Lexus ES300 (1997 year). Service manual — part 440

DI0D8–01

I00315

Room Temp.
Sensor

2

1

G–Y

A14

4

5 V

A/C Control Assembly

1

A13

SG

TR

J21

J20

D

E

W–B

W–B

J/C

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–537

689

1997 LEXUS ES300 (RM511U)

CIRCUIT INSPECTION

DTC

11

Room Temperature Sensor Circuit

CIRCUIT DESCRIPTION

This sensor detects the temperature inside the cabin and sends the appropriate signals to the A/C control
assembly.

DTC No.

Detection Item

Trouble Area

11

Open or short in room temperature sensor circuit

Room temperature sensor

Harness or connector between room temp. sensor and A/C

control Assembly

A/C control assembly

WIRING DIAGRAM

BE3840

I00316

I00333

ON

SG(–)

TR(+)

I00317

DI–538

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

690

1997 LEXUS ES300 (RM511U)

INSPECTION PROCEDURE

1

Check voltage between terminals TR and SG of air conditioning control assem-
bly connector

PREPARATION:
(a)

Remove A/C control assembly with connectors still con-
nected (See page

BO–79

).

(b)

Turn the ignition switch ON.

CHECK:
Check voltage between terminals TR and SG of air conditioning
control assembly connector at each temperature.
OK:

at 25

°

C (77

°

F): 1.8 – 2.2 V

at 40

°

C (104

°

F): 1.2 – 1.6 V

NG

Go to step 2.

OK

Proceed to next circuit inspection shown on matrix chart (See page

DI–535

). However, if DTC 11

is displayed, check and replace air conditioning control assembly.

2

Check room temperature sensor.

PREPARATION:
(a)

Remove room temperature sensor from safety pad No.2
(See page

BO–79

).

(b)

Disconnect room temperature sensor connector.

CHECK:
Check resistance between terminals 1 and 2 of room tempera-
ture sensor connector at each temperature.
OK:

at 25

°

(77

°

F): 1.6 – 1.8 k

Ω

at 40

°

(104

°

F): 0.5 – 0.7 k

Ω

HINT:
As the temperature increases, the resistance decreases.

NG

Replace room temperature sensor.

OK

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–539

691

1997 LEXUS ES300 (RM511U)

3

Check harness and connector between air conditioning control assembly and
room temperature sensor (See page

IN–27

).

NG

Repair or replace harness or connector.

OK

Check and replace air conditioning control
assembly.

I00318

A/C Control assembly

5 V

TAM

3

A14

1

A13

SG

Ambient Temp.
Sensor

2

W–R

IM3

10

J21

J20

D

E

J/C

Y

Y

IM3

11

1

W–R

W–R

DI–540

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

692

1997 LEXUS ES300 (RM511U)

DTC

12

Ambient Temperature Sensor Circuit

CIRCUIT DESCRIPTION

This sensor detects the ambient temperature and sends the appropriate signals to the A/C control assembly.

DTC No.

Detection Item

Trouble Area

12

Open or short in ambient temperature sensor circuit

Ambient temperature sensor

Harness or connector between ambient temperature sensor

and A/C control assembly

A/C control assembly

WIRING DIAGRAM

DI0D9–01