Lexus RX300 (MCU15). Service manual - part 401

I18280

1

Hot

Cool

3

5

LHD model:

RHD model:

Cool

Hot

Hot

DI–834

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

LEXUS RX300   (RM785E)

3

Check air mix damper position sensor.

PREPARATION:
(a)

Remove heater unit (See page AC–27).

(b)

Disconnect air mix damper control servomotor assembly
connector.

CHECK:
Measure resistance between terminals 1 and 3 of air mix damp-
er control servomotor assembly connector.
OK:

Resistance : 4.2 – 7.8 kΩ

CHECK:
While operating air mix damper control servomotor, following
the procedure on page DI–841, measure resistance between
terminals 1 and 5 of air mix damper control servomotor assem-
bly connector.
OK:

Position

Resistance

Max. cool

3.6 – 6.8 kΩ

Max. hot

0.5 – 1.1 kΩ

HINT:
As the air mix damper control servomotor moves from cool side
to hot side, the resistance decreases.

NG

Replace air mix damper control servomotor as-
sembly.

OK

4

Check harness and connector between A/C ECU (Combination meter ECU) and
air mix 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).

(V)

4

1

0

100 %

TPI

 terminal voltage

Damper opening angle

I08370

A24 Air Inlet Damper Position Sensor
(Air Inlet Control Servomotor)

1

5

3

V–W

GR

B–W

8

11

S5–2

TPI

SG–2

A/C ECU
(Combination meter ECU)

C11

1

C11

C11

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–835

LEXUS RX300   (RM785E)

DTC

B1432/32 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 ECU (Combination
meter ECU).
The position sensor is built into the air inlet damper control ser-
vomotor assembly.

DTC No.

Detection Item

Trouble Area

B1432/32

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

S Air inlet damper position sensor.

S Harness or connector between air inlet damper control servo-

B1432/32

Short to ground or  ower source circuit in air inlet dam er  osi

tion sensor circuit.

Harness or connector between air inlet dam er control servo

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

S A/C ECU (Combination meter ECU).

WIRING DIAGRAM

DI3G1–02

I08354

SG–2

(+)

(–)

TPI

DI–836

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

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 inlet damper position using hand–held tester.

PREPARATION:
Connect the hand–held tester to the DLC3.
CHECK:
Check the current position of air inlet damper and the target position of air inlet 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 TPI and SG–2 of A/C ECU (Combination meter
ECU) connector.

PREPARATION:
Remove A/C ECU with connectors still connected.
CHECK:
(a)

Turn ignition switch ON.

(b)

Press REC/FRS switch to change air inlet between fresh
and recirculation air, and measure voltage between termi-
nals TPI and SG–2 of A/C ECU when the air inlet damper
control servomotor operates.

OK:

FRS–REC Switch

Voltage

REC

3.5 – 4.5 V

FRS

0.5 – 1.5 V

HINT:
As the air inlet damper control servomotor is moved form REC
side to FRS side, the voltage decreases.

NG

Go to step 3.

OK

Proceed to next circuit inspection shown on problem symptoms table (See page DI–812).  Howev-
er, if DTC B1432/32 is displayed, check and replace A/C ECU (Combination meter ECU).

I18281

1

3

5

LHD model:

RHD model:

FRS

REC

FRS

REC

–

DIAGNOSTICS

AIR CONDITIONING SYSTEM

DI–837

LEXUS RX300   (RM785E)

3

Check air inlet damper position sensor.

PREPARATION:
(a)

Remove blower unit unit (See page AC–36).

(b)

Disconnect air inlet damper control servomotor assembly
connector.

CHECK:
Measure resistance between terminals 1 and 3 of air inlet
damper control servomotor assembly connector.
OK:

Resistance : 4.2 – 7.8 kΩ

CHECK:
While operating air inlet damper control servomotor, following
the procedure on page DI–844, measure resistance between
terminals 1 and 5 of air inlet damper control servomotor assem-
bly connector.
OK:

Resistance

Damper Position

Resistance

REC side

3.1 – 5.8 kΩ

FRS side

0.8 – 1.6 kΩ

HINT:
As the air inlet damper control servomotor moves from REC
side to FRS side, the resistance decreases.

NG

Replace air inlet damper control servomotor as-
sembly.

OK

4

Check harness and connectors between A/C ECU (Combination meter ECU) and
air inlet 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).