Lexus ES300 (1997 year). Manual - part 445

0

100%

Damper opening angle

(V)

T

P

I terminal voltage

4

1

I00328

Air Mix Damper
Position Sensor
(Air Mix Control 
Servomotor)

4

3

5

B–Y

W–R

W–R

8

11

A/C Control Assembly

S5

TP

SG

To Solar Sensor

J/C

J18

J18

J19

A13

A14

A13

J20

J20

D

E

C

A

C

5 V

5 V

1

L

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–557

709

1997 LEXUS ES300   (RM511U)

DTC

31, 41

Air Mix Damper Position Sensor Circuit

CIRCUIT DESCRIPTION

This sensor detects the position of the air mix damper and
sends the appropriate signals to the A/C control assembly. The
position sensor is built into the air mix control servomotor.

DTC No.

Detection Item

Trouble Area

31

Short to ground or power source circuit in air mix damper posi-

tion sensor circuit.

Air mix damper position sensor

Harness of connector between air mix control servomotor and

41

Air mix damper position sensor value does not change even if

ECM operates air mix control servomotor.

Harness of connector between air mix control servomotor and

A/C control assembly

A/C control assembly

WIRING DIAGRAM

DI0DF–01

BE3840

I00329

I00337

ON

SG(–)

TP(+)

DI–558

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

710

1997 LEXUS ES300   (RM511U)

INSPECTION PROCEDURE

1

Check voltage between terminals TP and SG of A/C control assembly connector.

PREPARATION:
(a)

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

BO–79

).

(b)

Turn ignition switch ON.

CHECK:
Change the set temperature to activate the air mix damper, and
measure the voltage between terminals TP and SG of A/C con-
trol assembly connector each time when the set temperature is
changed.
OK:

Set Temperature

Voltage

Max. cool

3.5 – 4.5 V

Max. hot

0.5 – 1.8 V

HINT:
As the set temperature increases, the voltage decreases grad-
ually without interruption.

NG

Go to step 2.

OK

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

DI–535

). However, if DTC 31

or 41 is displayed, check and replace A/C control assembly.

I00364

1

5
4

3
2

Max. HOT

Max. COOL

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–559

711

1997 LEXUS ES300   (RM511U)

2

Check air mix damper position sensor.

PREPARATION:
(a)

Remove air mix control servomotor (See page 

AC–73

).

(b)

Disconnect air mix control servomotor connector.

CHECK:
Measure resistance between terminals 4 and 5 of air mix control
servomotor connector.
OK:

Resistance: 4.8 – 7.2 k

Ω

CHECK:
While operating  air mix control servomotor as shown in the pro-
cedure on page 

DI–563

, measure resistance between termi-

nals 3 and 5 of air mix control servomotor connector.
OK:

Position

Resistance

Max. cool

3.8 – 5.8 k

Ω

Max. hot

0.95 – 1.45 k

Ω

HINT:
As the air mix control servomotor moves from cool side to hot
side, the resistance decreases gradually without interruption.

NG

Replace air mix control servomotor.

OK

3

Check harness and connector between A/C control assembly and air mix control
servomotor (See page 

IN–27

).

NG

Repair or replace harness or connector.

OK

Check and replace A/C control assembly.

0

100%

Damper opening angle

0.9 V

4.1 V

(V)

T

P

I terminal voltage

4

1

I00330

A/C Control Assembly

5 V

5 V

SG

TPI

S5

A13

11

7

A14

1

A13

J19

J19

J18

A

C

A

L

L

P–L

W–R

W–R

J20

J20

E

E

J/C

3

5

1

Air Inlet Damper
Position Sensor
(Air Inlet Control 
 Servomotor)

To Solar Sensor

DI–560

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

712

1997 LEXUS ES300   (RM511U)

DTC

32, 42

Air Inlet Damper Position Sensor Circuit

CIRCUIT DESCRIPTION

This sensor detects the position of the air inlet damper and
sends the appropriate signals to the A/C control assembly. The
position sensor is built into the air inlet control servomotor.

DTC No.

Detection Item

Trouble Area

32

Short to ground or power source circuit in air inlet damper posi-

tion sensor circuit.

Air inlet damper position sensor.

Harness or connector between air inlet control servomotor

42

Air inlet damper position sensor value does not change even if

A/C control assembly operates air inlet control servomotor.

Harness or connector between air inlet control servomotor

and A/C control assembly.

A/C control assembly.

WIRING DIAGRAM

DI0DG–01