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Home >> Lexus >> 2004 >> IS 300 Base, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 249 (Air Conditioning System (Diagnosis)) >> Circuit Inspection >> DTC B1411 Room Temperature Sensor Circuit >> Inspection Procedure

Inspection Procedure

WARNING: This page is about a different car, the 2003 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.

HINT:

In case of using the LEXUS hand-held tester, start the inspection step 1 and in case of not using the LEXUS hand-held tester, start from step  2.

  1. Check room temp. sensor using LEXUS hand-held tester. 

    PREPARATION: 

    Connect the LEXUS hand-held tester to the DLC3.

    CHECK: 

    Check the room temp. sensor using DATA LIST.

    1. OK: Check and replace A/C amplifier. 
    2. NG: Go to next step. 
  2. Check voltage between terminals TR and SG of A/C amplifier connector. 

    PREPARATION: 

    Remove A/C amplifier with connectors still connected.

    CHECK: 

    1. Turn ignition switch to ON.
    2. Measure voltage between terminals TR and SG of A/C amplifier connector at each temperature.

    OK: 

    Voltage: 

    at 25°C (77°F):1.8 - 2.2 V 

    at 40°C (104°F):1.2 - 1.6 V 

    Fig 1: Measuring Voltage Between Terminals TR And SG Of A/C Amplifier Connector
    G03379767Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    HINT:

    As the temperature increases, the voltage decreases.

    1. NG: Go to step 3. 
    2. OK: Proceed to next circuit inspection shown on problem symptoms table (See  PROBLEM SYMPTOMS TABLE  ). However, if DTC B1411 is displayed, check and replace A/C amplifier. 
  3. Check room temperature sensor. 

    PREPARATION: 

    Remove room temperature sensor (See ROOM TEMPERATURE SENSOR ).

    CHECK: 

    Measure resistance between terminals 1 and 2 of room temperature sensor connector at each temperature.

    OK: 

    Resistance: 

    at 25°C (77°F): 1.65 - 1.75 kΩ 

    at 50°C (122°F): 0.55 - 0.65 kΩ 

    Fig 2: Measuring Resistance Between Terminals 1 And 2 Of Room Temperature Sensor Connector
    G03379768Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    HINT:

    As the temperature increases, the resistance decreases.

    1. NG: Replace room temperature sensor. 
    2. OK: Go to next step. 
  4. Check harness and connector between A/C amplifier and room temperature sensor (INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits)). 
    1. NG: Repair or replace harness or connector. 
    2. OK: Check and replace A/C amplifier. 
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