P2743

A750E 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 No. 2 Automatic Transmission Fluid (ATF) temperature sensor is on the transmission, just before the oil cooler inlet pipeline.

If the ECM detects an abnormally high ATF temperature through this sensor, it illuminates the warning light to indicate the problem to the driver.

HINT
* The ATF temperature is liable to increase under vehicle conditions such as towing, climbing hills and in traffic.
* If there is a short malfunction in the No. 2 ATF temperature sensor, the ECM receives signals from the sensor, which indicate that the ATF temperature is 150°C (302°F) or more.

The symptoms and recovery conditions, when the sensor is normal or there is a short malfunction in the sensor, are as shown in the table below.





HINT
*1: When the ATF temperature is normal, the transmission locks up in 5th gear with the shift lever in the D position and in 4th gear with the shift lever in the 4th position.

*2: When the ATF temperature is in the normal range, it decreases to less than 135°C (275°F) within 5 minutes of the shift lever being moved to the P or N position, while idling.





MONITOR DESCRIPTION

These DTCs indicate an open or short in the No. 2 Automatic Transmission Fluid (ATF) temperature sensor circuit. The No. 2 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 No. 2 ATF temperature sensor circuit. If the resistance (voltage) of the No. 2 ATF temperature sensor is less than 25 Ohms (0.046 V) or more than 156 kOhms (4.915 V), the ECM interprets this as a fault in the No. 2 ATF temperature sensor or its wiring. The ECM blinks the ATF warning light and stores a DTC.

WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
Perform the universal trip to clear permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

HINT
According to the Data List displayed on a Techstream, you can read the values of components, such as the switches, sensors, actuators, without removing any parts. Reading the Data List as a first step of troubleshooting is one method of shortening labor time.

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

1. Warm up the engine.

2. Turn the ignition switch off.

3. Connect the Techstream to the DLC3.

4. Turn the ignition switch to ON.

5. Turn the Techstream on.

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

7. 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.

Measure the resistance between terminal THO2 and the body ground.





PROCEDURE

1. INSPECT TRANSMISSION WIRE (NO. 2 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:





Text in Illustration





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:





Text in Illustration





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM Removal