Last Modified: 4-30-2014 6.6 C Doc ID: RM000000W8D00HX
Model Year: 2006 Model: LX470 Prod Date Range: [05/2005 -           ]
Title: A750F AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM: P2757; Torque Converter Clutch Pressure Control Solenoid Performance (Shift Solenoid Valve SLU); 2006 MY LX470 [05/2005 -        ]

DTC

P2757

Torque Converter Clutch Pressure Control Solenoid Performance (Shift Solenoid Valve SLU)

SYSTEM DESCRIPTION

The ECM uses the signals from the throttle position sensor, air-flow meter, turbine (input) speed sensor, output speed sensor and crankshaft position sensor to monitor the engagement condition of the lock-up clutch.

Then the ECM compares the engagement condition of the lock-up clutch with the lock-up schedule in the ECM memory to detect mechanical problems of the shift solenoid valve SLU, valve body and torque converter clutch.

DTC No.

DTC Detection Condition

Trouble Area

P2757

Lock-up does not occur when driving in lock-up range (normal driving at 80 km/h (50 mph)), or lock-up remains ON in the lock-up OFF range

(2 trip detection logic)
  • Shift solenoid valve SLU remains open or closed
  • Valve body is blocked
  • Torque converter clutch
  • Automatic transmission (clutch, brake or gear, etc.)
  • Line pressure is too low

MONITOR DESCRIPTION

Torque converter lock-up is controlled by the ECM based on the turbine (input) speed sensor NT, output speed sensor SP2, engine rpm, engine load, engine temperature, vehicle speed, transmission temperature, and gear selection. The ECM determines the lock-up status of the torque converter by comparing the engine rpm (NE) to the input turbine rpm (NT). The ECM calculates the actual transmission gear by comparing input turbine rpm (NT) to output shaft rpm (SP2). When conditions are appropriate, the ECM requests lock-up by applying control voltage to the shift solenoid SLU. When the SLU is turned ON, it applies pressure to the lock-up relay valve and locks the torque converter clutch.

If the ECM detects no lock-up after lock-up has been requested or if it detects lock-up when it is not requested, the ECM interprets this as a fault in the shift solenoid valve SLU or lock-up system performance.

The ECM will illuminate the MIL and store the DTC.

Example:

When one of the following conditions is met, the system determines that there is a malfunction.

  • There is a difference in rotation between the input side (engine speed) and output side (input turbine speed) of the torque converter when the ECM commands lock-up ON.

    Engine speed is at least 70 rpm greater than input turbine speed.

  • There is no difference in rotation between the input side (engine speed) and output side (input turbine speed) of the torque converter when the ECM commands lock-up OFF.

    The difference between engine speed and input turbine speed is less than 35 rpm.

MONITOR STRATEGY

Related DTCs

P2757:

Shift solenoid valve SLU/OFF malfunction

Shift solenoid valve SLU/ON malfunction

Required sensors/Components

Shift solenoid valve SLU, Valve body, Vehicle speed sensor, Speed sensor (NT), Speed sensor (NO), Throttle position sensor

Frequency of operation

Continuous

Duration

OFF malfunction

2 sec.

ON malfunction

1.8 sec.

MIL operation

2 driving cycles

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

The monitor will run whenever this DTC is not present.

None

Turbine speed sensor (NT) circuit

Not circuit malfunction

Output speed sensor (NO) circuit

Not circuit malfunction

Shift solenoid valve S1 circuit

Not circuit malfunction

Shift solenoid valve S2 circuit

Not circuit malfunction

Shift solenoid valve SR circuit

Not circuit malfunction

Torque converter clutch pressure control solenoid circuit

Not circuit malfunction

KCS sensor circuit

Not circuit malfunction

ETCS (Electric Throttle control system)

Not system down

Transmission shift position

"D"

ECT (Engine coolant temperature)

40°C (104°F) or more

Spark advance from Max. retard timing by KCS control

0°crankshaft angle or more

Engine

Starting

ECM selected gear

4th or 5th

Vehicle speed

25 km/h (15.5 mph) or more

Shift solenoid valve S1 circuit

Not circuit malfunction

Shift solenoid valve S2 circuit

Not circuit malfunction

Shift solenoid valve SL2 circuit

Not circuit malfunction

1 - 2 shift valve

Not circuit malfunction

Transfer neutral position switch

OFF

Transfer range

"HIGH" *

Transfer range "HIGH" * (This condition is applied only 4WD)

* Following conditions met

Vehicle speed sensor "A" circuit

Not circuit malfunction

Output shaft speed sensor circuit

Not circuit malfunction

Transfer output speed

143 rpm or more

NO/NOtf (Transfer input speed/Transfer output speed)

0.9 to 1.1

OFF malfunction

ECM lock-up command

ON

(SLU pressure: 513 kPa (5.2 kgf*cm 2 , 74 psi) or more)

Vehicle speed

Less than 100 km/h (62.2 mph)

Calculated load value

23.25% or more (A/C OFF)

31.00% or more (A/C ON)

ON malfunction

ECM lock-up command

OFF

(SLU pressure: less than 4 kPa (0.04 kgf*cm 2 , 0.6 psi) or more)

Throttle valve opening angle

9% or more

Vehicle speed

Less than 60 km/h (37.3 mph)

Calculated load value

23.25% or more (A/C OFF)

31.00% or more (A/C ON)

TYPICAL MALFUNCTION THRESHOLDS

OFF malfunction

Engine speed - Turbine speed (NE - NT)

70 rpm or more

ON malfunction

2 detections are necessary per driving cycle: 1st detection; temporary flag ON 2nd detection; pending fault code ON Vehicle speed must be under 10 km/h (6.2 mph) once before 2nd detection.

Engine speed - Turbine speed (NE - NT)

Less than 35 rpm

INSPECTION PROCEDURE

HINT:

Performing the intelligent tester's ACTIVE TEST allows relay, VSV, actuator and other items to be operated without removing any parts. Performing the ACTIVE TEST early in troubleshooting is one way to save time.

The DATA LIST can be displayed during the ACTIVE TEST.

  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 / ACTIVE TEST.
  7. Follow the instructions on the tester and read the ACTIVE TEST.

    Item

    Test Details

    Diagnostic Note

    LOCK UP

    [Test Details]

    Control the shift solenoid SLU to set automatic transmission to lock-up condition

    [Vehicle Condition]

    • Throttle valve opening angle: Less than 35%
    • Vehicle speed: 58 km/h (36 mph) or more

    Possible to check the shift solenoid valve SLU operation

    HINT:

    This test can be conducted in the 5th gear.

  8. Lightly depress the accelerator pedal and check that the engine speed does not change abruptly.

    HINT:

    • When changing the accelerator pedal opening angle while driving, if the engine speed does not change, the lock-up is ON.
    • Slowly release the accelerator pedal in order to decelerate. Suddenly releasing the pedal will close the throttle valve and lock-up may be turned off automatically.

PROCEDURE

1.

CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P2757)

(a) Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.

(b) Turn the ignition switch ON and push the intelligent tester main switch ON.

(c) Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

(d) Read the DTCs using the intelligent tester.

Display (DTC output)

Proceed to

Only P2757 is output

A

P2757 and other DTCs

B

HINT:

If any other codes besides P2757 are output, perform troubleshooting for those DTCs first.

B

GO TO DTC CHART

A

2.

INSPECT SHIFT SOLENOID VALVE SLU

(a) Remove the shift solenoid valve SLU.

(b) Measure the resistance of the solenoid valve.

Standard resistance:

5.0 to 5.6 Ωat 20°C (68°F)

(c) Connect the battery's positive (+) lead to the terminal of the solenoid connector, and the negative (-) lead to the solenoid body.

OK:

Solenoid makes operating noise.
NG

REPLACE SHIFT SOLENOID VALVE SLU

OK

3.

INSPECT TRANSMISSION VALVE BODY ASSEMBLY

OK:

There are no foreign objects on each valve.

NG

REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY

OK

4.

INSPECT TORQUE CONVERTER CLUTCH ASSEMBLY

OK:

The torque converter clutch operates normally.

NG

REPLACE TORQUE CONVERTER CLUTCH ASSEMBLY

OK

REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY