P2757
A750E AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM: P2757: Torque Converter Clutch Pressure Control Solenoid Performance (Shift Solenoid Valve SLU)
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 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 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 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
All
OFF Malfunction (A)
OFF Malfunction (B)
ON Malfunction
TYPICAL MALFUNCTION THRESHOLDS
[OFF Malfunction]
- Both of the following conditions are met: OFF malfunction (A) and (B)
OFF Malfunction (A)
OFF Malfunction (B)
[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 (6.2mph) once before 2nd detection.
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.
(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.
Engine and ECT
HINT: This test can be conducted when the vehicle speed is 60 km/h (37 mph) 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 the accelerator pedal in order to decelerate, but do not fully release the pedal. (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
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:
(c) Connect the battery's 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:
The solenoid makes an operating sound.
NG -- REPLACE SHIFT SOLENOID VALVE SLU
OK -- Continue to next step.
3. INSPECT TRANSMISSION VALVE BODY ASSEMBLY (see chapter 2 in the Problem Symptoms Table)
(a) Check the transmission valve body assembly Installation.
OK:
There are no foreign objects on any valves and they operate smoothly.
NG -- REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY
OK -- Continue to next step.
4. INSPECT TORQUE CONVERTER CLUTCH ASSEMBLY
(a) Inspect the torque converter clutch assembly Testing and Inspection.
OK:
The torque converter clutch operates normally.
NG -- REPLACE TORQUE CONVERTER CLUTCH ASSEMBLY
OK -- REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY