P2757

A750E AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM: P2757: Torque Converter Clutch Pressure Control Solenoid Performance (Shift Solenoid Valve SLU)
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.





MONITOR DESCRIPTION

Torque converter lock-up is controlled by the ECM based on turbine (input) speed sensor NT, output speed sensor SP2, the engine rpm, engine load, engine coolant temperature, vehicle speed, transmission fluid temperature, and gear selection. The ECM determines the lock-up status of the torque converter by comparing the engine rpm (NE) with the input turbine rpm (NT). The ECM calculates the actual transmission gear by comparing the input turbine rpm (NT) with the output shaft rpm (SP2). When the conditions are appropriate, the ECM requests "lock-up" by applying the control voltage to the shift solenoid SLU. When the SLU is turned on, solenoid SLU 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 turns on the MIL and stores the DTC.

Example:

When either of the following is met, the ECM interprets it as a malfunction.

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

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

2. There is no difference in rotation between the input side (engine speed) and output side (input turbine speed) of the torque converter even when the ECM requests lock-up off.

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

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

All





OFF malfunction (A)





OFF malfunction (B)





ON malfunction





TYPICAL MALFUNCTION THRESHOLDS

Both of the following conditions are met: OFF malfunction (A) and (B)

OFF malfunction (A)





OFF malfunction (B)





[ON malfunction]

2 detections are necessary in 1 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 the 2nd detection.

ON malfunction





INSPECTION PROCEDURE

NOTICE:
Perform the universal trip to clear permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

HINT
Performing the Active Test using a Techstream allows components, such as the relay, VSV, and actuator, to be operated without removing any parts. Performing the Active Test as a first step of troubleshooting is one method of shortening labor time.

It is possible to display the Data List during the Active Test.

(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.






HINT
This test can be conducted when the vehicle speed is 36 mph (60 km/h) or more.

(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, but not fully, the accelerator pedal in order to decelerate. (Fully releasing the pedal causes closure of the throttle valve and lock-up may be turned off automatically.)






PROCEDURE

1. CHECK ANY OTHER DTCS 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





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

B -- GO TO DTC CHART Automatic Transmission System - A750E
A -- Continue to next step.

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:





Text in Illustration





(c) Connect the positive (+) lead with a 21 W bulb to terminal 2 and the negative (-) lead to terminal 1 of the solenoid valve connector, then check the movement of the valve.

OK:

The solenoid makes operating sounds.

NG -- REPLACE SHIFT SOLENOID VALVE SLU Disassembly
OK -- Continue to next step.

3. INSPECT TRANSMISSION VALVE BODY ASSEMBLY P0746

NG -- REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY Removal
OK -- Continue to next step.

4. INSPECT TORQUE CONVERTER CLUTCH ASSEMBLY P2714

NG -- REPLACE TORQUE CONVERTER CLUTCH ASSEMBLY Removal

OK -- REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY