AIR CONDITIONING SYSTEM, Diagnostic DTC:B1479/79

DTC Code DTC Name
B1479/79 Flow Sensor Circuit

DESCRIPTION

The A/C mass flow sensor, which is mounted on the A/C compressor, is used to detect the amount of refrigerant flow. The A/C mass flow sensor converts the amount of refrigerant flow that is detected to a voltage value to send it to the A/C amplifier. The voltage value sent from the A/C mass flow sensor changes depending on the amount of refrigerant flow. As the amount of refrigerant flow becomes larger, the voltage becomes lower. As the amount of refrigerant flow becomes smaller, the voltage becomes higher. The A/C amplifier supplies 5 V to the A/C mass flow sensor and monitors change in the voltage value sent from the A/C mass flow sensor. The A/C amplifier then sends a signal to the ECM via CAN communication to allow the ECM to control the engine speed while the air conditioning is on.

DTC No. DTC Detection Condition Trouble Area
B1479/79 Open or short in A/C mass flow sensor circuit

  • A/C compressor (A/C mass flow sensor)

  • Harness or connector between A/C compressor (A/C mass flow sensor) and A/C amplifier

  • A/C amplifier

WIRING DIAGRAM

A019LKRE12

INSPECTION PROCEDURE

PROCEDURE


  1. READ VALUE USING INTELLIGENT TESTER


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the intelligent tester on.

    4. Enter the following menus: Body / Air Conditioner / Data List.

    5. Check the value(s) by referring to the table below.

      Air Conditioner
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Flow Sensor

      A/C mass flow sensor /

      Min.: 0.00 V

      Max.: 5.00 V

      A/C on, Blower switch HI: 0.70 to 3.80 V

      A/C off, Blower switch off: 3.80 to 4.20 V

      		 A/C mass flow sensor is malfunctioning when a constant value between 0.70 and 4.20 V is displayed continuously for more than 4 seconds.
      OK
      The display is as specified in the Normal Condition column.
      Result
      Result Proceed to
      OK (When troubleshooting according to Problem Symptoms Table) A
      OK (When troubleshooting according to the DTC) B
      NG (When a constant value between 0.7 and 4.2 V is displayed continuously for more than 4 seconds) C

    B

    REPLACE A/C AMPLIFIER Click here

    C

    REPLACE A/C COMPRESSOR (A/C MASS FLOW SENSOR) Click here

    A

  2. READ VALUE USING INTELLIGENT TESTER


    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the intelligent tester on.

    4. Enter the following menus: Body / Air Conditioner / Data List.

    5. Check the value(s) by referring to the table below.

      Air Conditioner
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      A/C Cutoff Signal

      A/C control cutoff signal /

      OFF or ON

      A/C switch on: OFF

      A/C switch off: ON

      		 -
      Result
      Result Proceed to
      Value in Data List indicates OFF A
      Value in Data List indicates ON B

    B

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    A

  3. REPLACE A/C COMPRESSOR (A/C MASS FLOW SENSOR)


    1. Replace the A/C compressor (A/C mass flow sensor).


      Tech Tips

      Since the A/C compressor (A/C mass flow sensor) cannot be inspected while it is removed from the vehicle, replace the A/C compressor (A/C mass flow sensor) with a new or a known good one and check that the condition returns to normal.

    2. Check for the DTC.

      Result
      Result Proceed to
      DTC B1479/79 is not output A
      DTC B1479/79 is output B

    B

    CHECK HARNESS AND CONNECTOR (A/C COMPRESSOR (A/C MASS FLOW SENSOR) - A/C AMPLIFIER) Click here

    A

    END

  4. CHECK HARNESS AND CONNECTOR (A/C COMPRESSOR (A/C MASS FLOW SENSOR) - A/C AMPLIFIER)


    1. A019L63E40

      Disconnect the A/C amplifier connector.

    2. A019L5YE03
      Text in Illustration
      *1

      Front view of wire harness connector

      (to A/C Amplifier)
      *2

      Front view of wire harness connector

      (to A/C Compressor (A/C Mass Flow Sensor))

      Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      F50-7 (FLOQ) - D10-3 (QUFL) Always Below 1 Ω
      F50-13 (SG-2) - D10-2 (SGFL) Always Below 1 Ω
      F50-30 (S5-1) - D10-1 (S5FL) Always Below 1 Ω
      F50-7 (FLOQ) - Body ground Always 10 kΩ or higher
      F50-13 (SG-2) - Body ground Always 10 kΩ or higher
      F50-30 (S5-1) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE A/C AMPLIFIER Click here