Last Modified: 11-29-2007 1.6 C
Service Category: Drivetrain Section: Automatic Transmission/Transaxle
Model Year: 2008 Model: Sequoia Doc ID: RM0000012XR023X
Title: A750E AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DESCRIPTION (2008 Sequoia)

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 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.

HINT:

  • The temperature of 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 more than 150°C (302°F)

"A/T OIL TEMP" warning light remains ON

ATF temperature less than 135°C (275°F)*1

ATF temperature more than 130°C (266°F)

Shift point too high

ATF temperature less than 110°C (230°F)

When the conditions (a) and (b) are satisfied.

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

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

Lock-up at 3rd gear*2

ATF temperature less than 110°C (230°F)*1 and engine coolant temperature more than 95°C (203°F)

Sensor is short-circuited

Any conditions
  • "A/T OIL TEMP" warning light remains ON
  • Shift point too high

Symptoms still occur

Engine coolant temperature more than 95°C (203°F)

Lock-up at 3rd gear*2

Symptoms still occur

HINT:

*1: When ATF temperature is in the normal range, it decreases to less than 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, and 4th gear with the S4 range selected.

DTC No.

DTC Detection Condition

Trouble Area

P2740

(a) and (b) are detected momentarily within 0.5 seconds when neither P2742 nor P2743 are detected. (1-trip detection logic)

(a) No. 2 ATF temperature sensor resistance is less than 25 Ω (0.046 V).

(b) No. 2 ATF temperature sensor resistance is more than 156 kΩ (4.915 V).

HINT:

Within 0.5 seconds, the malfunction switches from (a) to (b) or from (b) to (a).
  • Open or short in No. 2 ATF temperature sensor circuit
  • Transmission wire (No. 2 ATF temperature sensor)
  • ECM

P2742

No. 2 ATF temperature sensor resistance is less than 25 Ω (0.046 V) for 0.5 seconds or more. (1-trip detection logic)
  • Short in No. 2 ATF temperature sensor circuit
  • Transmission wire (No. 2 ATF temperature sensor)
  • ECM

P2743

When 15 minutes or more have elapsed after engine is started, No. 2 ATF temperature sensor resistance is more than 156 kΩ (4.915 V) for 0.5 seconds or more (1-trip detection logic)
  • Open in No. 2 ATF temperature sensor circuit
  • Transmission wire (No. 2 ATF temperature sensor)
  • ECM

MONITOR DESCRIPTION

The ATF temperature sensor converts 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 is less than 25 Ω*1 or more than 156 kΩ*2, the ECM interprets this as a fault in the ATF sensor or wiring. The ECM will illuminate the MIL and store the DTC.

HINT:

  • *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.
  • The ATF temperature can be checked on the Techstream display.

MONITOR STRATEGY

Related DTCs

P2740: ATF temperature sensor/Range check (Fluttering)

P2742: ATF temperature sensor/Range check (Low resistance)

P2743: ATF temperature sensor/Range check (High resistance)

Required sensors/Components

ATF temperature sensor

Frequency of operation

Continuous

Duration

0.5 seconds

MIL operation

Immediately

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

All

The monitor will run whenever the following DTCs are not present

None

P2740: Range Check (Chattering)

The typical enabling condition is not available.

-

P2742: Range Check (Low Voltage)

The typical enabling condition is not available.

-

P2743: Range Check (High Voltage)

Time after engine start

15 minutes or more

TYPICAL MALFUNCTION THRESHOLDS

P2740: Range Check (Chattering)

ATF temperature sensor voltage

Less than 0.046 V or more than 4.915 V

P2742: Range Check (Low Voltage)

ATF temperature sensor voltage

Less than 0.046 V

P2743: Range Check (High Voltage)

ATF temperature sensor voltage

More than 4.915 V

COMPONENT OPERATING RANGE

ATF temperature sensor voltage

0.046 V to 4.915 V

WIRING DIAGRAM

Refer to DTC P0710 A750E AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DESCRIPTION (2008 Sequoia)+ .

INSPECTION PROCEDURE

1. DATA LIST

HINT:

Using the Techstream 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.

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 the Techstream to the DLC3.

(d) Turn the ignition switch to ON.

(e) Turn the Techstream on.

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

(g) According to the display on the Techstream, read the Data List.

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)
  • Equal to ambient temperature while engine is cold

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

HINT:

  • When DTC P2742 is output and the Techstream output is 150°C (302°F) or more, there is a short circuit.
  • When DTC P2743 is output and the Techstream output is -40°C (-40°F), there is an open circuit.

    Measure the resistance between terminal THO2 and the body ground.

Temperature Displayed

Malfunction

-40°C (-40°F)

Open circuit

150°C (302°F) or more

Short circuit

PROCEDURE

1.

INSPECT TRANSMISSION WIRE (NO. 2 ATF TEMPERATURE SENSOR)

(a) Disconnect the D41 transmission wire connector.

(b) 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

HINT:

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

Standard Resistance:

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
OK

2.

CHECK HARNESS AND CONNECTOR (TRANSMISSION WIRE - ECM)

(a) Disconnect the D56 ECM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

D56-99 (THO2) - D56-98 (ETHA)

Always

25 Ω to 156 kΩ

D56-99 (THO2) - Body ground

Always

10 kΩ or higher

D56-98 (ETHA) - Body ground

Always

10 kΩ or higher
OK