Lexus SC300 / Lexus SC400. Service manual — part 86

–MEMO–

–

A304E (1UZ–FE) AUTOMATIC TRANSMISSION

TROUBLESHOOTING

AT–101

WIRING DIAGRAM

AT–66

IN–33

Throttle Position Sensor Circuit

CIRCUIT DESCRIPTION

The throttle position sensor detects the throttle valve opening angle and sends signals to ECM.

DIAGNOSTIC CHART

DIAGNOSTIC CHART

AT–102

–

A304E (1UZ–FE) AUTOMATIC TRANSMISSION

TROUBLESHOOTING

OK

NG

OK

NG

OK

NG

INSPECTION PROCEDURE

1

Main throttle position signal check.

C

OK

Hint

P

Turn ignition switch ON (Do not start the engine).

Check voltage at the terminal T

T

of the DLC2 while grad-

ually depressing the accelerator pedal from the fully
closed position to the fully opened position.

Voltage changes from 0 V to 8 V by stages.

Do not depress the brake pedal during this test. The
voltage will stay at 0 V if depressed.

Proceed to next circuit inspection shown on matrix chart
(See page AT–66).

2

Check throttle position sensor.

See engine troubleshooting section in EG section.

Replace throttle position sensor.

3

Check harness and connector between ECM and throttle position sensor (See page IN–33).

Repair or replace harness or connector.

Check and replace ECM.

–

A304E (1UZ–FE) AUTOMATIC TRANSMISSION

TROUBLESHOOTING

AT–103

AT–66

IN–33

WIRING DIAGRAM

Kick–down Switch Circuit

CIRCUIT DESCRIPTION

The kick–down switch is turned on when the accelerator ped-
al is depressed beyond the full throttle opening and sends sig-
nals to the ECM.
When the kick–down switch is turned on, the ECM controls
gear shifting according to the programmed shift diagrams.
If a short circuit develops in the kick–down switch, the ECM
disregards the kick–down signals and controls shifting at the
normal shift points.

DIAGNOSTIC CHART

DIAGNOSTIC CHART

AT–104

–

A304E (1UZ–FE) AUTOMATIC TRANSMISSION

TROUBLESHOOTING