. It is possible that the problem is occurring outside the detection range of the diagnostic system, or that the problem is occurring in a completely different system.

Item

Description

Symptom

-

Suspected Area

Indicates the circuit or part which needs to be checked.

See Page

Indicates the page where the flowchart for each circuit is located.

7. CIRCUIT INSPECTION

A description of the main areas of each circuit inspection is below.

Item

Description

Description

The major role, operation of the circuit and its component parts are explained.

DTC No., DTC Detection Condition, Trouble Area

Indicates the diagnostic trouble codes, diagnostic trouble code detection conditions, and trouble areas of a problem.

Wiring Diagram

This shows a wiring diagram of the circuit.

Use this diagram together with ELECTRICAL WIRING DIAGRAM to thoroughly understand the circuit.

Inspection Procedures

Use the inspection procedures to determine if the circuit is normal or abnormal. If abnormal, use the inspection procedures to determine whether the problem is located in the sensors, actuators, wire harnesses or ECU.

Inspection Procedure Connector Illustrations

• Connector being checked is connected:

Connections of tester are indicated by (+) or (-) after the terminal name.

• Connector being checked is disconnected:

For illustrations of inspections between a connector and body ground, information about the body ground is not shown in the illustration.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

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