Lexus SC300 / Lexus SC400. Service manual — part 71

ECM DATA MONITOR BY USING LEXUS
HAND–HELD TESTER

AT0RE–01

1.

Hook up the LEXUS hand–held tester to the DLC2.

2.

Monitor the ECM data by following the prompts on the
tester screen.
HINT: LEXUS hand–held tester has a “Snapshot” function
which records the monitored data.
Please refer to the LEXUS hand–held tester operator’s
manual for further details.

ECM TERMINAL VALUES
MEASUREMENT BY USING LEXUS
BRAKE–OUT BOX AND LEXUS
HAND–HELD TESTER

AT0RF–01

1. Hook up the LEXUS brake–out box and LEXUS

hand–held tester to the vehicle.

2. Read the ECM input/output values by following the

prompts on the tester screen.
HINT: LEXUS hand–held tester has a “Snapshot” function.
This records the measured values and is effective in the diag-
nosis of intermittent problems.
Please refer to the LEXUS hand–held tester/LEXUS brake–
out box operator’s manual for further details.

AT–40

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A304E (1UZ–FE) AUTOMATIC TRANSMISSION

TROUBLESHOOTING

PROBLEM SYMPTOM CONFIRMATION

AT09U–07

Taking into consideration the results of the customer problem analysis, try to reproduce the symptoms of
the trouble. If the problem is that the transmission does not up–shift, does not down–shift, or the shift point
is too high or too low, conduct the following road test referring to the automatic shift schedule and simulate
the problem symptoms.

ROAD TEST

AT09V–05

NOTICE: Perform the test at normal ATF operating temperature

50–80

°

C (122–176

°

F).

1.

D POSITION TEST (NORM AND PWR PATTERN)
Shift into the D position and fully depress the accelerator ped-
al and check the following points:

(a) Check up–shift operation

1

→

2, 2

→

3 and 3

→

O/D up–shift takes place, and shift point

should conform to those shown in the automatic shift sched-
ule (See page AT–45)
Conduct a test under both Normal and Power patterns.
HINT:

•

O/D up–shift or lock–up will not occur when the engine
coolant temp. is below 60

C (140

F) and speed is under

60 km/h (37 mph), or if there is a 10 km/h (6 mph)
difference between the set cruise control speed.

•

3rd up–shift or lock–up will not occur when engine
coolant temp. is below 35

C (95

F) and speed is under

40 km/h (25 mph).

(b) Check for shift shock and slip.

In the same manner, check the shock and slip at the 1

→

2,

2

→

3 and 3

→

O/D up–shifts.

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A304E (1UZ–FE) AUTOMATIC TRANSMISSION

TROUBLESHOOTING

AT–41

(c) Check for abnormal noise and vibration.

Run at the D position lock–up or O/D gear and check for ab-
normal noise and vibration.
HINT: The check for the cause of abnormal noise and vibra-
tion must be performed very thoroughly care as it could also
be due to loss of balance in the propeller shaft, differential,
torque converter clutch, etc..

(d) Check kick–down operation

While running in the D position, 2nd, 3rd and O/D gears,
check to see that the possible kick–down vehicle speed limits
for 2

→

1, 3

→

2 and O/D

→

3 kick–downs conform to those indi-

cated on the automatic shift schedule. (See page AT–45)

(e) Check abnormal shock and slip at kick–down.

(f) Check the lock–up mechanism.

(1) Drive in D position, O/D gear, at a steady speed (lock–up

ON) of about 58 km/h (36 mph).

(2) Lightly depress the accelerator pedal and check that the

engine RPM does not change abruptly.

If there is a big jump in engine RPM, there is no lock–up.

2.

2 POSITION TEST
Shift into the 2 position and fully depress the accelerator ped-
al and check the following points:

(a) Check up–shift operation

Check to see that the 1

→

2 up–shift takes place and that the

shift point conforms to that shown on the automatic shift
schedule. (See page AT–45)
HINT:

•

There is no O/D up–shift and lock–up in the 2 position.

(b) Check engine braking

While running in the 2 position and 2nd gear, release the ac-
celerator pedal and check the engine braking effect.

AT–42

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A304E (1UZ–FE) AUTOMATIC TRANSMISSION

TROUBLESHOOTING

(c) Check for abnormal noise during acceleration and

deceleration, and for shock at up–shift and down–shift.

3.

L POSITION TEST
Shift into the 2 position and fully depress the accelerator ped-
al and check the following points:

(a) Check no up–shift

While running in the L position, check to see that there is no
up–shift to 2nd gear.

(b) Check engine braking

While running in the L position, release the accelerator pedal
and check the engine braking effect.

(c) Check for abnormal noise during acceleration and

deceleration.

4. R

POSITION

TEST

Shift

into the R position and fully depress the accelerator ped-

al and check for slipping.

CAUTION: Before conducting this test ensure that the test area

is free from personnel and obstructor.

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A304E (1UZ–FE) AUTOMATIC TRANSMISSION

TROUBLESHOOTING

AT–43