P2742

A340E AUTOMATIC TRANSMISSION SYSTEM: P2740: Transmission Fluid Temperature Sensor "B" Circuit

DTC P2740 - Transmission Fluid Temperature Sensor "B" Circuit

DTC P2742 - Transmission Fluid Temperature Sensor "B" Circuit Low Input

DTC P2743 - Transmission Fluid Temperature Sensor "B" Circuit High Input

DESCRIPTION





The ATF (Automatic Transmission Fluid) temperature sensor converts the fluid temperature into a resistance value which is input into the ECM.
The ECM applies a voltage to the temperature sensor through ECM terminal THO1.
The sensor resistance changes with the transmission fluid temperature. As the temperature becomes higher, the sensor resistance decreases.
One terminal of the sensor is grounded so that the sensor resistance and the voltage decrease as the temperature becomes higher.
The ECM calculates the fluid temperature based on the voltage signal.





MONITOR DESCRIPTION

The Automatic Transmission Fluid (ATF) temperature sensor converts the ATF temperature to an electrical resistance value. Based on the resistance, the ECM determines the ATF temperature, and detects any open or short malfunctions in the ATF temperature circuit. If the output voltage of the ATF temperature is less than 0.142 V*1 or more than 4.915 V*2, the ECM interprets this as a fault in the ATF temperature sensor or its wiring. The ECM turns on the MIL and stores a DTC.
*1: 150°C (302°F) or more is indicated regardless of the actual ATF temperature.
*2: -40°C (-40°F) is indicated regardless of the actual ATF temperature.

HINT: The ATF temperature can be checked on the Techstream display.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

All





P2740, P2742: Range check (Fluttering, Low voltage)





P2743: Range check (High voltage)





TYPICAL MALFUNCTION THRESHOLDS

P2740: Range check (Fluttering)





P2742: Range check (Low voltage)





P2743: Range check (High voltage)





WIRING DIAGRAM





INSPECTION PROCEDURE

1. DATA LIST

HINT: According to the Data List displayed by Techstream, you can read the values of switches, sensors, actuators and so on without removing parts. Reading the Data List as the first step of troubleshooting is one method to save 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.

(a) Warm up the engine.
(b) Turn the ignition switch OFF.
(c) Connect Techstream to the DLC3.
(d) Turn the ignition switch ON, and turn the tester main switch ON.
(e) Enter the following menus: Powertrain / Engine and ECT / Data List.
(f) According to the display on the tester, read the "Data List".

Engine and ECT





HINT: When DTC P2742 is output and Techstream reading is 150°C (302°F) or more, there is a short circuit.

When DTC P2743 is output and Techstream reading is -40°C (-40°F), there is an open circuit.

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





PROCEDURE

1. INSPECT TRANSMISSION WIRE (ATF TEMPERATURE SENSOR)





(a) Disconnect the transmission wire connector from the transmission.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:





HINT: If the resistance is outside the specified range at either of the ATF temperatures shown in the table below, the driveability of the vehicle may decrease.





NG -- REPAIR OR REPLACE TRANSMISSION WIRE
OK -- Continue to next step.
2. CHECK HARNESS AND CONNECTOR (TRANSMISSION WIRE - ECM)





(a) Connect the transmission wire connector to the transmission.
(b) Disconnect the ECM connectors.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM