Last Modified: 4-30-2014 6.6 C Doc ID: RM0000012XR004X
Model Year: 2006 Model: LX470 Prod Date Range: [05/2005 -           ]
Title: A750F AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM: P2740,P2742,P2743; Transmission Fluid Temperature Sensor "B" Circuit; 2006 MY LX470 [05/2005 -        ]

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 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:

  • ATF temperature rises quickly when towing, climbing hills, in traffic, etc.
  • If the No. 2 ATF temperature sensor becomes short-circuited, the signal that indicates that the ATF temperature is 150°C (302°F) or higher is input in 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 (275°F)
  • ATF temperature warning light remains ON
  • ATF temperature less than 135°C (275°F)*2
  • 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
    1. ATF temperature more than 130°C (266°F)
    1. Engine coolant temperature more than 95°C (203°F)
  • Lock-up at 3rd gear*1
  • ATF temperature less than 110°C (230°F)*2 and engine coolant temperature more than 95°C (203°F)

Sensor is short-circuited
  • Any conditions
  • ATF temperature 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*1
  • Symptoms still occur

HINT:

*1: When ATF temperature is normal, transmission lock-up occurs in 5th gear with the shift lever on D, and 4th gear with the shift lever on 4.

*2: When ATF temperature is in the normal range, it decreases to less than 135°C (275°F) within 5 minutes with the shift lever on P or N in an idling state.

DTC No.

DTC Detection Condition

Trouble Area

P2740
  • (a) and (b) are detected momentarily within 0.5 sec. when neither P2742 or P2743 are detected (1 trip detection logic):
    1. No. 2 ATF temperature sensor resistance is less than 79 Ω
    2. No. 2 ATF temperature sensor resistance is more than 156 kΩ

HINT:

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

P2742

No. 2 ATF temperature sensor resistance is less than 79 Ω for 0.5 sec. or more (1 trip detection logic)
  • Short in No. 2 ATF temperature sensor circuit
  • No. 2 ATF temperature sensor
  • ECM

P2743

No. 2 ATF temperature sensor resistance is more than 156 kΩ when 15 minutes or more have passed after the engine start

DTC is detected for 0.5 sec. or more (1 trip detection logic)
  • Open in No. 2 ATF temperature sensor circuit
  • No. 2 ATF temperature sensor
  • ECM

MONITOR DESCRIPTION

ATF temperature sensor converts ATF temperature to 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 intelligent tester display.

MONITOR STRATEGY

Related DTCs

P2740: ATF temperature sensor/Range check (Chattering)

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 sec.

MIL operation

Immediate

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

The monitor will run whenever the following DTCs are not present

None

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

The typical enabling condition is not available.

-

P2743: Range check (High voltage)

Time after engine start

15 min. 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

Atmospheric temperature to approx. 130°C (266°F)

WIRING DIAGRAM

Refer to DTC P0710 2006 MY LX470 [05/2005 -        ]; A750F AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM: P0710,P0712,P0713; Transmission Fluid Temperature Sensor "A" Circuit+ .

INSPECTION PROCEDURE

HINT:

Using the intelligent tester's DATA LIST allows switch, sensor, actuator and other item values to be read without removing any parts. Reading the DATA LIST early in troubleshooting is one way 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.

  1. Warm up the engine.
  2. Turn the ignition switch OFF.
  3. Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.
  4. Turn the ignition switch ON.
  5. Turn the intelligent tester ON.
  6. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST.
  7. Follow the instructions on the tester and read the DATA LIST.

Item

Measurement Item/

Range (Display)

Normal Condition

Diagnostic Note

AT FLUID TEMP

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 during cold soak

If value is -40°C (-40°F) or 215°C (419°F), ATF temperature sensor circuit is opened or short circuited

HINT:

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

    Measure the resistance between terminal THO2 (OT2) 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 (ATF TEMPERATURE SENSOR)

(a) Disconnect the E1 ATF temperature sensor connector.

(b) Measure the resistance of the temperature sensor.

Standard resistance:

Tester Connection

Specified Condition

1 (OT2-) - 9 (OT2+)

79 Ω to 156 kΩ

1 (OT2-) - Body ground

10 kΩ or higher

9 (OT2+) - Body ground

10 kΩ or higher
NG

REPAIR OR REPLACE TRANSMISSION WIRE

OK

2.

CHECK WIRE HARNESS (TRANSMISSION WIRE - ECM)

(a) Disconnect the E7 and E8 ECM connectors.

(b) Measure the resistance of the wire harness side connectors.

Standard resistance:

Tester Connection

Specified Condition

E7-32 (THO2) - E8-28 (E2)

25 Ω to 156 kΩ

E7-32 (THO2) - Body ground

10 kΩ or higher

E8-28 (E2) - Body ground

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK

REPLACE ECM