Lexus SC300 / Lexus SC400. Manual - part 27

Diag. Code 33, 34  Air Outlet Damper Position Sensor Circuit

CIRCUIT DESCRIPTION

This sensor detects the position of the air outlet
damper and sends the appropriate signals to the
air conditioner control assembly.
The position sensor is built into the air outlet ser-
vomotor assembly.

Code No.

Diag. Code Detecting Condition

Trouble area

33

Short to ground or power source circuit in air
outlet damper position sensor circuit.

Air outlet damper position sensor.

Harness or connector between air outlet
servomotor assembly and A/C control as-

43

Air outlet damper position sensor value does
not change even if A/C control assembly 
operates air outlet servomotor.

servomotor assembly and A/C control   as-
sembly

 A/C control assembly

DIAGNOSTIC CHART

Check voltage between terminals TPM and

SG  of  air conditioner control assembly 

connector.

Check air outlet damper position sensor.

Check harness and connector between air

conditioner control assembly and air outlet
servomotor assembly (See page 

IN–27

).

Check and replace air conditioner control 

assembly.

Proceed to next circuit inspection

shown on matrix chart (See page

AC-36

). However, when Diag.

code 33 or 43 is displayed, check
and replace air conditioner control

assembly.

Replace air outlet servomotor
assembly.

Repair or replace harness or

connector.

AC–66

–

AIR CONDITIONING SYSTEM

Troubleshooting

Check  voltage between terminals TPM and SG of air conditioner control
assembly connector.

(1)

Remove console upper panel.(See page 

BO-111

).

(2)

Remove A/C control assembly with 
connectors still connected.

(3)

Turn ignition switch ON.

In addition, as the air outlet servomotor is moved
from REC side to FRS side, the voltage decreases
gradually without  interruption.

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

AC-36

).However, when Diag. code 32 or 42 is dis-

played, check and replace air conditioner control assembly.

Check air outlet damper position sensor.

(1)

Remove heater unit. (See page 

AC-127

)

(2)

Disconnect air outlet servomotor assembly
connector.

Measure resistance between terminals S5 and SG of
air  outlet servomotor assembly connector.

Resistance:       4.7~7.2  k

While operating air outlet servomotor as in the
procedure on page 

AC-69

, measure  resistance

between terminals TP1 and SG of air outlet servo-
motor assembly connector.

Resistance:

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

Replace  air outlet servomotor assembly.

Check for open and short in harness and connector between air conditioner
control assembly and air outlet servomotor assembly (See page 

IN-27

).

Repair or replace harness or connector.

Check and replace air conditioner control assembly.

INSPECTION PROCEDURE

–

AIR CONDITIONING SYSTEM

Troubleshooting

AC–67

Diag. Code 43

Air Outlet Servomotor Circuit

CIRCUIT DESCRIPTION

Code No.

Diag. Code Detecting Condition

Trouble area

43

Air outlet damper position sensor value does not
change even if A/C control assembly operated air
outlet servomotor.

Air outlet servomotor.

Air outlet damper position sensor.

Harness or connector between A/C control
assembly air outlet servomotor, air outlet
damper position sensor.

A/C control assembly

DIAGNOSTIC CHART

Actuator check.

Check air outlet servomotor.

Check harness and connector between air

conditioner control assembly and air outlet

servomotor, air outlet servomotor and bat-

tery, air outlet servomotor and body ground.
(See page 

IN-27

).

Check and replace air conditioner control 

assembly.

Proceed to next circuit inspection

show on matrix chart (See page

AC-36

).

Replace air outlet servomotor .

Repair or replace harness or

connector.

AC–68

–

AIR CONDITIONING SYSTEM

Troubleshooting

Actuator check.

(1)

Set to the actuator check mode

(See page 

AC-30

).

(2)

Press the FRS           switch and change it to
step operation.

Press FRS                switch and check the
condition of the flow.

The mode changes with the change in the tem-
perature display as shown in the table.

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

AC-36

).

Connect positive 

 lead to terminal 4 and negative



 lead to terminal 5.

The lever turns smoothly to FACE position.

Remove heater unit.(See page 

AC-125

).

Connect negative 



 lead to terminal 4 and positive 

lead to terminal 5.

The lever moves smoothly to DEF position.

Check air outlet servomotor.

Replace  air outlet servomotor.

Check for open and short in harness and connector between air conditioner control 

assembly and outlet servomotor, outlet servomotor and battery, outlet servomotor and
body ground.(See page 

IN-27

).

Repair or replace harness or connector.

Check and replace air conditioner control
 assembly.

INSPECTION PROCEDURE

–

AIR CONDITIONING SYSTEM

Troubleshooting

AC–69