ECD SYSTEM, Diagnostic DTC:24(1)

DTC Code DTC Name
24(1) Intake Air Temperature Sensor Circuit Malfunction

DESCRIPTION

The intake air temperature sensor is built into the intake manifold and senses the intake air temperature. A thermistor built in the sensor changes the resistance value according to the intake air temperature. The lower the intake air temperature, the greater the thermistor resistance value, and the higher the intake air temperature, the lower the thermistor resistance value (See Fig. 1).

A01KGZSE01

The intake air temperature sensor is connected to the ECM. The 5 V power source voltage in the ECM is applied to the intake air temperature sensor from terminal THIA via a resistor R. That is the resistor R and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes. Based on this signal, the ECM increases the fuel injection volume to improve drivability during cold engine operation.

DTC No. DTC Detecting Condition Trouble Area
24(1) Open or short in intake air temp. sensor circuit for 0.5 sec. or more

  • Open or short in water temp. sensor circuit

  • intake air temp sensor

  • ECM

Tech Tips

After confirming DTC No. 22, use the intelligent tester to confirm the intake air temperature from the CURRENT DATA.

Temperature displayed Malfunction
-40°C (-40°F) Open circuit
140°C (284°F) or more Short circuit

WIRING DIAGRAM

A01KFPXE02

INSPECTION PROCEDURE

Tech Tips


  • If DTC Nos. 22, 24, 35 and 39, E2 (sensor ground) may be open.

  • Read freeze frame data using intelligent tester. Because freeze frame records the engine conditions when the malfunction is detected. When troubleshooting it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.

  • When not using the intelligent tester go to step 6.

PROCEDURE


  1. READ VALUE OF INTELLIGENT TESTER (INTAKE TEMP.)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch ON and push the intelligent tester main switch ON.

    3. Read the temperature value on the intelligent tester.

      Temp.
      Same as actual water temperature.
      Result
      A B OK
      -40°C (-40°F) 140°C (248°F) or more Same as actual water temperature

      Tech Tips


      • If there is open circuit, intelligent tester indicates -40°C (-40°F) (A).

      • If there is short circuit, intelligent tester indicates 140°C (284°F) or more (B).


    B

    CHECK ECM Click here

    OK

    CHECK FOR INTERMITTENT PROBLEMS Click here

    A

  2. CHECK WIRE HARNESS (CHECK FOR OPEN)


    1. A01KHY1E01
      Text in Illustration
      *1 Intake Air Temp. Sensor

      Disconnect the intake air temperature sensor connector.

    2. Connect the sensor wire harness terminals together.

    3. Turn the ignition switch ON.

    4. Read the temperature value on the intelligent tester.

      Temperature value
      140°C (284°F) or more

    5. Confirm good connection at sensor.


    OK

    REPLACE E.F.I. INTAKE AIR TEMPERATURE SENSOR

    NG

  3. CHECK ECM (CHECK FOR OPEN)


    1. A01KELVE03

      Connect between terminals THIA and E2 of the ECM (E8) connector.

      Tech Tips

      The intake air temperature sensor connector is disconnected. Before checking, do a visual and contact pressure check for the ECM connector Click here.

    2. Read the temperature value on the intelligent tester.

      Temperature value
      140°C (284°F) or more

    3. Confirm good connection at sensor.


    OK

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    NG

    REPLACE ECM

  4. CHECK ECM


    1. Disconnect the intake air temperature sensor connector.

    2. Turn the ignition switch ON.

    3. Read the temperature value on the intelligent tester.

      Temperature value
      -40°C (-40°F)

    OK

    REPLACE E.F.I. INTAKE AIR TEMPERATURE SENSOR

    NG

  5. CHECK ECM


    1. A01KGV0E01
      Text in Illustration
      *1 E8 Connector

      Disconnect the ECM (E8) connector.

      Tech Tips

      The intake air temperature sensor connector is disconnected.

    2. Read the temperature value on the intelligent tester.

      Temperature value
      -40°C (-40°F)

    OK

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    NG

    CHECK AND REPLACE ECM Click here

  6. CHECK ECM (CHECK VOLTAGE)


    1. A01KELVE04

      Turn the ignition switch ON.

    2. Check the voltage between terminals of the ECM connector as shown in the table and illustration.

      Voltage

      intake air Temp.

      °C (°F)

      Terminal

      (Positive terminal ←→ Negative terminal)

      		 Voltage

      20 (68)

      (Engine is cool)

      		 THIA (E8-22) ←→ E2 (E8-20) 0.2 - 3.8V

      80 (176)

      (Engine is hot)

      		 THIA (E8-22) ←→ E2 (E8-20) 0.1 - 1.5 V

    OK

    CHECK FOR INTERMITTENT PROBLEMS Click here

    NG

  7. INSPECT E.F.I. INTAKE AIR TEMPERATURE SENSOR


    1. A01KEKF

      Disconnect the intake air temp. sensor connector.

    2. Remove the intake air temp. sensor.

    3. Measure resistance between terminals.

      Resistance
      Within acceptable zone on the chart below

      intake air temp.

      °C (°F)

      		 Resistance
      20 (68) 2 - 3 kΩ
      80 (176) 0.2 - 0.4 kΩ

    NG

    REPLACE E.F.I. INTAKE AIR TEMPERATURE SENSOR

    OK

  8. CHECK WIRE HARNESS (ECM - INTAKE AIR TEMPERATURE SENSOR)


    1. A01KIKXE01

      Disconnect the intake air temp. sensor connector.

    2. Disconnect the ECM (E8) connector.

    3. Check the continuity between terminals of intake air temp. sensor and ECM connectors as shown in the illustration and table.

      Continuity (Check for open)

      Terminal

      (intake air temp. sensor ←→ ECM)

      		 Standard
      2 ←→ THIA (E8-22) Continuity
      1 ←→ E2 (E8-20)
      Continuity (Check for short)

      Terminal

      (ECM ←→ ECM(Ground))

      		 Standard
      THIA (E8-22) ←→ E1 (E7-22) No continuity

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

    CHECK AND REPLACE ECM Click here