Lexus RX300 (MCU15). Service manual - part 402

TPM

 terminal 

voltage

(V)

4

1

0

100 %

Damper opening angle

I08342

S5–1

TPO

SG–1

C10

3

4

10

G–R

LG–R

B–R

IF1

3

2

6

3

5

1

A26 
Air Outlet Damper Position Sensor
(Air Outlet Control Servomotor)

A/C ECU (Combina-
tion Meter ECU)

G–B

LG–R

B–Y

IF1

IF1

C10

C10

DI–838

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

LEXUS RX300   (RM785E)

DTC

B1433/33 Air Outlet 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 ECU (Combination
meter ECU).
The position sensor is built into the air outlet damper control ser-
vomotor assembly.

DTC No.

Detection Item

Trouble Area

B1433/33

Short to ground or power source circuit in air outlet damper

S Air outlet damper position sensor.

S Harness or connector between air outlet damper control ser-

B1433/33

Short to ground or  ower source circuit in air outlet dam er

position sensor circuit.

Harness or connector between air outlet dam er control ser

vomotor assembly and A/C ECU (Combination meter ECU).

S A/C ECU (Combination meter ECU).

WIRING DIAGRAM

DI3G2–02

I08356

TPO

SG–1

(–)

(+)

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–839

LEXUS RX300   (RM785E)

INSPECTION PROCEDURE

HINT:
In case of using the hand–held tester, start the inspection from step1 and in case of not using the hand–held
tester, start from step2.

1

Check air outlet damper position using hand–held tester.

PREPARATION:
Connect the hand–held tester to the DLC3.
CHECK:
Check the current position of air outlet damper and the target position of air outlet damper.
OK:

The current position and target position are almost similar.

OK

Check and replace A/C ECU (Combination me-
ter ECU).

NG

2

Check voltage between terminals TPO and SG–1 of A/C ECU (Combination meter
ECU) connector.

PREPARATION:
(a)

Remove A/C ECU with connectors still connected.

(b)

Turn ignition switch ON.

CHECK:
Measure the voltage between terminals TPO and SG–1 of A/C
ECU.
OK:

Air outlet position

Voltage

FACE

3.5 – 4.5 V

DEF

0.5 – 1.5 V

HINT:
As the air outlet damper control servomotor is moved from
VENT side to DEF side, the voltage decreases gradually with-
out interruption.

NG

Go to step 3.

OK

Proceed to next circuit inspection shown on problem symptoms table (See page DI–812).  Howev-
er, if DTC B1433/33 is displayed, check and replace A/C ECU (Combination meter ECU).

I18282

1

5

3

FACE

DEF

LHD model:

RHD model:

FACE

DEF

DI–840

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

LEXUS RX300   (RM785E)

3

Check air outlet damper position sensor.

PREPARATION:
(a)

Remove A/C unit (See page AC–63).

(b)

Disconnect air outlet damper control servomotor assem-
bly connector.

CHECK:
Measure resistance between terminals 1 and 3 of air outlet ser-
vomotor assembly connector.
OK:

Resistance : 4.2 – 7.8 kΩ

CHECK:
While operating air outlet damper control servomotor as in the
procedure on page DI–847, measure resistance between ter-
minals 1 and 3 of air outlet damper control servomotor.
OK:

Resistance:

Damper Position

Resistance

DEF

0.5 – 1.1 kΩ

FACE

3.6 – 6.8 kΩ

HINT:
As the air outlet servomotor moves from DEF side to FACE side,
the resistance decreases gradually without interruption.

NG

Replace air outlet damper control servomotor.

OK

4

Check harness and connector between A/C ECU (Combination meter ECU) and
air outlet damper control servomotor assembly (See page IN–32).

NG

Repair or replace harness or connector.

OK

Check and replace A/C ECU (Combination
meter ECU).

I08346

A/C ECU (Combina-
tion meter ECU)

A25 
Air Mix Damper
Servomotor

7

7

6

C10

IF1

8

Y

Y–R

8

9

AMH

AMC

C10

IF1

Y–G

Y–B

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–841

LEXUS RX300   (RM785E)

DTC

B1441/41 Air Mix Damper Control Servomotor Circuit

CIRCUIT DESCRIPTION

The air mix damper control servomotor is controlled by the A/C ECU (Combination meter ECU) and moves
the air mix damper to the desired position.

DTC No.

Detection Item

Trouble Area

B1441/41

Air mix damper position sensor value does not change even if

A/C ECU (Combination meter ECU) operates air mix damper

control servomotor.

S Air mix damper control servomotor.

S Air mix damper position sensor.

S Harness or connector between A/M damper control servomo-

tor and A/C ECU (Combination meter ECU)

S Harness or connector between A/M damper position sensor

and A/C ECU (Combination meter ECU)

S A/C ECU (Combination meter ECU).

WIRING DIAGRAM

DI3G3–03