Toyota 4Runner manuals

Toyota 4Runner: Torque Converter Clutch Pressure Control Solenoid Performance (Shift Solenoid Valve SLU) (P2757)

Toyota 4Runner Service Manual / Drivetrain / A750e Automatic Transmission / Transaxle / Automatic Transmission System / Torque Converter Clutch Pressure Control Solenoid Performance (Shift Solenoid Valve SLU) (P2757)

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.

DTC Code

DTC Detection Condition

Trouble Area

P2757

Lock-up does not occur when driving in the 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 assembly
  • Automatic transmission (clutch, brake, 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 speed, 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 speed (NE) to the input turbine speed (NT). The ECM calculates the actual transmission gear by comparing input turbine speed (NT) to output shaft speed (SP2). When conditions are appropriate, the ECM requests "lock-up" by applying control voltage to shift solenoid SLU. When SLU is turned on, it applies pressure to the lock-up relay valve and locks the torque converter.

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 turn on the MIL and store the DTC.

Example:

When either of the following is met, the system judges it as a malfunction.

  • There is a difference in speed between the input side (engine speed) and output side (input turbine speed) of the torque converter when the ECM commands lock-up (Engine speed is at least 70 rpm more than input turbine speed.)
  • There is no difference in speed 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/Functional check

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 (A)

2 sec.

OFF malfunction (B)

0.4 sec.

ON malfunction

1.8 sec.

MIL operation

2 driving cycles

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

All

The monitor will run whenever the following DTCs are not stored

P0717 (Turbine speed sensor circuit)

P0722 (Output speed sensor circuit)

P0751, P0973, P0974 (Shift solenoid valve S1 circuit)

P0756, P0976, P0977 (Shift solenoid valve S2 circuit)

P0985, P0986 (Shift solenoid valve SR circuit)

P2759 (Shift solenoid valve SLU circuit)

P0327, P0328, P0332, P0333 (KCS sensor circuit)

P0776 (Shift solenoid valve SL2 circuit)

P0781 (1-2 shift valve)

ETCS (Electric Throttle Control System)

Not system down

Transmission position

"D"

Duration time from shifting "N" to "D"

4 sec. or more

ECT

40°C (104°F) or higher

Spark advance from max. retard timing by KCS control

0° crankshaft angle or more

Engine

Starting

ECM selected gear

2nd, 3rd, 4th or 5th

Vehicle speed

25 km/h (15.5 mph) or more

OFF Malfunction (A)

ECM lock-up command

ON (SLU pressure: 513 kPa (5.2 kgf/cm2, 74 psi) or higher)

Duration time from lock-up on command

3 sec. or more

Turbine speed/Output speed (NT/NO)

0.65 or more, and 0.79 or less

Calculated load value

25.2% or more at 1000 rpm

(Conditions vary with turbine speed)

Vehicle speed

Less than 120 km/h (74.6 mph)

OFF Malfunction (B)

ECM selected gear

2nd

Duration time from shift command of ECM

2 sec. or more

Vehicle speed

2 km/h (1.2 mph) or more

Output speed

2nd → 1st down shift point or more

Throttle valve opening angle

6.5% or more at 2000 rpm

(Conditions varies with engine speed)

Calculated load value

7.75% or more

Following conditions is met: (a), (b), (c), (d) or (e)

-

(a) Turbine speed/Output speed (NT/NO)

3.30 or more, and 7.50 or less

(This means actual gear is 1st)

(b) Turbine speed/Output speed (NT/NO)

1.91 or more, and 2.35 or less

(This means actual gear is 2nd)

(c) Turbine speed/Output speed (NT/NO)

1.28 or more, and 1.53 or less

(This means actual gear is 3rd)

(d) Turbine speed/Output speed (NT/NO)

0.93 or more, and 1.07 or less

(This means actual gear is 4th)

(e) Turbine speed/Output speed (NT/NO)

0.65 or more, and 0.79 or less

(This means actual gear is 5th)

ON Malfunction

ECM lock-up command

OFF (SLU pressure: below 4 kPa (0.04 kgf/cm2, 0.6 psi))

Duration time from lock-up off command

3 sec. or more

Following conditions is met: (a), (b), (c) or (d)

-

(a) Turbine speed/Output speed (NT/NO)

1.91 or more, and 2.35 or less

(This means actual gear is 2nd)

(b) Turbine speed/Output speed (NT/NO)

1.28 or more, and 1.53 or less

(This means actual gear is 3rd)

(c) Turbine speed/Output speed (NT/NO)

0.93 or more, and 1.07 or less

(This means actual gear is 4th)

(d) Turbine speed/Output speed (NT/NO)

0.65 or more, and 0.79 or less

(This means actual gear is 5th)

Throttle valve opening angle

7% or more

Calculated load value

25.2% or more at 1000 rpm

(Conditions vary with turbine speed)

Vehicle speed

Less than 120 km/h (74.6 mph)

TYPICAL MALFUNCTION THRESHOLDS

[OFF malfunction]
  • Both of the following conditions are met: OFF malfunction (A) and (B)
OFF Malfunction (A)

Engine speed - Turbine speed (NE - NT)

70 rpm or more

OFF Malfunction (B)

Turbine speed/Output speed (NT/NO)

Less than 3.30, or more than 7.50

[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.
ON Malfunction

Engine speed - Turbine speed (NE - NT)

Less than 35 rpm

CAUTION / NOTICE / HINT

NOTICE:

Perform the universal trip to clear permanent DTCs (See page ).


1. ACTIVE TEST

HINT:

Using the Techstream to perform Active Tests allows relays, VSVs, actuators and other items to be operated without removing any parts. This non-intrusive functional inspection can be very useful because intermittent operation may be discovered before parts or wiring is disturbed. Performing Active Tests early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Tests.

(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 / Engine and ECT / Active Test.

(g) According to the display on the Techstream, perform the Active Test.

Engine and ECT

Tester Display

Test Part

Control Range

Diagnostic Note

Activate the Lock Up

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

ON or OFF

Possible to check shift solenoid valve SLU operation.

[Vehicle Condition]

  • Throttle valve opening angle: Less than 35%.
  • Vehicle speed: 80 km/h (50 mph) or more.

HINT:

  • This test can be conducted when the vehicle speed is 80 km/h (50 mph) or more.
  • This test can be conducted in 5th gear.

(h) 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, lock-up is on.
  • Slowly release the accelerator pedal in order to decelerate, but do not fully release the pedal. (Fully releasing the pedal will close the throttle valve and lock-up may be turned off automatically.)

PROCEDURE

1.

CHECK DTC OUTPUT (IN ADDITION TO DTC P2757)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(e) Read the DTCs using the Techstream.

Result

Result

Proceed to

Only P2757 is output

A

P2757 and other DTCs are output

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 shift solenoid valve SLU.


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

Standard Resistance:

Tester Connection

Condition

Specified Condition

1 - 2

20°C (68°F)

5.0 to 5.6 Ω

(c) Apply 12 V battery voltage to the shift solenoid valve and check that the valve moves and makes an operating noise.

OK:

Measurement Condition

Specified Condition

  • Battery positive (+) with a 21 W bulb → Terminal 2
  • Battery negative (-) → Terminal 1

Valve moves and makes operating noise

Text in Illustration

*a

Component without harness connected

(Shift Solenoid Valve SLU)


NG

REPLACE SHIFT SOLENOID VALVE SLU

OK

3.

INSPECT TRANSMISSION VALVE BODY ASSEMBLY



NG

REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY

OK

4.

INSPECT TORQUE CONVERTER ASSEMBLY



OK

REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY


NG

REPLACE TORQUE CONVERTER ASSEMBLY

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