ECD SYSTEM, Diagnostic DTC:24(2)

DTC Code DTC Name
24(2) Atmospheric Temperature Sensor Circuit Malfunction

DESCRIPTION

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

A01KGZSE01

The atmospheric temperature sensor is connected to the ECM. The 5 V power source voltage in the ECM is applied to the atmospheric temperature sensor from terminal THAF via a resistor R. That is resistor R and the atmospheric temperature sensor are connected in series. When the resistance value of the atmospheric 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(2) Open or short in atmospheric temp. sensor circuit for 0.5 sec. or more

  • Open or short in water temp. sensor circuit

  • Atmospheric temp. sensor (built into air flow meter)

  • ECM

Tech Tips

After confirming DTC 24, use the intelligent tester to confirm the atmospheric temperature from the CURRENT DATA.

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

WIRING DIAGRAM

(a) Refer to DTC No. 31 on page Click here

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 (ATMOSPHERIC 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 atmospheric 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 WIRE HARNESS (CHECK FOR SHORT) Click here

    OK

    CHECK FOR INTERMITTENT PROBLEMS Click here

    A

  2. CHECK WIRE HARNESS (CHECK FOR OPEN)


    1. A01KFK0E01

      Disconnect the air flow meter connector.

    2. Connect the air flow meter wire harness terminals THA and E2.

    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 air flow meter.


    OK

    REPLACE INTAKE MASS AIR FLOW METER ASSEMBLY

    NG

  3. CHECK ECM (CHECK FOR OPEN)


    1. A01KELVE05

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

      Tech Tips

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

    2. Turn the ignition switch ON.

    3. Read the temperature value on the intelligent tester.

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

    OK

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    NG

    REPLACE ECM

  4. CHECK WIRE HARNESS (CHECK FOR SHORT)


    1. Disconnect the air flow meter connector.

    2. Turn the ignition switch ON.

    3. Read the temperature value on the intelligent tester.

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

    OK

    REPLACE INTAKE MASS AIR FLOW METER ASSEMBLY

    NG

  5. CHECK ECM (CHECK FOR SHORT)


    1. A01KGV0E01
      Text in Illustration
      *1 E8 Connector

      Disconnect the ECM (E8) connector.

      Tech Tips

      The air flow meter connector is disconnected.

    2. Turn the ignition switch ON.

    3. 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. A01KELVE06

      Turn the ignition switch ON.

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

      Voltage

      atmospheric Temp.

      °C (°F)

      Terminal

      (Positive terminal ←→ Negative terminal)

      		 Voltage

      20 (68)

      (Engine is cool)

      		 THAF (E8-13) ←→ E2 (E8-20) 0.2 - 3.8 V

      80 (176)

      (Engine is hot)

      		 THAF (E8-13) ←→ E2 (E8-20) 0.1 - 1.5 V

    OK

    CHECK FOR INTERMITTENT PROBLEMS Click here

    NG

  7. CHECK INTAKE MASS AIR FLOW METER ASSEMBLY


    1. A01KG37E01
      Text in Illustration
      *1 Ohmmeter

      Remove the air flow meter.

    2. Using an ohmmeter, measure the resistance between terminals THAF and E2.

      Terminals Resistance Temperature
      THAF (4) ←→ E2 (5) 12.5 - 16.9 kΩ -20°C (-4°F)
      THAF (4) ←→ E2 (5) 2.19 - 2.67 kΩ 20°C (68°F)
      THAF (4) ←→ E2 (5) 0.50 - 0.68 kΩ 60°C (140°F)
    3. A01KGLSE01
      Text in Illustration
      *1 Voltmeter
      *a Air

      Inspect for operation.


      1. Connect the air flow meter connector.

      2. Connect the negative (-) terminal cable to the battery.

      3. Turn the ignition switch ON.

      4. Using a voltmeter, connect the positive (+) tester probe to terminal VG, and negative (-) tester probe to terminal EVG.

      5. Blow air into the air flow meter, and check that the voltage fluctuates.


    NG

    REPLACE INTAKE MASS AIR FLOW METER ASSEMBLY

    OK

  8. CHECK WIRE HARNESS (ECM - AIR FLOW METER)


    1. A01KGUJE01

      Disconnect the air flow meter connector.

    2. Disconnect the ECM (E8) connector.

    3. Check the continuity between terminals of the air flow meter and ECM connectors as shown in the illustration and table.

      Continuity (Check for open)

      Terminal

      (Air flow meter ←→ ECM)

      		 Standard
      THAF (4) ←→ THAF (E8-13) Continuity
      E2 (5) ←→ E2 (E8-20)
      Continuity (Check for short)

      Terminal

      (ECM ←→ ECM(Ground))

      		 Standard
      THAF (E8-13) ←→ E1 (E7-22) No continuity

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

    CHECK AND REPLACE ECM Click here