P2740

A750F 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 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, 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 turns on the MIL and stores a DTC.

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)

COMPONENT OPERATING RANGE

WIRING DIAGRAM

INSPECTION PROCEDURE

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.

1. Warm up the engine.
2. Turn the ignition switch OFF.
3. Connect Techstream to the DLC3.
4. Turn the ignition switch ON, and turn the tester main switch ON.
5. Enter the following menus: Powertrain / Engine and ECT / Data List.
6. According to the display on 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 (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:

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:

(d) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for short):

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