Lexus IS250 · Service Manual HEATER & AIR CONDITIONING SYSTEM

B1443/43

Diagnostic trouble codes

DESCRIPTION

The mode damper servo sends pulse signals to inform the air conditioner amplifier of the damper position. The air conditioner amplifier activates the motor (normal, reverse) based on the signals to move the mode damper to any position, which controls the air outlet switching.

HINT:
Confirm that no mechanical problem is present because this diagnostic code can be output when either a damper link or damper is mechanically locked.

DTC No.
DTC Detection Condition
Trouble Area
B1443/43
Air outlet damper position sensor value does not change even if air conditioner amplifier operates air outlet control servo motor
  1. Air outlet control servo motor
  2. Air conditioning harness
  3. A/C amplifier

WIRING DIAGRAM

E116879E03

INSPECTION PROCEDURE


1. READ VALUE OF INTELLIGENT TESTER
  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG) and turn the intelligent tester main switch on.

  1. Operate the MODE switch.

  1. Select the item below in the Data List, and read the display on the intelligent tester.

Data List / Air Conditioner: 
Item
Measurement Item / Display (Range)
Normal Condition
Diagnostic Note
Air Outlet Servo Pulse (D)
(Air Out Pulse-D)
Driver side air outlet servo motor target pulse / Min.: 0, Max.: 255
FACE: 9 to 17 (pulse)
B/L: 32 to 38 (pulse)
FOOT: 56 to 70 (pulse)
FOOT/DEF: 84 (pulse)
DEF: 97 (pulse)
-

OK:
The display is as specified in the normal condition column.


Result:
Result
Proceed to
NG
A
OK (When troubleshooting according to the PROBLEM SYMPTOMS TABLE)
B
OK (When troubleshooting according to the DTC)
C



B
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

C
REPLACE AIR CONDITIONING AMPLIFIER
A


2. REPLACE AIR OUTLET CONTROL SERVO MOTOR

HINT:
Since the servo motor cannot be inspected while it is removed from the vehicle, replace the servo motor with a normal one and check that the condition returns to normal.

  1. Check for DTCs.

    Result:
    Result
    Proceed to
    DTC B1443/43 is output
    A
    DTC B1443/43 is not output
    B



B
END
A

REPLACE AIR CONDITIONING HARNESS


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