Lexus SC300 / Lexus SC400. Service manual - part 192

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BODY ELECTRICAL SYSTEM

Wireless Door Lock Control System

BE–441

HOW TO PROCEED WITH TROUBLESHOOTING

HINT: Troubleshooting of the wireless door lock control system is based on the premise that the door lock control
system is operating normally. Accordingly, before troubleshooting the wireless door lock control system, first
make certain that the door lock control system is operating normally.
Perform troubleshooting in accordance with the procedure on the following page.

CUSTOMER PROBLEM ANALYSIS

Using the customer problem analysis check sheet of reference, ask the customer in as much detail as pos-
sible about the problem.

PROBLEM

SYMPTOM

CONFIRMATION,

SYMPTOM SIMULATION

Confirm the problem symptoms. If the problem does not reappear, be sure to simulate the problem using
the “Problem Simulation Method”.
At this stage check whether the whole wireless door lock control system fails to operate, or whether only
some of the particular functions fail to operate.

PRECHECK TYPE I,

PRECHECK TYPE II

Using the self diagnosis function of the wireless door lock ECU, perform Precheck Type I to find out if the
system is normal (system non–operation due to external noise, etc.) or if the abnormality lies with the ve-
hicle. In Precheck Type II, locate if the cause of problem lies in the transmitter, the antenna or the vehicle.
Perform Precheck Type I when whole wireless door lock control system fails to operate only at a specific
locality.
Perform Precheck Type II when whole wireless door lock control system fails to operate no matter where
the locality is.
When only some functions of wireless door lock control system do not operate, proceed to [8] on the Matrix
Chart of Problem Symptoms.

INSPECTION OF TRANSMITTER, [7] INSPECTION OF ANTENNA CIRCUIT

If it is found in Precheck Type II that the cause of the problem is in the transmitter or antenna, proceed to
the appropriate pages and start troubleshooting.

MATRIX CHART OF PROBLEM SYMPTOMS

Confirm the order of inspection for each applicable problem symptom on the matrix chart.

CIRCUIT

INSPECTION

Proceed with diagnosis of each circuit in accordance with the inspection order confirmed in [8]. Judge
whether the cause of the problem is in the sensor, wire harness and connectors, or the ECU.

[10] REPAIR

If the cause of the problem is found in [9]., perform repairs.

[11] CONFIRMATION TEST

After completing repairs, confirm that the problem is eliminated and that all functions of the wireless door
lock control system are normal.

BE–442

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BODY ELECTRICAL SYSTEM

Wireless Door Lock Control System

Vehicle Brought to Workshop

Customer Problem Analysis

BE–444

Problem Symptom Confirmation

Matrix Chart of Problem Symptoms

Circuit Inspection

Identification of Problem

Repair

Confirmation Test

END

Whole wireless door lock
Control system does not operate

Problem occurs
everywhere

Items inside are titles of pages
in this manual, with the page number
indicated in the bottom portion.
See the indicated pages for detailed
explanations.

Symptom Simulation

Precheck Type I

BE–445

Precheck Type II

BE–446

System is
Normal

Inspection of
Transmitter

BE–449

Inspection of
Atenna Circuit

BE–448

Transmitter Malfunction

Problem occurs
only at a
specific locality

Some functions of wireless door
lock control system do not operate

Malfunction on
vehicle side

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BODY ELECTRICAL SYSTEM

Wireless Door Lock Control System

BE–443

CUSTOMER PROBLEM ANALYSIS CHECK SHEET

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WIRELESS DOOR LOCK CONTROL System Check Sheet

Inspector’s

Name:

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Registration No.

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Customer’s Name

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Registration Year

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Frame No.

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Date Vehicle
Brought In

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Odometer Reading

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Miles

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Date of Problem Occurrence

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Frequency of Problem Occurrence

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Constant

Sometimes (

times/per

day, month)

Once Only

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Conditions at

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Weather

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Fine

Cloudy

Rainy

Snowy

Various/Others

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Conditions at
Time of Problem
Occurrence

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Outdoor Temperature

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Hot

Warm

Cool

Cold (Approx.

C))

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Place

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Everywhere

Specific Locality (

)

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Date Transmitter Battery Last Replaced

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Whole wireless door lock control system does not operate

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Whole wireless door lock control system does not operate.

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Only door unlock operation is not possible.

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Only door lock operation is not possible.

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Only key confine prevention function is not possible.

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Wireless door lock function operates even when each door is opened.

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Wireless door lock function incorrectly.

(Although one door is unlocked, when the transmitter
switch is pressed, all doors unlock.)

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When RH door is unlocked.

When LH door is unlocked.

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Others

Problem Symptom

BE–444

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BODY ELECTRICAL SYSTEM

Wireless Door Lock Control System

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