AB60E AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DESCRIPTION (2008 Sequoia)

Last Modified: 11-29-2007		1.6 C
Service Category: Drivetrain	Section: Automatic Transmission/Transaxle
Model Year: 2008	Model: Sequoia	Doc ID: RM000000W8D046X
Title: AB60E AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DESCRIPTION (2008 Sequoia)

DTC

P2757

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

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 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
Shift solenoid valve SLU
Torque converter clutch
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 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
Frequency of operation	Continuous
Duration	OFF malfunction (A) 2 seconds OFF malfunction (B) 0.4 seconds ON malfunction 1.8 seconds
MIL operation	2 driving cycles
Sequence of operation	None

TYPICAL ENABLING CONDITIONS

All

The monitor will run whenever the following DTCs are not present	None
Turbine speed sensor circuit	Not circuit malfunction
Output speed sensor circuit	Not circuit malfunction
Shift solenoid valve S1 circuit	Not circuit malfunction
Shift solenoid valve S2 circuit	Not circuit malfunction
Shift solenoid valve S3 circuit	Not circuit malfunction
Shift solenoid valve S4 circuit	Not circuit malfunction
Shift solenoid valve SR circuit	Not circuit malfunction
Shift solenoid valve SLU circuit	Not circuit malfunction
KCS sensor circuit	Not circuit malfunction
ETCS (Electric Throttle Control System)	Not system down
Transmission position	"D"
Duration time from shifting "N" to "D"	4 seconds or more
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	2nd, 3rd, 4th, 5th or 6th
Vehicle speed	25 km/h (15.5 mph) or more
Shift solenoid valve S1 circuit	Not circuit off malfunction
Shift solenoid valve S3 circuit	Not circuit on malfunction
Shift solenoid valve S4 circuit	Not circuit off malfunction
Shift solenoid valve SL2 circuit	Not circuit on malfunction
1 - 2 shift valve	Not malfunction
Sequence valve	Not malfunction

OFF Malfunction (A)

ECM lock-up command

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

Duration time from lock-up on command

3 seconds or more

Vehicle speed

Less than 120 km/h (74.5 mph)

OFF Malfunction (B)

ECM selected gear	2nd
Vehicle speed	2 km/h (1.3 mph) or more
Output speed	2nd → 1st down-shift point or more
Throttle valve opening angle	9% or more at 2000 rpm (Conditions vary with engine speed)

ON Malfunction

ECM lock-up command	OFF (SLU pressure: Less than 4 kPa (0.04 kgf/ cm², 0.6 psi))
Duration time from lock-up off command	3 seconds or more
Throttle valve opening angle	6% or more
Vehicle speed	Less than 120 km/h (74.5 mph) at 2nd gear (Varies with ECM selected gear)

TYPICAL MALFUNCTION THRESHOLDS

OFF malfunction is detected when OFF malfunction (A) and (B) are set.

OFF Malfunction (A)

Engine speed - Turbine speed (NE - NT)

70 rpm or more

OFF Malfunction (B)

Turbine speed/Output speed (NT/NO)

Less than 3.11 or more than 7.58

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

COMPONENT OPERATING RANGE

Speed sensor (NT)

Input speed is equal to engine speed when lock-up ON.

INSPECTION PROCEDURE

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 condition

ON or OFF

Possible to check shift solenoid valve SLU operation

[Vehicle Condition]

Throttle valve opening angle: Less than 35%
Vehicle speed: 60 km/h (36 mph) or more

HINT:

This test can be conducted when the vehicle speed is 60 km/h (36 mph) or more.
Perform this test while driving in the 5th or 6th 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.

2.	INSPECT SHIFT SOLENOID VALVE SLU

(a) Remove the 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) Connect the battery positive (+) lead with a 21 W bulb to terminal 2 and the negative (-) lead to terminal 1 of the solenoid valve connector. Then check that the valve moves and makes an operating noise.

OK:

Valve moves and makes an operating noise.

3.	INSPECT TRANSMISSION VALVE BODY ASSEMBLY

(a) Check the transmission valve body assembly.

OK:

There are no foreign objects on each valve.

4.	INSPECT TORQUE CONVERTER CLUTCH ASSEMBLY

(a) Check the torque converter clutch assembly .

OK:

The torque converter clutch operates normally.