AIR CONDITIONING SYSTEM, Diagnostic DTC:B1479/79

DTC Code DTC Name
B1479/79 Flow Sensor Circuit

DESCRIPTION

The flow sensor, which is mounted on the compressor, is used to detect the amount of refrigerant flow. The flow sensor converts the amount of refrigerant flow that is detected to a voltage value to send it to the air conditioning amplifier assembly. The voltage value sent from the 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 air conditioning amplifier assembly supplies 5 V to the flow sensor and monitors changes in the voltage value sent from the flow sensor. The air conditioning amplifier assembly 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 flow sensor circuit

  • Cooler compressor assembly

  • Harness or connector

  • Air conditioning amplifier assembly

WIRING DIAGRAM

A01FFKVE01

INSPECTION PROCEDURE

Note


  • This DTC is stored when there is no refrigerant in the system, when DTC B1423, B14B8 and B1479 are output simultaneously, perform troubleshooting for DTC B14B8 first.

  • When the battery is disconnected or the air conditioning amplifier assembly is replaced, be sure to perform servo motor initialization Click here.

  • Before disconnecting the cable form the negative (-) battery terminal or replacing the air conditioning amplifier assembly, record the last operation state of the air conditioning for each transmitter. After replacement, it is necessary to perform memory registration for each transmitter Click here.

PROCEDURE


  1. READ VALUE USING GTS (FLOW SENSOR)


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

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

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

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

      Flow sensor /

      Min.: 0 V, Max.: 5 V

      		 Value changes between 0.3 V to 4.7 V in accordance with flow sensor condition

      • Check this item with the engine idling, Blower switch LO level and A/C switch on.

      • The flow sensor is malfunctioning when a constant value below 0.3 V or higher than 4.7 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 0.3 and 4.7 V is displayed continuously for more than 4 seconds) C

    B

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    C

    CHECK COOLER COMPRESSOR ASSEMBLY Click here

    A

  2. READ VALUE USING GTS (A/C CUTOFF SIGNAL)


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

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

    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

      Air conditioning control cutoff signal /

      OFF or ON

      OFF: Air conditioning control permitted

      ON: Air conditioning control not permitted

      		 -
      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. CHECK COOLER COMPRESSOR ASSEMBLY


    1. Replace the cooler compressor assembly.


      Tech Tips

      Since the cooler compressor assembly cannot be inspected while it is removed from the vehicle, replace the cooler compressor assembly with pulley with a new or a known good one and check that the condition returns to normal.

    2. Check for DTCs Click here.

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

    B

    CHECK HARNESS AND CONNECTOR (COOLER COMPRESSOR ASSEMBLY - AIR CONDITIONING AMPLIFIER ASSEMBLY) Click here

    A

    END (COOLER COMPRESSOR ASSEMBLY WAS DEFECTIVE)

  4. CHECK HARNESS AND CONNECTOR (COOLER COMPRESSOR ASSEMBLY - AIR CONDITIONING AMPLIFIER ASSEMBLY)


    1. Disconnect the F19 cooler compressor assembly connector.

    2. Disconnect the N81 air conditioning amplifier assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F19-3 (QUFL) - N81-15 (FLOQ) Always Below 1 Ω
      F19-2 (SGFL) - N81-32 (SG-2) Always Below 1 Ω
      F19-1 (S5FL) - N81-13 (S5-3) Always Below 1 Ω
      F19-3 (QUFL) - Body ground Always 10 kΩ or higher
      F19-2 (SGFL) - Body ground Always 10 kΩ or higher
      F19-1 (S5FL) - Body ground Always 10 kΩ or higher
      F19-3 (QUFL) - F19-2 (SGFL) Always 10 kΩ or higher
      F19-1 (S5FL) - F19-2 (SGFL) Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here