P2757

U341E AUTOMATIC TRANSAXLE: AUTOMATIC TRANSAXLE 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, turbine (input) speed sensor, vehicle 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 shift solenoid valve SLU, valve body and torque converter.





MONITOR DESCRIPTION

Torque converter lock-up is controlled by the ECM based on the speed sensor (NT), engine rpm (NE), 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) to the input turbine rpm (NT). The ECM calculates the actual transmission gear by comparing input turbine rpm (NT) to output shaft speed. When conditions are appropriate, the ECM requests lock-up by applying the control voltage to shift solenoid valve 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 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 system judges it as a malfunction.

- There is a difference in the rotations of 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 100 rpm greater than input turbine speed.)

- There is no difference in the rotations of 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





TYPICAL ENABLING CONDITIONS

The following conditions are common to OFF malfunction and ON malfunction.





OFF malfunction:





ON malfunction:





TYPICAL MALFUNCTION THRESHOLDS

OFF malfunction:





[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:





INSPECTION PROCEDURE

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

1. ACTIVE TEST

HINT
Performing the Active Test using the Techstream allows components, such as the relay, VSV, and actuator, to be operated without removing any parts. Performing the Active Test as the 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 60 km/h (36 mph) or less.
- This test can be conducted in 4th 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, but not fully, release the accelerator pedal in order to decelerate. (Fully releasing the pedal will close the throttle valve and lock-up may be turned off.)

PROCEDURE

1. CHECK 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) Select the following items: Powertrain / Engine and ECT / Trouble Codes.

(e) Read the DTCs using the Techstream.

Result





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

B -- GO TO DTC CHART Automatic Transaxle System - U341E
A -- Continue to next step.

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:





(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.

Text in Illustration





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

3. INSPECT TRANSMISSION VALVE BODY ASSEMBLY

OK:

There are no foreign objects on any valves and they operate smoothly.

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

4. INSPECT TORQUE CONVERTER ASSEMBLY

OK:

The torque converter operates normally.

NG -- REPLACE TORQUE CONVERTER ASSEMBLY Removal

OK -- REPAIR OR REPLACE AUTOMATIC TRANSAXLE ASSEMBLY Removal