AUTOMATIC TRANSMISSION SYSTEM (for 1GR-FE), Diagnostic DTC:P2742, P2743

DTC Code DTC Name
P2742 Transmission Fluid Temperature Sensor "B" Circuit Low Input
P2743 Transmission Fluid Temperature Sensor "B" Circuit High Input

DESCRIPTION

The Automatic Transmission Fluid (ATF) temperature sensor is on the transmission, just in front of the oil cooler inlet pipeline.

If the ECM detects an abnormally high ATF temperature near this sensor, it illuminates the warning light.

Tech Tips


  • The temperature of the ATF easily rises when towing, climbing hills, in traffic, etc.

  • If the ATF temperature sensor becomes short-circuited, the signal that indicates that the ATF temperature is 150°C (302°F) or higher is input into the ECM.

Vehicle conditions when the sensor is normal and when the sensor is short-circuited are indicated in the table below.

No. 2 ATF Temperature Sensor State Detection Condition Symptom Recovery Condition
Sensor is normal ATF temperature higher than 150°C (302°F) ATF temperature warning light remains ON ATF temperature below 135°C (275°F)*1
ATF temperature higher than 130°C (266°F) Shift point too high ATF temperature below 110°C (230°F)

Conditions (a) and (b) are met:

(a) ATF temperature higher than 130°C (266°F)

(b) Engine coolant temperature higher than 95°C (203°F)

 Lock-up in 3rd gear*2 ATF temperature below 110°C (230°F)*1 and engine coolant temperature higher than 95°C (203°F)
Sensor is short-circuited Any conditions

  • ATF temperature warning light blinks

  • Shift point too high

 Symptoms still occur
Engine coolant temperature higher than 95°C (203°F) Lock-up in 3rd gear*2 Symptoms still occur

Tech Tips

*1: When ATF temperature is in the normal range, it decreases to below 135°C (275°F) within 5 minutes with the shift lever in P or N in an idling state.

*2: When ATF temperature is normal, transmission lock-up occurs in 5th gear with the shift lever in D or with the S5 range selected, and in 4th gear with the S4 range selected.

DTC Code DTC Detection Condition Trouble Area
P2742 No. 2 ATF temperature sensor resistance is below 25 Ω (0.046 V) for 0.5 sec. or more (1-trip detection logic).

  • Short in No. 2 ATF temperature sensor circuit

  • No. 2 ATF temperature sensor (transmission wire)

  • ECM
P2743

ATF temperature sensor resistance is higher than 156 kΩ (4.915 V) for 0.5 sec. or more and either condition is met (1-trip detection logic):

(A) 15 min. or more have elapsed after the engine start when the engine coolant temperature or intake air temperature is -29.375°C (-20.875°F) or less.

(B) 10 sec. or more have elapsed after the engine start when the engine coolant temperature and intake air temperature are higher than -29.375°C (-20.875°F).

  • Open in No. 2 ATF temperature sensor circuit

  • No. 2 ATF temperature sensor (transmission wire)

  • ECM

MONITOR DESCRIPTION

The ATF temperature sensor converts the ATF temperature into an electrical resistance value. Based on the resistance, the ECM determines the ATF temperature, and the ECM detects an open or short in the ATF temperature circuit. If the resistance value of the ATF temperature sensor is below 25 Ω*1 or higher than 156 kΩ*2, the ECM interprets this as a fault in the ATF sensor or wiring. The ATF temperature warning light blinks and the ECM stores the DTC.

Tech Tips


  • *1: 150°C (302°F) or higher is indicated regardless of the actual ATF temperature.

  • *2: -40°C (-40°F) is indicated regardless of the actual ATF temperature.

  • The ATF temperature can be checked on the intelligent tester display.

WIRING DIAGRAM

Refer to DTC P0712 Click here.

INSPECTION PROCEDURE


  1. DATA LIST

    Tech Tips

    Using the intelligent tester to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. This non-intrusive inspection can be very useful because intermittent conditions or signals may be discovered before parts or wiring is disturbed. Reading the Data List information early in troubleshooting is one way to save diagnostic time.

    Note

    In the table below, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not.


    1. Warm up the engine.

    2. Turn the ignition switch off.

    3. Connect the intelligent tester to the DLC3.

    4. Turn the ignition switch to ON.

    5. Turn the intelligent tester on.

    6. Enter the following menus: Powertrain / Engine and ECT / Data List.

    7. According to the display on the tester, read the Data List.

      Engine and ECT
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      A/T Oil Temperature 2

      No. 2 ATF temperature sensor value/

      Min.: -40°C (-40°F)

      Max.: 215°C (419°F)

      • After stall test: Approximately 80°C (176°F)

      • With engine cold: Equal to ambient temperature

      		 If the value is -40°C (-40°F) or 215°C (419°F), the No. 2 ATF temperature sensor circuit is open or shorted.

      Tech Tips


      • When DTC P2742 is output and the intelligent tester output is 150°C (302°F) or higher, there is a short circuit.

      • When DTC P2743 is output and the intelligent tester output is -40°C (-40°F), there is an open circuit.

        Check the temperature displayed on the intelligent tester in order to check if a malfunction exists.

      Temperature Displayed Malfunction
      -40°C (-40°F) Open circuit
      150°C (302°F) or higher Short circuit

PROCEDURE


  1. INSPECT TRANSMISSION WIRE (NO. 2 ATF TEMPERATURE SENSOR)


    1. A01DP6IE08
      Text in Illustration
      *a

      Component without harness connected

      (Transmission Wire)

      Disconnect the C30 transmission wire connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      1 (OT2-) - 9 (OT2+) Always 25 Ω to 156 kΩ
      1 (OT2-) - Body ground Always 10 kΩ or higher
      9 (OT2+) - Body ground Always 10 kΩ or higher

      Tech Tips

      If the resistance is out of the specified range at one of the ATF temperatures shown in the table below, the driveability of the vehicle may decrease.

      Resistance (Reference)
      ATF Temperature Specified Condition
      10°C (50°F) 5 to 8 kΩ
      25°C (77°F) 2.5 to 4.5 kΩ
      110°C (230°F) 0.22 to 0.28 kΩ

    NG

    REPAIR OR REPLACE NO. 2 ATF TEMPERATURE SENSOR (TRANSMISSION WIRE) Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (TRANSMISSION WIRE - ECM)


    1. A01DSHDE06
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to ECM)

      Disconnect the C35 and C36 ECM connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      C36-11 (THO2) - C35-8 (ETHW) Always 25 Ω to 156 kΩ
      C36-11 (THO2) - Body ground Always 10 kΩ or higher
      C35-8 (ETHW) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM Click here