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Part III Electrical Equipment

Chapter 1 Survey

This part refers to the electrical repair of the Free Cruiser, and analyzes the faults from every system. Then

some practicable diagnosis procedure and repair ways are given.

I. HAND-HELD TESTER

1. Before the tester is used, a through reading of the Tester Operation Manual is commended.

2. Connect the tester to the diagnosis interface with a wire. Turn the ignition switch ON. At this time, if the

tester and ECU control system cannot communicate, the vehicle or the tester may have faults.

(1) Connect the tester lead wire to another vehicle. If the communication is normal, inspect the vehicle

diagnosis Busline or power supply circuit.

(2) If it still cannot communicate when connecting to the other vehicles, it may have faults on tester itself.

Consult the self-inspecting procedure described on the Tester Operation Manual

II. HOW TO PROCEED WITH TROUBLESHOOTING

The basic operation procedure for troubleshooting is as follows.

1. Customer fault analysis

(a) Ask the customer for the conditions and environment when faults happen.

2. Confirm the fault symptoms, and check the DTCs and storage data.

(a) Check the battery positive voltage (Voltage: 10 - 14V when the engine is stopped.)

(b) Inspect the harness, connector and fuse for open and short, etc. by their appearance.

(c) Warm up the engine temperature to the normal operation temperature.

(d) Confirm the fault symptoms and check the DTCs.

(e) Confirm the test procedure for the parts or systems that need checking.

3. Circuit or part inspection

4. Repair

5. Test for checking

(a) After the repair is completed, verify if the fault has been removed.

(If the fault has not appeared yet, a verifying test should be done under the same conditions and environment

when the fault first occurred.)

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III. CUSTOMER FAULT ANALYSIS

NOTES:

1. When the troubleshooting analysis is underway, make sure to confirm the fault symptom correctly. Re-

move kinds of suppositions in order to make an exact judgment. In order to find out what on earth the fault is,

it is extremely important to ask customers about the fault symptoms and the conditions when faults occurred.

2. The 5 items below are the key points to analyze. Those faults that were considered irrelevant and the

repair history, etc are sometimes helpful. Therefore, try your best to collect relevant information, and find out

the relationship between the information you collected and the present information, in order to make refer-

ence in troubleshooting.

Key points of the Customer fault analysis:

1

Vehicle model, system name

2

Date, time, frequency fault occurs

3

 Pavement conditions

4

Running performance, driving and weather conditions

5

Fault symptom

IV. FAULT SYMPTOM AND DTCS

NOTES:

1. The diagnosis system of the Free Cruiser possesses many features. The first important feature is the DTC

Checking. Input a fault from the ECU signal circuit in the form of code, and store it into the ECU memory.

The other feature is Input Signal Inspection. Inspect if the signals from different switches are correctly

inputted into the ECU. These features can quickly narrow the range of troubleshooting, to make an efficient

troubleshooting analysis. In the model of Free Cruiser, the systems below all possess the diagnosis feature.

1

EFI system

2 

ABS system

3

Supplemental Restraint System (SRS)

2. When a DTC is checked, the very important point is: make sure if the fault shown by a DTC still exists, but

is normal now. In addition, when checking the fault symptom, you must check if there is direct relationship

between the fault shown by the DTC and the fault symptom. Therefore, the DTC should be checked before

and after confirming the fault symptom in order to confirm the present conditions. If you do not do so, it is

possible to make some unnecessary troubleshooting analysis on normal systems in some certain circumstances,

thus making it more difficult to locate the fault or repair according to the fault. So, a DTC check should be

done by a normal procedure.

3. The procedure below shows how to make a troubleshooting analysis by checking a DTC and how to make

efficient use of DTC check. Then carefully check the result, make a troubleshooting analysis of the DTC and

a troubleshooting analysis of the symptom.

1

Inspect DTC

2

Record and clear all DTCs

3

Confirm fault symptom

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4

Make a simulation test in a way of symptom simulation

5

Inspect DTC

6

Confirm symptom

V. SYMPTOM SIMULATION

NOTES:

The most difficult conditions to handle in the fault troubleshooting are that the fault symptom dose not appear.

Under the circumstances, make sure first to make a comprehensive analysis to the fault described by the

customer, then to simulate an environment that is similar or the same with the conditions when the fault of the

customer's vehicle occurred. No matter how rich the experience of the technician is and how skillful he is, if

he make a fault troubleshooting analysis without confirm the fault symptom, it is inevitable for him to neglect

some important factors and incorrectly guess, which may cause barriers to repair. For example, if a fault

occurs only when the engine is cool or if a fault occurs only caused by a vibration from pavement and so on,

when the engine is checked in the hot or static state, it is no way to confirm. Because of vibration, high-

temperature or seeping water (Vapor) often causes some faults that are difficult to reappear. So, here are

some effective symptom simulation tests.

KEY POINTS OF SYMPTOM SIMULATION TEST:

In the symptom simulation test, no doubt it is important to confirm the fault symptom, but the fault position or

fault components must be also found out. So, before the test and the pre-inspection of connection, narrow the

range of the circuit where faults may occur according to the fault symptom. Then make a symptom simula-

tion test to see if the circuit measured is normal; the fault symptom is also verified at the same time.

1. Way of Vibration: When vibration may be the major cause of the fault.

For example:

(a) Use your hand to gently vibrate the sensor that is considered the cause of the fault, in order to check if it

is ineffective.

(b) Softly rock the connector and harness in horizontal and vertical direction.

Notes: Hard rock may cause the relay circuit open.

2. Way of Spraying Water: When rainy weather or wet environment may be the major cause of the fault.

(a) Spray water on the vehicle to check if the fault occurs.

NOTES:

Be sure not to directly spray water into the engine compartment. Spray the water on the face of the

radiator to change the temperature and humidity indirectly.

Be sure not to spray water onto electronic devices and controllers.

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3. Way of Heating: When getting warm in the suspected area may be the major cause of the fault.

(a) Use a drier or other similar tool to heat the suspected area to check if the fault occurs.

NOTES:

The heating temperature must be less than 60¡æ £¨140¨H£©(The temperature shall not exceed 

the one that can damage the component.)

Do not directly heat the ECU parts.

4. Another way: When electrical overload may be the major cause of the fault.

 Connect all electrical loads to check if the fault occurs.