P2757
DTC P2757 Torque Converter Clutch Pressure Control Solenoid Performance (Shift Solenoid Valve SLU)DESCRIPTION
The ECM uses the signals from the throttle position sensor, mass 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 any mechanical problems with the shift solenoid valve SLU, valve body or 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, 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 input turbine rpm (NT) with 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 any of the following are met, the ECM interprets it as a malfunction.
1. There is a difference in rotation between before and after 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 before and after 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
Part 1:
Part 2:
TYPICAL MALFUNCTION THRESHOLDS
INSPECTION PROCEDURE
HINT: Performing the ACTIVE TEST using the intelligent tester 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.
1. Warm up the engine.
2. Turn the ignition switch off.
3. Connect the intelligent tester together with the CAN VIM (controller area network vehicle interface module) to the DLC3.
4. Turn the ignition switch to the ON position.
5. Push the "ON" button of the tester.
6. Clear the DTC.
7. Select the items "DIAGNOSIS/ENHANCED OBD II/ACTIVE TEST/LOCK UP".
8. According to the display on the tester, perform the "ACTIVE TEST". Scan Tool Testing and Procedures
HINT: This test can be conducted when the vehicle speed is 36 mph (60 km/h) or more.
9. 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.)
