Lexus IS250 · Service Manual HEATER & AIR CONDITIONING SYSTEM

B1442/42

Diagnostic trouble codes

DESCRIPTION

The damper servo (air inlet control) 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 air inlet mode selection air inlet control damper to any position, which controls the intake air settings (FRESH, FRESH / RECIRCULATION, and RECIRCULATION).

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
B1442/42
Air inlet damper position sensor value does not change even if air conditioner amplifier operates air inlet control servo motor
  1. Air inlet control servo motor
  2. Air conditioning harness
  3. A/C amplifier

WIRING DIAGRAM

E116879E02

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 R/F (Recirculation/Fresh) 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 Inlet Damper Targ Pulse
(A/I Damp Targ Pls)
Air inlet damper target pulse / Min.: 0, Max.: 255
LHD:
RECIRCULATION: 31 (pulse)
FRESH: 7 (pulse)
RHD:
RECIRCULATION: 7
FRESH: 27
-

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 INLET 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 B1442/42 is output
    A
    DTC B1442/42 is not output
    B



B
END
A

REPLACE AIR CONDITIONING HARNESS


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