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.

(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.

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.

(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.

GO TO DTC CHART

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

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)

REPLACE SHIFT SOLENOID VALVE SLU

3.	INSPECT TRANSMISSION VALVE BODY ASSEMBLY

REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY

4.	INSPECT TORQUE CONVERTER ASSEMBLY

REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY

REPLACE TORQUE CONVERTER ASSEMBLY

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