Lexus RX300 (MCU15). Manual - part 238

D03336

NC

–

NC

+

Q08218

Magnet

DI–184

–

DIAGNOSTICS

AUTOMATIC TRANSAXLE

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

1

Check resistance between terminals NC

+

 and NC

–

 of Engine & ECT ECU.

PREPARATION:
Disconnect the connector from Engine & ECT ECU.
CHECK:
Check resistance between terminals NC

+

 and NC

–

 of Engine &

ECT ECU.
OK:

Resistance: 620 ± 60 Ω

OK

Check and replace the Engine & ECT ECU (See
page IN–32).

NG

2

Check counter gear speed sensor.

PREPARATION:
Remove the counter gear speed sensor from transaxle.
CHECK:
(a)

Measure resistance between terminals 1 and 2 of speed
sensor.

(b)

Check voltage between terminals 1 and 2 of the speed
sensor when a magnet is put close to the front end of the
speed sensor then taken away quickly.

OK:

(a) Resistance: 620 ± 60 Ω
(b) Voltage is generated intermittently.

HINT:
The voltage generated is extremely low.

NG

Replace the counter gear speed sensor.

OK

Check and repair the harness and connector
between Engine & ECT ECU and counter gear
speed sensor (See page IN–32).

D02290

Line Pressure Con-
trol Pressure

Current Flow to Solenoid

BE4056

ON

OFF

1 cycle

Duty Ratio =

A + B

A

x 100 (%)

D01875

GND

5 V/
Division

1 msec./division

–

DIAGNOSTICS

AUTOMATIC TRANSAXLE

DI–185

LEXUS RX300   (RM785E)

DTC

P1760

Linear Solenoid for Line Pressure Control
Circuit Malfunction (SLT)

CIRCUIT DESCRIPTION

The throttle pressure that is applied to the primary regulator
valve (which modulates line pressure) causes the SLT solenoid
valve, under electronic control, to precisely and minutely modu-
late and generate line pressure according to the accelerator
pedal effort, or engine power output detected.
This reduces the function of line pressure and provides smooth
shifting characteristics.
Upon receiving the throttle valve opening angle signal, Engine
& ECT ECU controls the line pressure by sending a predeter-
mined (*) duty ratio to the solenoid valve, modulating the line
pressure, generating throttle pressure.
(*) Duty Ratio
The duty ratio is the ratio of the period of continuity in one cycle.
For example, if A is the period of continuity in one cycle, and B
is the period of non–continuity, then

DTC No.

DTC Detecting Condition

Trouble Area

P1760

a) or b) condition below are detected 1 seconds or more.

a) SLT

– 

terminal: 0 V

b) SLT

– 

terminal: 12 V

S Open or short in SLT solenoid valve circuit

S SLT solenoid valve

S Engine & ECT ECU

Reference:
Waveform between terminals SLT

+ 

and SLT

–

during engine id-

ling.

DI1O9–17

D01772

SLT Solenoid
Valve

Automatic Transaxle

E1

2

E1

7

E6

3

E6

2

G–B

G

SLT

+

SLT–

Engine & ECT ECU

O

G

DI–186

–

DIAGNOSTICS

AUTOMATIC TRANSAXLE

LEXUS RX300   (RM785E)

WIRING DIAGRAM

D03445
D03446
D02968

D03729

2

1

2

1

When battery voltage is applied.

When battery voltage is cut off.

Valve moves in

direction

in illustration at left.

Valve moves in

direction

in illustration at left.

–

DIAGNOSTICS

AUTOMATIC TRANSAXLE

DI–187

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

1

Check SLT solenoid valve.

PREPARATION:
(a)

Jack up the vehicle.

(b)

Remove the oil pan.

(c)

Disconnect the solenoid connector.

CHECK:
Check the solenoid resistance.

Measure resistance between terminals 1 and 2 of sole-
noid connector.

OK:

Resistance: 5.0 – 5.6 Ω

CHECK:
Check the solenoid operation.

Connect positive (+) lead with an 8 – 10W bulb to terminal
1 of solenoid connector and negative (–) lead to terminal
2, then check the movement of the valve.

OK:

NG

Replace SLT solenoid valve.

OK

2

Check harness and connector between SLT solenoid valve and Engine & ECT
ECU (See page IN–32).

NG

Repair or replace harness or connector.

OK

Replace Engine & ECT ECU (See page 
IN–32).