A340E Automatic Transmission System

A340E AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM: P2742,P2743: Transmission Fluid Temperature Sensor "B" Circuit Low Input
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 resistance of the ATF temperature is less than 79 Ohms or more than 156 kOhms, 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.

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

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

P2742: Range check (Low resistance)





P2743: Range check (High resistance)





Condition (A)





Condition (B)





TYPICAL MALFUNCTION THRESHOLDS

P2742: Range check (Low resistance)





P2743: Range check (High resistance)





COMPONENT OPERATING RANGE





WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
Perform the universal trip to clear permanent DTCs DTC Check / Clear.

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.

NOTICE:
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 to ON.

(e) Turn the Techstream on.

(f) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data.

(g) According to the display on the Techstream, 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 Removal
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 Removal